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Arch Suicide Res. Author manuscript; available in PMC 2023 October 01.
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Published in final edited form as:

Arch Suicide Res. 2022 ; 26(4): 1736–1756. doi:10.1080/13811118.2021.2022551.

Characteristics of Suicidal Ideation: A Systematic Review

Katherine W. Reeves, MS, PMHNP-BC1,2, Genesis Vasconez, MS, PMNP-BC2, Sandra J.
Weiss, PhD, DNSc1,2
1Depression Center, University of California, San Francisco, CA 94312 USA
2Department of Community Health Systems, University of California, San Francisco, CA 94132
USA
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Abstract
Background: The exploration of inter- and intra-individual variability in suicidal ideation (SI)
is vital to suicide research. However, this research relies on the identification and measurement of
standardized SI characteristics.

Objective: This review aimed to identify characteristics of SI examined in research, describe how
these characteristics are measured, and assess how they are aligned with those included in the
Columbia Suicide Severity Rating Scale (C-SSRS).

Methods: Four databases were systematically searched, and relevant data was extracted. The
C-SSRS provided a framework for comparing SI names, measures and operational definitions.

Results: After comparing operational definitions of identified characteristics, five core domains
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emerged: 1) severity, 2) temporality, 3) variability, 4) controllability, and 5) deterrents/reasons for

ideating. Except for variability, all SI characteristics in the literature were congruent with those
measured in the C-SSRS.

Conclusions: This review highlighted conceptual and methodologic inconsistencies in the

study of SI, specifically the nomenclature, measurement and definitions of SI characteristics.
Standardized approaches to the study of SI characteristics are needed. These approaches will
enhance accurate and reliable measurement of SI, allow for findings to be synthesized across
studies and propel the exploration of inter and intra-individual SI variability leading to more
individualized and effective SI treatment.

Keywords
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Suicide; suicidal ideation; SI characteristics; SI subtypes; literature review

Correspondence: Katherine W. Reeves, University of California, San Francisco, 2 Koret Way, San Francisco CA.,
katie.reeves@ucsf.edu.
CONFLICT OF INTEREST
The authors declare that they have no conflict of interest.
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INTRODUCTION
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Suicide is a growing public health concern in the United States (US). It is the 10th leading
cause of death among adults (Centers for Disease Control &Prevention [CDC], n.d.) and
the 2nd leading cause of death among those age 10–30 (Curtin & Heron, 2019). Death by
suicide claimed more than 47,000 American lives in 2017 (CDC, n. d.), and continues to
rise rapidly across all demographics (Hedegaard et al., 2020). Between 1999 and 2018, rates
of suicide in US adults increased 35%, (Hedeegard et al., 2020) and, between 2007 and
2017, more than doubled among young people age 10–24 (Curton & Heron, 2019). Recent
evidence suggests that the failure of suicide prevention efforts may be due to a lack of
understanding surrounding the experience of suicidal ideation (SI), one of suicide’s strongest
predictors (Klonsky et al., 2016).

The National Institute on Mental Health (National Institution on Mental Health [NIMH],
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n.d.) defines SI as “thinking about, considering or planning suicide” (NIMH, n.d.). SI rates
are highest among US high school students, with about 20% reporting having seriously
considering suicide in 2018 (Ivey-Stephenson, 2020). However, the COVID-19 crisis has
greatly impacted the mental health of Americans. Prior to the emergence of COVID-19, SI
occurred in about four percent of American adults at any given time (Czeisler et al., 2020).
In June 2020, these rates more than doubled to about 11% (Czeisler et al., 2020), further
suggesting that the burden of suicide in the US is increasing.

SI research has primarily focused on identifying risk for SI, as well as identifying who,
among those who experience SI, are at risk for suicidal behavior (SB), which includes
suicide attempts and death by suicide. Despite a research emphasis on suicide prevention in
the US, there has been no substantial progress over the last 50 years in the ability to predict
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who is at risk for SB among those with SI (Franklin et al., 2017). Although predicting risk
is vital to preventing suicide, our ability to do so may be limited by what we know about the
experience of SI itself.

SI is phenotypically heterogeneous, varying in its presentation by duration, frequency,

quality and severity within and between individuals (Kleinman et al., 2017; Rizk et al.,
2018; Witte et al., 2005). However, as evidenced by the frequent use of binary SI variables
in research, much of suicide literature has operationalized the concept of SI as homogenous
– either one has considered suicide, or they have not. Although it is important to measure
prevalence rates and trends of the larger phenomenon, this approach may yield results
that overlook vital scientific variability. Measures which use continuous scales, such as the
Beck Scale for Suicidal Ideation (Beck & Steer, 1991), offer more depth than dichotomous
measures, typically consisting of many items and resulting in a composite score. Although
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these scales have demonstrated validity in measuring suicide risk and sometimes include
questions regarding characteristics of the SI experience, they do not typically delineate
specific SI characteristics or offer subscales for such characteristics. For example, one
individual may have continuous and intense suicidal thoughts, but has varying levels of
intent to act on those thoughts. In contrast, another individual may have short bursts of
suicidal thought in which intent spikes, offset by moments of no intent between bouts. The
distinct characteristics within these two experiences are not likely represented in a single

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score yet may have enormous implications for their suicide risk or points of intervention.
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Labeling someone as simply having SI, or even assessing degree of SI on a continuous

scale without further characterization, homogenizes the experience. These approaches limit
consideration of nuance that may potentially be crucial in understanding the mechanisms
responsible in SI development and more accurately identifying who among those with SI is
at greatest risk for suicidal behavior.

In an effort to move beyond homogeneity, some recent studies have alluded to the presence
of SI subtypes (Bernanke et al., 2017; Kleinman et al., 2017; Rizk et al., 2018; Oquendo
et al., 2008). Subtyping has become popular in depression research as groups of people
with similar sets of depressive symptoms often share etiological mechanisms of the disorder
and similar responses to specific treatments. This approach can lead to scientific advances
such as empirically based etiological theory and precisely targeted interventions. Depression
and suicide, although related, have one relevant distinction. Depression is a diagnosis or
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disorder identified in the DSM-V, with a set of subsequent symptoms, whereas SI is not.
Although experts have made the case to include SI as a diagnosis in the DSM (Oquendo
et al., 2008), SI has predominately been classified as one of depression’s symptoms and
has no identified set of unique characteristics. The lack of agreed upon characteristics
makes the process of subtyping more challenging for researchers. Identifying a standardized
set of SI characteristics could shed light on the nature of such SI symptoms and assist
in identifying SI subtypes. Elaboration of SI characteristics would also allow for the
quantitative measurement of nuance in the SI experience on the individual level, leading
to more accurate, precision-based results and improved efficacy of personalized suicide
prevention interventions (Odgers & Jensen, 2020; Rabasco & Sheehan, 2021).

Recently an important body of research has begun to examine SI at the individual level.
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These investigators propose that data collected at the interindividual (group) level are
largely not generalizable to the individual in suicide research. Fisher et al. (2018) argue
that group-based findings are only generalizable to the individual when the distribution of
the phenomenon is from a sufficiently large sampling of random points, and that lack of this
more individualized focus in research will likely result in flawed theory and systematically
biased clinical assessments. Rather than looking for predictors of SI across large groups,
this cadre of emerging researchers acknowledge SI’s heterogeneity, both between and within
individuals, mostly by using intensive longitudinal methodologies (Rabasco & Sheehan,
2021). Intensive longitudinal studies repeat measures frequently (at least daily) in order to
identify within person changes and get an accurate understanding of how suicidal thoughts
evolve over time (Shiffman et al., 2008; Rabasco & Sheehan, 2021). With these methods,
researchers can better describe the experience of SI, as well as address when individuals
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may be more at risk for suicide, informing more precise safety assessments and clinical
interventions.

The purpose of this review was to identify SI characteristics that are measured in this
progressive literature. We synthesized how these characteristics are named, measured and
defined across studies. From our findings we generate recommendations for future SI
research regarding nomenclature, definition, and measurement of SI characteristics. A

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standardized approach in these areas could enhance more accurate and reliable measurement
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as well as lead to a more integrated body of knowledge in the field of SI research.

The Columbia Suicide Severity Rating Scale as an Organizational Framework

The Columbia Suicide Severity Rating Scale (C-SSRS) is a gold standard SI measure and
one of the first assessments to acknowledge distinct SI characteristics. We used the C-SSRS
as a guide to organize the characteristics identified by individual studies in the literature.
The C-SSRS was developed in 2011 in response to a lack of consistent nomenclature in
suicide research and has since been validated in both clinical and research settings amongst
diverse populations (Posner et al., 2011). Along with measuring components of suicidal
behavior, the C-SSRS aims to measure two distinct concepts within SI – severity and
intensity. The measure of intensity includes five distinct characteristics of SI: frequency,
duration, controllability, deterrents, and reason for ideating. These C-SSRS characteristics
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provide a structure for comparing and analyzing nomenclature, measures, and definitions of
SI characteristics reported in the literature.

Aims
1. Identify specific characteristics of suicidal ideation (SI) that have been examined
in research.

2. Describe the ways in which these characteristics of SI have been measured.

3. Assess the degree to which SI characteristics examined in research are aligned

with characteristics of SI included in the Columbia Suicide Severity Rating Scale
(C-SSRS).
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METHODS
This systematic review followed guidelines published by the Preferred Reporting Items for
Systematic Review and Meta-Analyses (Moher et al., 2009). No protocol was registered.

Eligibility Criteria
All studies published on or before June 1st, 2020 that met the following criteria were
included in this review.

Inclusion Criteria:
1. Original research published in peer reviewed journals.

2. Studies that measured specific characteristics of the SI experience in any

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population.

3. Studies which, if using a repeated measures design, examined characteristics of

SI at least once per day in order to access the ongoing nature of the SI trajectory.

Exclusion Criteria:
1. Articles that were not published in English.

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2. Literature reviews, meta-analyses, case studies, qualitative studies or editorials.

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3. Studies that analyzed SI as a binary variable.

4. Studies that conflate, or combine, characteristics of the individual (i.e.

demographics, environmental factors, personality traits, diagnoses, etc.) with
characteristics of SI in their analysis.

As this is the first literature review to analyze SI characteristics and in order to delineate
the full body of literature, no publication dates were specified for inclusion. For the same
reasons, no specific populations (e.g., age groups) were targeted.

Search Strategy
The following databases were searched for relevant articles on June 1st, 2020: Pubmed,
Embase, Web of Science and PsychInfo. The following is an example search string:
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(“suicidal ideation”[MeSH] OR “suicidal ideation”[ti] OR “suicidal ideation”[ot]) AND

(biotype OR subtype OR subgroup OR phenotype OR “variability”). Filters were used to
select only peer reviewed journal articles. Articles obtained from database searches were
supplemented with articles that were listed in selected articles’ reference lists and found
through individual searches.

Study Selection
Article titles and abstracts were initially reviewed for inclusion and exclusion criteria by the
primary reviewer after being uploaded to Covidence, a systematic review software. If studies
appeared to meet inclusion criteria, the full text was obtained and reviewed. If the article,
once again, met inclusion criteria, it was saved, and the reference was added to a list of
eligible studies. A second reviewer assessed a random selection of 100 discarded articles.
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Articles identified as meeting inclusion criteria from this sample of articles were discussed
between both reviewers. The second reviewer also assessed all full text articles for inclusion
or exclusion. Decisions for inclusion or exclusion required unanimous consensus between
both reviewers. All disputes were settled by discussing with a third reviewer until consensus
was obtained. Once all eligible studies were identified, each was reviewed multiple times
and relevant data was extracted.

Data Extraction
Using tables in Microsoft Word, the following data was extracted from the included studies:
study author, year, setting, sample characteristics, data collection methods, name of reported
characteristics of SI, measure of SI characteristic, and definition of SI characteristic (if
reported). If definitions of SI characteristics were not explicitly stated, the definition was
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interpreted by the primary reviewer based on the measure used. Definitions were then
discussed among all three reviewers until consensus was reached. Data was extracted
initially by the primary reviewer. The second reviewer independently extracted the same
data. The two data sets were compared, and all discrepancies were reviewed by both
reviewers until consensus was reached.

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RESULTS
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The initial literature search generated 1,473 articles. Individual searches also yielded nine
articles resulting in a total of 1,482 articles. Five hundred and eighteen duplicates were
removed resulting in 955 unique titles for abstract review. Of those, 48 appeared to meet
inclusion/exclusion criteria and were selected for full text review. After a comprehensive
reading, 10 articles continued to satisfy inclusion/exclusion and were ultimately included in
the review (see Figure 1).

Sample and Design

There were 7 unique studies represented in this review. However, three of the 7 studies
were associated with more than one article, resulting in 10 articles for final inclusion. For
example, Witte et al. (2005) published preliminary results; whereas, Witte et al. (2006)
reported complete results from the same study. Although there was no range of dates
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identified for inclusion a priori, the publication dates of the literature ranged from 2005 to
2019, with 7 of the 10 articles published in or after 2017.

Setting.—Of the 7 studies, three took place in the community (Kleinman et al., 2017, 2018;
Nock, 2009; Witte et al., 2005, 2006), four were conducted on psychiatric in-patient units
(Czyz et al., 2019; Hallensleben et al., 2018, 2019; Kleinman et al., 2017, 2018), one was
an experiment performed in a laboratory (Rizk et al., 2018), and one was conducted in an
active-duty military environment (Nock et al., 2018).

Population.—Three of the seven studies included adolescents or young adults (under 25

years; Czyz et al., 2019; Nock et al., 2009; Witte et al., 2005, 2006), two included adults
(Hallensleben et al., 2018, 2019; Rizk et al., 2018) and two looked at both young adults
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and adults (Kleinman, 2017, 2018; Nock, 2018). Two studies did not restrict inclusion
based on psychiatric history (Nock et al., 2018; Witte et al., 2005, 2006). One study
included participants who had a suicide attempt within the last year (Kleinman, 2017, 2018).
One study included participants with a suicide attempt within the last month and/or SI
within the last week (Czyz et al., 2019). The final study included only participants with
a diagnosis of Major Depressive Disorder (MDD; Rizk et al., 2018). Sample sizes ranged
primarily from 20 to 108 participants, with one outlier looking at 3,916 participants. Six
of the studies consisted of over 60% women (with five studies having more than 70%
women). The majority of the samples included primarily white participants, with four
studies reporting over 70% white participants. Only two studies reported between 45 and
67% white participants while two did not report the race of their participants.
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Design.—Five of the seven studies used longitudinal methods, one used a prospective
design, and one was an experiment performed in a laboratory. As per inclusion criteria,
all five studies that used a longitudinal design used at least once daily measures of SI.
Measurement of SI occurred once daily (Czyz et al., 2019; Witte et al., 2005, 2006),
twice daily (with the addition of unlimited participant-initiated entries; Nock et al., 2009),
four times daily (Kleinman et al., 2017) and ten times daily (Hallensleben et al., 2018,
2019). The duration of data collection ranged from six days to 6 weeks with one study

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duration depending on the length of in-patient stay (Kleinman et al., 2017, 2018). Four
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studies used Ecological Momentary Assessment (EMA) to collect SI data; three of which
were smartphone based and one which used paper questionnaires. Czyz et al. (2019) also
conducted surveys via smartphone.

Identification of SI Characteristics
Results of the review were divided into three sections: 1) the identification of SI
characteristics, 2) measures or operational definitions used to collect data on each SI
characteristic, and 3) the congruence of SI characteristics in the literature with those used in
the C-SSRS based on their names, measurement and definition.

From the 7 studies, 12 characteristics of SI were identified: intensity, duration, frequency,

desire to die, intent to die, ability to resist suicide urge, controllability, level of passive SI,
level of active SI, urge severity and SI variability. Four studies reported duration of SI (Czyz
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et al., 2019; Nock, et al., 2018, 2009; Rizk et al., 2018; Witte et al., 2006, 2005), three
reported frequency of SI (Czyz et al., 2019; Kleinman et al., 2017, 2018; Nock et al., 2009),
and three reported intensity of SI (Kleinman et al., 2017, 2018; Nock et al., 2009; Witte
et al., 2005, 2006). Two studies reported SI variability (Kleniman et al., 2017; Witte et al.,
2005, 2006). Two studies reported on controllability, although one named it “ability to resist
urge” (Kleinman et al., 2017, 2018; Nock et al., 2018). The following characteristics were
only measured in one study: desire to die (Kleniman et al., 2017, 2018), intent (Kleinman
et al., 2017, 2018), level of passive SI (Hallensleben et al., 2018, 2019), level of active SI,
(Hallensleben et al., 2018, 2019), and urge severity (Czyz et al., 2019; See table 2).

SI Measurement
Two of the seven studies in this review used individual items taken from validated SI
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measures. Two studies reported using tools developed from validated SI measures to
measure SI characteristics. One study used an aggregate score of the 36-item Suicide
Probability Scale (SPS) to measure SI intensity and duration (Witte et al., 2005, 2006). One
study used a single item from the Beck Scale for Suicidal Ideation to measure SI duration
(Rizk et al., 2018). Two studies developed items from the C-SSRS (Nock et al., 2018; Czyz
et al., 2019), and one reported developing items based on the Self Injurious Thoughts and
Behaviors Survey (SITBS; Nock et al., 2009). Over half of the SI characteristic measures
used a single item. All but one measure included between 1 and 4 items. The SPS, used by
Witte et al. (2005 & 2006) had 36 items. Table 3 provides details on the names, measures
and operational definitions of SI characteristics across all studies.

Table 4 provides information about the validity and reliability of the measures used. Five
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of the studies adapted their measure(s) of SI characteristics from a larger measure of

SI. Although, in most cases, the original measure from which the item was taken had
established validity and reliability, there was no evidence that the adapted item(s) being
used from the larger measure were assessed for validity or reliability as distinct, stand-alone
measures of the SI characteristic. Two of the studies created new items/measures of the SI
characteristics and provided no information regarding their validity or reliability.

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Congruence of SI Characteristics with the C-SSRS

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SI characteristics identified in this review were compared with the SI characteristics

measured in the C-SSRS, based on the operational definitions associated with each SI
characteristic measure. Table 5 provides a comparison of SI characteristics identified in this
review with characteristics included in the C-SSRS.

Five of the names used to describe the 12 SI characteristic were also used in the C-SSRS
(intensity, severity, frequency, duration and controllability). However, many studies did not
operationally define these characteristics as they are operationally defined in the C-SSRS.
Only two of the seven studies adapted SI measures specifically from the C-SSRS and
none used the same items as those in the C-SSRS. The studies also examined five SI
characteristics not measured by the C-SSRS (variability, “desire to die”, “level of passive
SI”, “level of active SI”, and “urge severity”). One study appears to measure the concept of
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controllability, but instead uses the name “ability to resist urge”.

Severity.—There was a high level of congruence between studies reviewed and the C-
SSRS for inclusion of ‘Severity’ as a SI characteristic. All but one study (Rizk et al.,
2018) measured a characteristic with a similar operational definition to the one used in the
C-SSRS. However, only one of these studies actually used a similar name – “urge severity”
– to identify the characteristic (Czyz et al. 2019). Although their measurement approach
indicated they were measuring ‘severity’, two studies referred to it as “intensity” (Nock
et al., 2009; Witte et al., 2005, 2006), one as the “level” of SI (Hallensleben et al., 2018,
2019), and another as “self-injurious thoughts and behaviors” (Nock et al., 2018). A fourth
study referred to what was ostensibly ‘severity’ of SI using three separate terms: general SI,
“desire to die” and “intent” to die (Kleinman et al., 2017, 2018).
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Frequency and Duration.—Five studies measured frequency, as defined by the C-SSRS.

However, only three used the name “frequency” (Czyz et al., 2019; Kleinman et al., 2017,
2018; Nock et al., 2009) while two labeled measures of frequency as “duration” (Nock et al.,
2018; Witte et al., 2005, 2006). Four studies actually measured duration (Czyz et al., 2019;
Nock et al., 2009, 2018; Rizk et al., 2018), with all four calling the variable “duration”.

Controllability.—Controllability, as defined by the C-SSRS, was measured as a

characteristic of SI in two studies (Kleinman et al., 2017, 2018; Nock et al., 2018). One
study named the characteristic “controllability” (Nock et al., 2018), while one study named
it “ability to resist urge” (Kleinman et al., 2017, 2018).

Deterrents/Reason for Ideating and Variability.—No studies in this review identified

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characteristics of SI similar to “deterrents” or “reason for ideating”, as defined in the

C-SSRS. Two studies identified variability as a characteristic of SI. This was a novel
characteristic that is not measured in the C-SSRS (Kleinman et al., 2018; Witte et al., 2006).

DISCUSSION
The purpose of this review was to identify specific characteristics of SI delineated
in SI research to date, determine how they are operationally defined and measured,

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and assess their alignment with SI characteristics included in the C-SSRS. Twelve SI
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characteristics were identified in the literature. However, after comparing measures and
operational definitions of all 12 SI characteristics, they were essentially measuring five core
domains: severity, temporality (frequency and duration), controllability, deterrents/reasons
for ideating, and variability. For many of the characteristics, their names, measures and
operational definitions were conflated in the literature, representing a significant conceptual
problem in SI research. Four of the five characteristics were congruent with characteristics
included in the C-SSRS. No standardized measures of the SI characteristics were used
across studies.

SI Characteristics
Twelve characteristics were initially identified across the studies. However, after reviewing
the nature of their measurement and related operational definitions, it became apparent that
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5 characteristic domains were actually being measured: severity, temporality (frequency

and duration), controllability, deterrents/reasons for ideating, and variability. There was
inconsistency and lack of clarity in terms used to describe specific characteristics across
studies, and in some cases, apparent mislabeling of certain characteristics. These problems
were augmented by a lack of standardized measures for assessing the same characteristics
across studies. Such conceptual and methodologic discrepancies could inhibit scientific
progress if not addressed. Exemplars of conceptual inconsistency are highlighted below for
severity and temporality – the most commonly reported characteristics.

Severity.—The term “severity” suggests gravity or seriousness and possesses a worrisome

quality. In comparison, “intensity” indicates strength or power without being adverse in
nature. The C-SSRS uses the 2 terms to describe different components of SI. It operationally
defines the term “severity” by assessing for the presence of suicidal thoughts, a plan for
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suicide, or intention to act on that plan. It then uses the term “intensity” as the title for
the section of questions measuring the remaining 5 characteristics (frequency, duration,
controllability, deterrents and reasons for ideating). However, across the studies reviewed
these two terms were operationally defined as if they were the same variable.

Temporality.—Frequency and duration are well defined concepts in any thesaurus.

Frequency refers to the number of times an event occurs, while duration is the length of
time over which the event occurs. However, the two appear to be conflated at times in in the
current SI literature. The confusion seems to lie in their application to suicidal thoughts and
how to measure the temporality of a thought. Evidence suggests that people have episodes
of SI that last between seconds and hours (Nock et al., 2009; Rizk et al., 2017). Chronicity
appears to lie in the high frequency of SI episodes rather than true sustained thoughts
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of suicide (Nock et al., 2009; Rizk et al., 2017). If it is assumed that SI is experienced
in episodes, then the concept’s duration and frequency can be applied more easily. The
duration of SI would be the length of an SI episode, whereas frequency would refer to the
number of episodes.

Variability.—Variability refers to the change in SI over a designated period of time.

Variability of SI is not assessed in the C-SSRS but was identified as an SI characteristic

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in two studies. This review suggests its importance to the field of SI research. Witte et
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al. (2006) found that SI variability was predictive of a multiple suicide attempt history.
Kleiman et al. (2017) found that SI variability helped differentiate five SI subtypes and that
low variability of SI predicted a recent history of a suicide attempt. Although noteworthy
as a SI characteristic, the nature of variability is complicated by the unit of time between
measurements and the feature of SI that is measured. When variability is studied, it is
imperative to determine what is fluctuating (e.g. severity, controllability) and for how long.
For example, one researcher may choose to measure daily changes in SI severity while
another chooses to measure hourly changes of SI controllability. Both would report findings
of SI variability. Future research looking at SI variability should be aware of this potential
pitfall and clearly state the time period and quality of variability being examined.

Controllability and deterrents/reasons for ideating—Controllability and deterrents/

reasons for ideating were the least measured characteristics of SI. It is not clear why these
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characteristics have received little attention in SI research. Both are characteristics included
in the C-SSRS and, therefore, are considered by experts to have potential importance to the
field (Posner et al., 2011). Future research is needed to develop appropriate measures and
enhanced understanding of these SI characteristics.

Standardization in Measurement
Although individual studies in this review generally provided appropriate rationale for
the use of SI measures, no standardized measures were used to assess individual SI
characteristics. Appropriate and valid measures are generally developed secondary to
agreement about concept names and definitions. The lack of consistency in names and
definitions of SI characteristics is likely the reason for a lack of standardized measures.
There is an urgent need for universal nomenclature to describe SI characteristics, along
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with clear conceptual definitions and subsequent development of psychometrically sound,

standardized measures. Without these, it will not be possible to effectively integrate results
across studies and develop a cohesive body of knowledge regarding SI.

Congruence of SI Characteristics in the Literature with Those in the C-SSRS

The SI characteristics studied to date measure all but one of the characteristics found
in the C-SSRS. This overlap has significant potential to advance the field, in light of
the C-SSRS’s standing as a valid clinical measure of suicidal ideation and behavior. As
this body of literature grows, synthesis of study results will be imperative in order to
impact meaningful clinical change. Future integration of the literature should use names,
definitions and measures of SI characteristics consistent with the C-SSRS. The C-SSRS is
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already well-established in clinical settings as a screening tool. If future research identifies

a specific SI characteristic from the C-SSRS that has particular relevance for a SI subtype
or population, then clinical settings can readily use the C-SSRS (or other SI measure)
to screen for that characteristic. In addition, interventions can be developed that address
specific characteristics such as controllability or frequency of SI rather than depending on
more general, imprecise interventions that may not be as useful to individuals in managing
their unique struggles with SI.

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The field should also be open to research that can improve clinical and research efficacy
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of the C-SSRS. Building on discoveries from SI research, studies to refine the interview’s
assessment of various SI characteristics may be warranted. Based on findings from this
review, potential measurement of new characteristics such as variability should also be
considered for the C-SSRS. Lastly, further psychometric testing for each characteristic
subscale is warranted, including validity and reliability testing across varied populations and
contexts to assure cultural and sociodemographic integrity of SI assessment.

Limitations
Although this study followed guidelines for systematic reviews proposed by PRISMA,
limitations still exist. Because characteristics of SI do not have consistent nomenclature,
the search for relevant articles was difficult. Although we started with about one thousand
articles, it is possible that different search terms would have rendered articles that were
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missed. Similarly, the targeted body of literature appears to be small. However, because this
review intentionally delineated an emerging literature, a small number of relevant articles
was expected.

In addition, the lack of well-defined characteristics required inference at times regarding the
definitions of reported SI characteristics. Although this was done as objectively as possible,
some degree of subjective interpretation was necessary.

CONCLUSIONS
This review highlighted inconsistencies in the emerging field of SI research, specifically
in the nomenclature, definition, and measurement of SI characteristics. Although some
conceptual disparity is common in new areas of research, clearer consensus regarding the
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conceptualization and measurement of SI characteristics is needed to advance the field.

Although the quantification of SI on a granular and individual level is a new approach

to suicide prevention, the promise of this research is substantial. The identification of
phenotypic SI subtypes may lead to better etiological understanding of SI. Subsequently,
by breaking down those who experience SI into groups based on distinct etiologies,
more targeted interventions can be derived. Similarly, intensive longitudinal methods are
beginning to explain the dynamics of suicidal thought. These methods can generate insights
regarding moment to moment environmental mechanisms that may be responsible for
changes in suicidal thought (e.g., time of day, interpersonal difficulties). Findings could
be directly implemented into effective suicide prevention interventions by targeting person
and group specific triggers of SI.
Author Manuscript

This research is timely, as SI and suicide rates skyrocket. In order to meet the challenge,
researchers must build essential scaffolding for this emerging field by standardizing
approaches to SI measurement. Standardization will allow for findings to be synthesized
across studies, enhance more accurate and reliable measurement of SI, and lead to a more
integrated and useful body of knowledge.

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 Reeves et al. Page 12

ACKNOWLEDGEMENTS
Author Manuscript

Funding:
This work was supported by the National Institutes of Health [T32NR016920].

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Figure 1.
PRISMA Flowchart
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Table 1.

C-SSRS SI Characteristics Defined

C-SSRS SI Item Wording Item Response Options Definition

Characteristic
Reeves et al.

Name

Severity Have you wished you were dead or wished you could go to Yes/No “The strength of feeling during which
sleep and not wake up? one contemplates acting on suicidal
thoughts.”
Have you actually had any thoughts of killing yourself? Yes/No

Have you been thinking about how you might do this? Yes/No

Have you had these thoughts and had some intention of Yes/No
acting on them?
Have you started to work out or worked out the details of Yes/No
how to kill yourself? Do you intend to carry out this plan?
Frequency How many times have you had these thoughts? (1) Less than once a week “How often one experiences suicidal
(2) Once a week thoughts.”
(3) 2–5 times in week
(4) Daily or almost daily
(5) Many times each day

Duration When you have the thoughts how long do they last? (1) Fleeting - few seconds or minutes “The length of time one has a
(2) Less than 1 hour/some of the time continuous suicidal thought.”
(3) 1–4 hours/a lot of time
(4) 4–8 hours/most of day
(5) More than 8 hours/persistent or continuous

Controllability Could/can you stop thinking about killing yourself or (1) Easily able to control thoughts “The ease with which one could stop
wanting to die if you want to? (2) Can control thoughts with little difficulty (3) Can control thoughts themselves from considering suicide.”
with some difficulty
(4) Can control thoughts with a lot of difficulty
(5) Unable to control thoughts
(0) Does not attempt to control thoughts

Deterrents Are there things - anyone or anything (e.g., family, (1) Deterrents definitely stopped you from attempting suicide “The presence of a person or thing
religion, pain of death) - that stopped you from wanting (2) Deterrents probably stopped you that stops one from wanting to die or

Arch Suicide Res. Author manuscript; available in PMC 2023 October 01.
to die or acting on thoughts of committing suicide? (3) Uncertain that deterrents stopped you commit suicide.”
(4) Deterrents most likely did not stop you
(5) Deterrents definitely did not stop you
(0) Does not apply

Reasons for What sort of reasons did you have for thinking about (1) Completely to get attention, revenge or a reaction from others “The reason for thoughts of suicide.”
Ideating wanting to die or killing yourself? Was it to end the pain or (2) Mostly to get attention, revenge or a reaction from others
stop the way you were feeling (in other words you couldn’t (3) Equally to get attention, revenge or a reaction from others
go on living with this pain or how you were feeling) or was and to end/stop the pain
it to get attention, revenge or a reaction from others? Or (4) Mostly to end or stop the pain (you couldn’t go on living with the
both? pain or how you were feeling)
(5) Completely to end or stop the pain (you couldn’t go on living with
the pain or how you were feeling)
(0) Does not apply
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Table 2:

Study Sample and Design

Author (Year) Setting Sample Characteristics Data Collection Methods

Reeves et al.

Age (mean age in Inclusion Criteria – Sample Female White Design Method Frequency Duration
years) Psychiatric History size (%) (%) (per day)
Witte (2005) Community College Students None 108 60 NR Longitudinal Questionnaire 1 6 weeks
(19.3)

Witte (2006) Community College Students None 108 60 NR Longitudinal Questionnaire 1 6 weeks
(19.3)

Nock (2009) Community Adolescent/ Recent history of 30 87 87 Longitudinal Smart phone EMA 2+ 2 weeks
Young adult (17.3) NSSI

Kleiman (2017) Community Young adult Suicide attempt in last 54 79 73 Longitudinal Smart phone EMA 4 4 weeks
(23.59) year

In-patient Adult (42.53) Recent suicide attempt 32 43 81 4 While in-

and/or SI patient

Kleiman (2018) Community Young adult Suicide attempt in last 54 79 73 Longitudinal Smart phone EMA 4 4 weeks
(23.59) year

In-patient Adult (42.53) Recent suicide attempt 32 43 81 4 While in-

and/or SI patient

Nock (2018) Military Young adult/Adult None 3,916 20 67 Prospective Questionnaire One-time N/A
(NR)

Rizk (2018) Laboratory Adults (33.6) MDD and SI 58 59 45 Experiment Questionnaire One time N/A

Hallensleben In-patient Adults (35.9) MDD and/or lifetime 20 80 NR Longitudinal Smart phone EMA 10 6 days
(2018) SI

Hallensleben In-patient Adults (37.6) MDD and/or lifetime 74 72 NR Longitudinal Smart phone EMA 10 6 days
(2019) SI

Czyz (2019) In-patient Adolescent (NR) suicide attempt in Last 34 76 85 Longitudinal Smart phone 1 2 weeks

Arch Suicide Res. Author manuscript; available in PMC 2023 October 01.
month and/or SI in survey
last week

NR = Not Reported; NSSI = Non-Suicidal Self-Injury; MDD = Major Depressive Disorder; WW = Worst Week
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Table 3.

SI Characteristic Name, Measure and Operational Definition

Author (Year) Name Measure

Reeves et al.

Adapted If yes, what # of Example of Item Item Response Options Scoring Method
from measure? Items
validated Used
measure?
Severity
Witte (2005) & Intensity Yes SPS 36 NR 4-point scale indicating how often Mean Score
Witte (2006) each statement applies

Nock (2009) Intensity Yes SITBS 1 “Rate how intense the urge was to do 5-point-scale from “not present” NR
the behavior you selected” to “very severe”

Kleiman (2017) & Desire to die No NA 1 “How intense is your desire to kill 4-point scale; 0 (not strong Analyzed as reported
Kleiman (2018) yourself right now” [intense] at all) to 4 (very strong
[intense]) scale

Kleiman (2017) & Intensity No NA 3 “How intense is your desire to kill 4-point scale; 0 (not strong Sum score of three
Kleiman (2018) yourself right now” [intense] at all) to 4 (very strong items
[intense]) scale - for each item.

Kleiman (2017) & Intent No NA 1 “How strong is your intention to kill 4-point scale; 0 (not strong Analyzed as reported
Kleiman (2018) yourself right now” [intense] at all) to 4 (very strong
[intense]) scale

Hallensleben (2018) Level of passive SI No NA 2 1) “Life is not worth living for me” 5-point scale from 1 (not at all) to Not analyzed
2) “There are more reasons to die than 5 (very much)
to live for me”

Hallensleben (2018) Level of active SI No NA 2 3) “I’m thinking about taking my own 5-point scale from 1 (not at all) to No analyzed
life” 5 (very much)
4) “I want to die”

Hallensleben (2018) Composite SI No NA 4 1) “Life is not worth living for me” 5-point scale from 1 (not at all) to Total score of four
2) “There are more reasons to die than 5 (very much) items summed (range
to live for me” = 4–20).

Arch Suicide Res. Author manuscript; available in PMC 2023 October 01.
3) “I’m thinking about taking my own
life”
4) “I want to die”

Hallensleben (2019) Level of passive SI No NA 2 1) “Life is not worth living for me” 5-point scale from 1 (not at all) to Not analyzed
2) “There are more reasons to die than 5 (very much)
to live for me”

Hallensleben (2019) Level of active SI No NA 2 3) “I’m thinking about taking my own 5-point scale from 1 (not at all) to No analyzed
life” 5 (very much)
4) “I want to die”

Hallensleben (2019) Composite SI No NA 4 1) “Life is not worth living for me” 5-point scale from 1 (not at all) to Total score of four
2) “There are more reasons to die than 5 (very much) items summed (range
to live for me” = 4–20).
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Author (Year) Name Measure

Adapted If yes, what # of Example of Item Item Response Options Scoring Method
from measure? Items
validated Used
measure?
Reeves et al.

3) “I’m thinking about taking my own

life”
4) “I want to die”

Nock (2018) Self-Injurious Yes C-SSRS 3 “Did you ever make a suicide attempt; NR Composite Score of 3
Thoughts and that is, purposefully hurt yourself items
Behavior with at least some intention to die?”

Czyz (2019) Urge Severity Yes (Nock et al., 1 “How strong was the urge to act on Scale from 1 (low) to 7 (high) Analyzed as reported
2009) your thoughts of suicide?”

Temporality
Witte (2005) & Duration Yes SPS 36 NR 4-point scale indicating how often Number of days
Witte (2006) each statement applies above a T- score of
70

Witte (2006) Variability Yes SPS 36 NR 4-point scale indicating how often 1
each statement applies MSSD statistic

Nock (2009) Frequency Yes SITBS 1 “Are you having thoughts of self- Yes/no Number of yes
destructive behavior” responses

Nock (2009) Duration Yes SITBS 1 “Indicate how long you thought about 6-point-scale from “<5 seconds” Analyzed as reported
doing the behavior” to “5- hrs to 1-day”

Kleiman (2017) & Frequency No NA 1 “How intense is your desire to kill 4-point scale; 0 (not strong Number of non-zero
Kleiman (2018) yourself right now?” [intense] at all) to 4 (very strong answers
[intense]) scale

Nock (2018) Duration Yes C-SSRS 2 “How many days during worst week NR Analyzed as reported
did you have SI” and “How long did
those thoughts usually last when you
had them?”

Rizk (2018) Duration Yes BSSI (Item 6) 1 NR 3 categorical responses: Ideators separated
1) brief, fleeting periods, into two groups 1)

Arch Suicide Res. Author manuscript; available in PMC 2023 October 01.
2) longer periods, and brief ideators and
3) continuous (chronic) or almost 2) longer and
continuous. continuous ideators,
then longer and
continuous ideators
added together to
form second group

Czyz (2019) Duration Yes C-SSRS 1 “How long did these thoughts last?” 5 point-scale, ranged from ‘a few Analyzed as reported
seconds or minutes’ to ‘more than
8 hr/continuous.’

Czyz (2019) Frequency Yes C-SSRS 1 “How many times did you have 4-point scale, ranged from ‘only Analyzed as reported
thoughts of killing yourself” one time’ to ‘all the time.’
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Author (Year) Name Measure

Adapted If yes, what # of Example of Item Item Response Options Scoring Method
from measure? Items
validated Used
measure?
Reeves et al.

Controllability
Kleiman (2017) & Ability to resist No NA 1 “How strong is your ability to resist 4-point scale; 0 (not strong Reverse coded
Kleiman (2018) urge the urge to kill yourself [intense] at all) to 4 (very strong
[intense]) scale

Nock (2018) Controllability Yes C-SSRS 1 “During that worst week, how easy NR Analyzed as reported
was it for you to control those
thoughts?”

Deterrents/Reasons for Ideating

No articles measured characteristics operationally defined to fit under deterrents/reasons for ideating.

SI characteristics were organized into four domains after comparing each characteristic’s measurement and operational definition.

SPS = Suicide Probability Scale; SITBS = Self Injurious Thoughts and Behaviors Survey; BSSI = Beck Scale for Suicidal Ideation; NR = Not Reported; NA = Not Applicable
1
MSSD = Mean Squared Successive Differences

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Table 4.

Validity and reliability of SI characteristic measures

Author (Year) Name Measure Validity Reliability

Reeves et al.

Adapted from validated Content/Face Criterion-Related *Internal Consistency Test-Retest

measure? (Name of measure) Validity Validity
Witte (2005) Intensity Yes (SPS) 1 1 1 1

Duration Yes (SPS) 1 1 1 1

Witte (2006) Intensity Yes (SPS) 1 1 1 1

Duration Yes (SPS) 1 1 1 1

Variability Yes (SPS) 1 1 1 1

Nock (2009) Frequency Yes (SITBS) 1 1 NA 1

Intensity Yes (SITBS) 1 1 NA 1

Duration Yes (SITBS) 1 1 NA 1

Kleinman (2017) & Kleinman (2018) Frequency No 0 0 NA 0

Desire to die No 0 0 NA 0

Intent No 0 0 NA 0

Ability to resist urge No 0 0 NA 0

Intensity No 0 0 0 0

Nock (2018) Duration Yes (C-SSRS) 1 1 1 1

Controllability Yes (C-SSRS) 1 1 NA 1

Self-Injurious Thoughts and Yes (C-SSRS) 1 1 1 1

Behavior

Rizk (2018) Duration Yes (BSSI) 1 1 NA 1

Arch Suicide Res. Author manuscript; available in PMC 2023 October 01.
Hallensleben (2018) Level of passive SI No 0 0 0 0
&
Hallensleben (2019) Level of active SI No 0 0 0 0

Composite SI No 0 0 0 0

Czyz (2019) Duration Yes (C-SSRS) 1 1 NA 1

Frequency Yes (C-SSRS) 1 1 NA 1

Urge Severity Yes (C-SSRS) 1 1 NA 1

0 = study did not mention the validity or reliability of the measure used for the corresponding SI characteristic.

1 = sufficient validity or reliability reported for SI measure, but not for measure of SI characteristic.
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2= sufficient validity or reliability reported for the specific SI characteristic measure.

SPS = Suicide Probability Scale; SITBS = Self Injurious Thoughts and Behaviors Survey; BSSI = Beck Scale for Suicidal Ideation

NA = Not Applicable
*
Internal consistency is not relevant to single item measures
Reeves et al.

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Table 5.

Comparison of SI Characteristic Name and Definitions to C-SSRS

Author (Year) Severity Intensity

Reeves et al.

“The strength of feeling during Frequency Duration Controllability Deterrents Reason for
which one contemplates acting Ideating
on suicidal thoughts.” “How often one experience “The length of a continuous “The ease at which one could stop “The presence
suicidal thoughts.” suicidal thought.” themselves from considering suicide.” of a person or “The
thing which reason for
stops one from thoughts of
wanting to die suicide.”
or commit
suicide.”

Was Was the name Was Was the Was Was the Was Did they use Was Was
‘severity’ severity used? ‘frequency’ name ‘duration’ name ‘controllability’ the name ‘deterrents’ ‘reason for
defined (If not, what defined frequency defined ‘duration’ defined similarly ‘controllability’? defined ideating’
similarly to label was similarly to used? similarly to used? to definition (If not, what label similarly to defined
definition used?) definition (If not, definition (If not, what above? was used? definition similarly to
above? above? what label above? label was above? definition
was used?) used?) above?
Witte (2005) Yes No Yes No No NA No NA No No
(Intensity) (Duration)
Witte (2006)

Nock (2009) Yes No Yes Yes Yes Yes No NA No No

(Intensity)

Kleinman Yes No Yes Yes No No Yes No No No

(2017) (SI) (Ability to resist
(Desire) urge)
Kleinman (Intention)
(2018)

Nock (2018) Yes No Yes No Yes Yes Yes Yes No No

(SITB) (Duration)

Rizk (2018) No NA No NA Yes Yes No NA No No

Arch Suicide Res. Author manuscript; available in PMC 2023 October 01.
Hallensleben Yes No No NA No NA No NA No No
(2018) (Level)

Hallensleben
(2019)

Czyz (2019) Yes No Yes Yes Yes Yes No NA No No

(Urge severity)

C-SSRS = Columbia Suicide Severity Rating Scale; SI = Suicidal Ideation; SITB = self-injurious thoughts and behaviors.

Dark Blue = studies that used the same name as the C-SSRS to describe the corresponding characteristic as operationally defined by the C-SSRS.

Light Blue = studies that did not use the same name as the C-SSRS to describe the corresponding characteristics as operationalized by the C-SSRS.
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