PELOD-2: An Update of the PEdiatric Logistic

Organ Dysfunction Score

Stphane Leteurtre, MD, PhD''^; Alain Duhamel, PhD^'^; Julia SaUeron-'^; Bruno Grandbastien,
Jacques Lacroix, MD'; Francis Leclerc, MD, PhD^'^ on behalf of the Groupe Francophone de
Ranimation et d'Urgences Pdiatriques (GFRUP)

Objective: Multiple organ dysfunction syndrome Is the nnain cause Setting: Nine hiultidisciplinary, tertiary-care PICUs of university-
of death in adult ICUs and in PICUs. The PEdiatric Logistic Organ affiliated hospitals in France and Belgium.
Dysfunction score developed in 1999 was primarily designed Patients: All consecutive children admitted to these PICUs (June
to describe the severity of organ dysfunction. This study was
2006-October 2007).
undertaken to update and improve the PEdiatric Logistic Organ
Intervention: None.
Dysfunction score, using a larger and more recent dataset.
Measurements and Main Resuits: We collected data on variables
Design: Prospective multicenter cohort study.
considered for the PEdiatric Logistic Organ Dysfunction-2 score
during PICU stay up to eight time points: days 1, 2, 5, 8, 12,
'Pdiatrie Intensive Care Unit, Jeanne de Flandre university Hospital, Lille, 16, and 18, plus PICU discharge. For each variable considered
France.
for the PEdiatric Logistic Organ Dysfunction-2 score, the most
^UDSL, Univ Lille Nord de France, Lille, France.
abnormal value observed during time points was collected. The
^Department of Biostatistics, CHU Lille, Lille, France.
outcome was vital status at PICU discharge. Identification of the
"Department of Epidemiology and Public Health, Calmette University
Hospital, Lille, France. best variable cutoffs was performed using bivariate analyses. The
^Pdiatrie Intensive Care Unit, Sainte-Justine Hospital, Universit de PEdiatric Logistic Organ Dysfunction-2 score was developed
Montral, Montral, Canada.
by multivariable logistic regressions and bootstrap process. We
Authors belonging to Groupe VALIDscore of the GFRUP: D. Biarent
(Bruxelles, Belgium), R. Cremer (Lille, France); S. Dauger (Robert used areas under the receiver-operating characteristic curve to
Debr-Paris, France), M. Dobrzynski (Brest, France), G. Emriaud evaluate discrimination and Hosmer-Lemeshow goodness-of-
(Grenoble, France), S. Renolleau (Trousseau-Paris, France), M. Roque-
Gineste (Toulouse, France), D. Stamm, N. Richard (Lyon, France), and I.
fit tests to evaluate calibration. We enrolled 3,671 consecutive
Wroblewski (Besanon, France). patients (median age, 15.5 mo; interquartile range, 2.2-70.7).
All authors contributed to the study design drafted by Dr. Leteurtre. Mortality rate was 6.0% (222 deaths). The PEdiatric Logistic
Drs. Leteurtre, Grandbastien, and Leclerc contributed to the clinical
implementation of the study and supervision of the patients. Dr. Duhamel Organ Dysfunction-2 score includes ten variables corresponding
and Mr. Salieron designed and did the statistical analysis and verified to five organ dysfunctions. Discrimination (areas under the
its accuracy. Dr.' Leclerc obtained funding and supervised the study. Dr.
Leteurtre, Dr. Duharnel, Ms. Salieron, Dr. Grandbastien, and Dr. Leclerc
receiver-operating characteristic curve = 0.934) and calibration
had full access to all data. All authors helped draft this report or critically (chi-square test for goodness-of-fit = 9.31, p = 0.317) of the
revised the draft. All authors reviewed and approved the final version of the
report and had final responsibility for the decision to submit for publication.
PEdiatric Logistic Organ Dysfunction-2 score were good.
Conciusion: We developed and validated the PEdiatric Logistic
Supplemental digital content is available for this article. Direct URL
citations appear in the printed text and are provided in the HTML and PDF Organ Dysfunction-2 score, which allows assessment of the severity
versions of this article on the journal's website (http://journals.lww.com/
of cases of multiple organ dysfunction syndrome in the PICU with
ccmjournal).
Supported, in part, by grant from the French Ministry of Health. a continuous scale. The PEdiatric Logistic Organ Dysfunction-2
The sponsors of the study and the funding source had no role in the study score now includes mean arterial pressure and lactatemia in the
design, data collection, data analysis, data Interpretation, writing of the cardiovascular dysfunction and does not include hepatic dysfunction.
manuscript, or in the decision to submit to publication.
The score will be in the public domain, which means that it can be
The authors have disclosed that they do not have any potential conflicts
of interest. freely used in clinical trials. {Crit Care Med 2013; 41:1761 -1773)
For information regarding this article. E-mail: stephane.leteurtre@chru-lille.fr Key Wonis: intensive care units; multiple organ failure; outcome
Copyright 2013 by the Society of Critical Care Medicine and Lippincott assessment; pdiatrie; scoring methods; severity of illness index
Williams & Wilkins
DOI: 10.1097/CCM.ObOI 3e31828a2bbd

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Leteurtre et al

February 7,2007. The study design was approved by the ethics

D
eseribing the severity of illness of eritically ill patients
while they are in an ICU is very important: Reliable committee of the Socit de Ranimation de Langue Franaise
quality assurance and quality assessment cannot be on April 27, 2007.
done without such data. Eurthermore, an accurate marker of
severity of illness can be used as an outcome measure in clinical Item Selection
studies. Multiple organ dysfunction syndrome (MODS), defined The variables used to create and validate the PELOD-2 were-
as the presence of two or more organ dysfunctions, is a good abstracted from the PELOD (Glasgow Coma Score, pupillary
candidate marker of severity of illness because MODS is the reactions, heart rate, systolic blood pressure, creatinine,
mahl cause of death in adult ICU (1) and in PICU patients (2,3). Pao^/FiOj, PacOj, meehanieal ventilation, WBCs, platelets,
Several definitions of organ dysfunctions and several sets aspartate transaminase, prothrombin time, and international
of diagnostic criteria of MODS have been published (4-6). normalized ratio) and the P-MODS (laetate, Pao^/Fio^,
In the PICU, the relationship between the number of organ bilirubin, fibrinogen, and blood urea nitrogen) seores (2, 8).
dysfunction, which is somewhat quantitative, and mortality is Furthermore, the mean arterial pressure, whieh is an item of
better than it is between the presence or absence of MODS, the SOFA seore for adults, was added because it is considered a
which is dichotomous, and mortality (2, 6). Furthermore, good marker of organ perfusion (9).
it is important to develop scores that consider the higher
and the lower risk of death associated with the different Data Management
organ dysfunctions (2). Adult MODS scores were developed Patients were monitored until they died or were discharged from
using mortality as a dependent variable (7, 8). It is with the PICU, whichever happened first. Our team of investigators
these considerations in mind, the Pediatric-Multiple Organ showed in 2010 that one does not need to collect data on the
Dysinction Score (P-MODS) (9), the PEdiatric Logistic items of the PELOD everyday: Thus, we collected data during
Organ Dysfunction (PELOD) score (2,10,11), and a modified PICU stay according to the set of 8 days (days 1, 2, 5, 8, 12,
Sequential Organ Failure Assessment (SOFA) score for children 16, and 18, plus the discharge day) that were identified as the
were created (12). The PELOD was developed in 1999, more optimal time points to estimate the daily PELOD (dPELOD)
than a decade ago ( 10). It is by far the most frequently used score scores (16). Days were counted by 24-hour interval, from the
aiming to describe the severity of cases of P-MODS. Because time of admission to 24 hours afrer admission and so on.
of changes over time in case mix and chnical practice, the Variables were measured only if the attending physician thought
performance of prognostic and descriptive models deteriorate, it appropriate (i.e., if justified by elinieal status of patient). If a
and there is a need to re-calibrate them (13). Furthermore, the variable was not measured, we assumed that it was identical to
PELOD was notfreeof some limitations; for example, a Brazilian the previous measurement (i.e., the physician thought the value
study reported that the PELOD kept a very good discriminative of the variable had not changed) or normal (i.e., the physician
capacity in Brazilian PICUs, but its calibration was poor (14). thought the value of the variable was normal). Physiologic data
Also, even though PELOD is quantitative, it is discontinuous, from the preterminal period (the last 4 hr of Hfe) were discarded
which may cause problems when doing some statistical analyses ( 17). As for previously published severity and MODS scores, the
(15). This study was undertaken to update and to improve the most abnormal value of each variable observed during each of
PELOD score, using a larger and more recent dataset. these time points was considered to build the PELOD-2 score.
Clinical data were prospectively recorded on a standardized
case-report form. Previously trained physicians (one per
METHODS center) entered data into a web-based database respecting
The 33 university-affiliated PICUs that were members of confidentiality requirements (Epiconcept, Paris, France). A
the Groupe Francophone de Ranimation et Urgences research assistant screened the database weekly for quality
Pdiatriques (GFRUP) were invited to participate: nine PICUs control and, if needed, sent a report to investigators. One
provided, on a voluntary basis, the information requested quality control visit was done in each center during the study.
(eight in France and one in Belgium). All consecutive children Patients' data were collected anonymously, but investigators
admitted to these PICUs between June 21, 2006, and October held a nominal list for quality control.
31,2007, were included. Children with a history of prematurity
and hospitalized afrer birth were enrolled. Patients over 18 Statistical Analysis
years and newborns who were premature (< 37-wk gestation) Identification ofCovariates and Their Cutoff. The association
and admitted at birth were excluded. Although the period of between the outcome (death/survival at PICU discharge) and
data collection varied between units, for each unit, all patients each variable was first investigated using bivariate logistic
admitted consecutively during the study period were included. regression. As the log-Unearity assumption for continuous
variables was not verified, they were transformed in categorical
Ethical Considerations variables. This transformation process took into account two
The PELOD score does not require that more measurements groups of variables according to literature data: those for which
be done than in standard practice. The study and its database the normal values depend on the patient's age (namely heart
were declared safe and were approved by the French authorities rate, systolic and mean arterial pressure, and ereatinine) and
(Commission Nationale de l'Informatique et des Liberts) on the others. The cutoffs were identified by using a decision tree

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 Pdiatrie Criticai Care

procedure with the Chaid method (14). The final cutoff values TABLE 1. Baseline and Clinical Characteristics,
were validated on the hasis of their clinical relevance, the results of
Reason for Admission and Primary Disease
the bivariate logistic regression, and the existence of a monotone
relation between the death rates and the levels of the categorized at Entry, and Outcomes of Children Admitted
variables (supplemental data, Supplemental Digital Content 1, to Nine PICUs (June 2006-October 2007)
http://links.lww.com/CCM/A639).
Characteristics and Outcomes Value
Identification of the Predictive Model. A multivariable
logistic regression was performed with all variables (full Baseline characteristics
model). The simplification of this full model was done using Gender (male), n (%) 2,097(571)
another multivariable logistic regression with backward Age (mo), median (iQR) 15.5 (2.2; 70.7)
selection at the level p = 0.05. The stability of the selected model
0 to < 1, n (%) 627(17.1)
was investigated using the bootstrap resampling method (16)
(supplemental data. Supplemental Digital Content 1, http:// 1-11,n(%) 1,068(29.1)
links.lww.com/CCM/A639). 12-23,n(%) 399(10.9)
Creation of the PELOD-2 Score. For some categorized 24-59, n (%) 559(15.2)
variables, some levels were pooled according to the odds ratio
60-143, n(%) 562(15.3)
estimates. All cutoff values were rounded to the nearest integer
to have a user-friendly score. The model was rebuilt considering ^ 144, n (%) 456(12.4)
these simphfications (supplemental data, Supplemental Digital Recovery post procedure," n (%) 955 (26.0)
Content 1, http://links.lww.com/CCM/A639). The PELOD-2
Pdiatrie Index of Mortalily 2 score 1.42 (0.78; 4.34)
was obtained from the coefficients of this final multivariable
(predicted death rate in %) median (IQR)
logistic regression. The coefficients were multiplied by two and
rounded to the nearest integer to have a user-friendJy score. Primary reason for PICU admission, n (%)
Validation. The comparison of the PELOD-2 between the Respiratory 1,664(46.6)
two groups (death/survival) was performed by a Student test. Neurologic 662(18.5)
The discriminant power of the PELOD-2 score was estimated Cardiovascular 673(18.8)
using the area under the receiver-operating curve (AUC)
Hepatic 40(1.1)
with 95% CI, and calibration was assessed using the Hosmer-
Lemeshow chi-square test. We addressed the optimism bias Genitourinary 96 (2.7)
using a bootstrap resampling method. The stabihty of the score Gastrointestinal 205 (5.7)
was estimated by cross validation (17) (supplemental data. Endocrine 57(1.6)
Supplemental Digital Content 1, http://links.lww.com/CCM/
A639). We used a logistic regression to investigate the relation Musculoskeletal 45(1.3)
between each organ dysfunction and mortality. We used a Hmatologie 45(1.3)
stepwise multiple regression to evaluate the relative weight of Miscellaneous/undetermined 99 (2.7)
each organ dysfunction on the PELOD-2 scoring system. For
Mixed 85(2.4)
these two analyses, the independent variables were ordinal
variables of each organ dysfunction. Cause of primary diseases at entry, n (%)
Infection 863 (23.5)
Comparison Between thePELOD andPELOD-2 Scores. The
PELOD score was computed and calibrated using a logistic Trauma 325 (8.9)
regression to compare distribution and AUC of both scores. Congenital disease 1,123(31.0)
The results are expressed by medians and interquartile Drug poisoning 72 (2.0)
ranges (IQR) or means and SD for continuous variables and by
Cancer 120(3.3)
frequencies and percentages for categorical variables. Statistical
analyses were performed using SAS software version 9.2 (SAS Diabetes 41 (1.1)
Institute, Cary, NC). A p value of less than 0.05 was considered Allergic/immunologic diseases 55(1.5)
statistically significant.
Miscellaneous/undetermined 1,072(29.2)
Elective PICU admission," n (%) 970 (26.4)
RESULTS
Outcomes
The nine participating PICUs were devoted to medical,
trauma, and postoperative care (including cardiac surgery) Mechanical ventilation, n (%) 1,926 (52.5)
and were representative of the 33 university-affiliated PICUs Length of ICU stay (d), median (IQR) 2(1;5)
of the CFRUP in terms of recruitment (medical/surgical, Mortality, n (%) 222 (6.0)
neonatal/pediatric) (supplemental data. Supplemental Digital
According to Pdiatrie Index of Mortality 2 instructions.
Content 1, http://links.lww.com/CCM/A639 for details on the Total number of patients included in the study are 3,671.
nine participating and the 24 nonparticipating sites). Patients IQR = interquartile range.

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Leteurtre et al

were enrolled for a median period of 15 months (IQR, 7-16). in Table 5. Finally, the PELQD-2 includes 10 variables involving
The median number of admissions per PICU during the study five organ dysfunetions. For eaeh variable, the severity level is
period was 442 (IQR, 132-581). ranging from 0 (normal) to a maximum of 6 (Table 6).
Among 3,675 consecutively screened chudren, two older than The AUC of the PELOD-2 was 0-942 (95% CI, 0.925-
18 years and two with incomplete data were excluded. Thus, 0.960). The ealibration assessed by the Hosmer-Lemeshow ehi-
3,671 patients were retained for analysis, including 222 who square test was equal to 6.74 (p = 0.565) (supplemental data.
died in the PICU (mortality rate, 6.0%). Baseline characteristics Supplemental Digital Content 1, http://links.lww.eom/CCM/
and outcomes of the enrolled population are detailed in A639). After correction for the optimism bias, the AUC and the
Table 1. The proportion of medical and surgical cases was 66.5% calibration of the PELQD-2 were 0.934 and 9.31 (p = 0.317),
to 33.5%. The median age was 15.5 months (IQR, 2.2-70.7). respectively. The cross validation covariate was associated with
The bivariate analyses demonstrated that all the candidate a value of 0.89 close to 1.
variables were predictive of death except bilirubin (p = 0.53); Median PELOD-2 score was 4 (IQR, 2-7); mean PELQD-2
these 17 significant variables are listed with their cutoffs in score was 4.8 (SD, 4.3). PELOD-2 was significantly (p < 0.0001)
Tables 2 and 3. Mean arterial pressure and systolic blood pressure higher in nonsurvivors than in survivors (mean, 14.9 [SD, 6.1]
provided simuar information; we selected mean arterial pressure vs mean, 4.2 [SD, 3.2], respectively).
to describe cardiovascular dysfunction. The results of the All organ dysfunctions retained in the PELOD-2 seore were
multivariable logistic regression performed on these 16 variables elosely related to the risk of mortality. The maxinium points
are reported in the supplemental data (Supplemental Digital for eaeh organ ranged between 2 and 10. Neurologie and
Content 1, http://links.lww.com/CCM/A639) (ftill model). respiratory dysfunetions were the most important markers,
After backward selection with bootstrap validation, 10 variables explaining, respeetively, 48% and 29% of the varianee with
were retained (Table 4). From the results of this multivariable respeet to the risk of mortality (Table 7). Figure 1 shows the
analysis, the following levels were pooled with the reference level: distribution of patients for eaeh organ dysfunetion.
lactatemia (mmol/L) between 3.97 and 5.37, Pao^ (mm Hg)/ Five hundred fifty-six (15%) patients had no organ
FiOj ratio between 60.5 and 136.3, noninvasive ventilation, and dysfunetion, 1,016 (28%) patients had one, 994 (27%)
WBC count (x lO'/L) between 2.15 and 4.09 (significant level patients had two, and 1,105 (30%) patients had three or more.
> 0.2). For creatinine, the two levels of risk had nearly equal Table 8 shows mean PELOD-2 seores and outeome stratified
odds ratio values (2.42 and 2.90, respectively); they were pooled by number of organ dysfunetions.
in a unique class (^ cutoff 1). All cutoff values were rounded The distribution of the PELQD-2 is different fi-om that of
to be more user ftiendly, when appropriate. The final logistic the PELQD: The PELQD-2 is a eontinuous seore that ean take
regression, which considered these simplifications, is detailed all integer values ftom 0 to 33 (Fig. 2). The value of the AUC of

TABLE 2. Identification of Cutoff Values for Age-Dependent Variables

Age (mo)

Variable and Cutoff 12-23 24-59 60-143 ^ 144

Creatinine (jimol/L)
Cutoff 1 70 22 34 50 58 93
Cutoff 2 94 47 59 75 83 117
Heart rate (beats/min)
Cutoff 207 215 203 191 176 167
Mean arterial pressure (mm Hg)
Cutoff 1 16 25 30 32 35 37
Cutoff 2 30 39 44 46 49 51
Cutoff 3 46 55 60 62 65 67
Systolic arterial pressure (mm Hg)
Cutoff 1 22 38 47 49 54 58
Cutoff 2 34 49 58 60 65 69-
Cutoff 3 43 58 67 69 74 78
Cutoff 4 52 68 76 79 84 87
Cutoff 5 63 79 87 90 95 98

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TABLE 3. Candidate Variables for the Pdiatrie Logistic Organ Dysfunction-2 Score
variable Survivors (n = 3,4

Non-age-dependent variables
Glasgow Coma Score
3-4 53(1.54) 103(46.61)
5-10 337 (9.77) 28(12.67) < 0.001
S11 3,059 (88.69) 91 (40.99)
Pupillary reaction
Both fixed 37(1.07) 108(48.65)
Both reactive 108(98.93) 114(51.35) < 0.001
Lactatemia (mmol/L)
<3.97 3,121 (90.49) 106(47.75)
3.97-5.36 158(4.58) 20(9.01)
5.37-11.06 136(3.94) 43(19.37) < 0.0001
^11.07 34 (0.99) 53 (23.87)
Uremia (mg/dL)
<27 2,205 (63.93) 71 (31.98)
27-36 595(17.25) 29(13.06) < 0.0001
^37 649(18.82) 122(54.95)
PaOj (mm Hg)/FiO2 ratio

<60.5 81 (2.35) 47(21.27)

60.5-136.2 250 (725) 23(10.41) < 0.001
^ 136.3 3,118(90.40) 152(68.47)
PacOj (mm Hg)

<58.5 3,099 (89.85) 155(69.82)

58:5-94 315(9.13) 49 (22.07) < 0.000 f
^ 94.5 35(1.01) 18(8.11)
Ventilation
No 1,470(42.62) 10(4.50)
Noninvasive 261 (757) 4(1.80) < 0.001
Invasive 1,718(49.81) 208 (93.69)
WBC count (x 10VL)
<2.15 85 (2.46) 34(15.32)
2.15-4.0 170 (4.93) 21 (9.46) < 0.0001
^4.1 3,194(92.61) 167 (75.23)
Platelets (x 10VL)
<76.5 237 (6.87) 72 (32.43)
76.5-141 287 (8.32) 36(16.22) < 0.0001
141.5 2,925(84.81) 114(51.35)

{Continued)

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TABLE 3. (Continued). Candidate Variables for the Pdiatrie Logistic Organ

Dysfunction-2 Score
Variable Survivors (n = 3,449) (%) Nonsurvivors (n = 222) (%)
Fibrinogen (mg/dL)
92 (2.67) 31 (13.96)
81-146 156 (4.52) 32(14.41) < 0.0001
^147 3,201 (92.81) 159(71.62)
Aspartate transaminase (lU/L)
< 111.5 3,102(89.94) 122(54.95)
111.5 to < 339.5 235(6.81) 48(21.62) < 0.0001
S 340 112(3.25) 52 (23.42)
Prothrombin time (s)
< 34.5 110(3.19) 61 (27.60)
34.5-55 335(9.71) , 56 (25.34)
55.5-69 418(12.12) 29(13.12) < 0.001
^69.5 2,586 (74.98) 76 (34.23)
International normalized ratio
<3 3,429 (99.42) 217(97.75)
^3 20 (0.58) 5 (2.25) 0.0149
Age-dependent variables^
Mean arterial pressure (mm Hg)
< Cutoff 1 21 (0.61) 39(17.57)
Cutoff 1 -cutoff 2 276 (8.0) 69(31.08) < 0.0001
Cutoff 2-cutoff 3[ 1,654(47.96) 95 (42.79)
^ Cutoff 3 1,498(43.43) 19(8.56)
Systolic arterial pressure (mm Hg)
< Cutoff 1 15(0.43) 42(18.92)
Cutoff 1 -cutoff 2 58(1.68) 33(14.86)
Cutoff 2-cutoff 3 193(5.60) 38(1712) < 0.0001
Cutoff 3-cutoff 4 519(15.05) 47(21.17)
Cutoff 4-c.utoff 5 1,057 (30.65) 45 (20.27)
^ Cutoff 5 . 1,607(46.59) 17 (766)
Heart rate (beats/min)
< Cutoff 1 3,286 (95.27) 180(81.08) < 0.0001
^ Cutoff 1 163(4.73) 42(18.92)
Creatinine (jjmol/L)
< Cutoff 1 2,255 (65.38) 49 (22.07)
Cutoff 1-cutoff 2 785 (22.76) 73 (32.88) < 0.0001
^ Cutoff 2 409(11.86) 100(45.05)
"Cutoff of age-dependent variables is described in Table 2.
Reference levels are in bold font.

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TABLE 4. Muitivariable Logistic Regression After Backward Selection With Bootstrap Validation
Odds Ratio
Variable and Cutoff Coefficient (95% CD
Glasgow Coma Score
11
5-10 0.635 1.89(1.12-3.18) 0.017
3-4 1.904 6.71 (3.58-12.59) < 0.0001
Pupillary reaction
Both reactive 1
Both fixed 2.481 11.95(6.48-22.03) < 0.0001
Lactatemia (mmol/L)
<3.97 1
3.97-5.37 0.326 1.39(0.70-2.74) 0.347
5.37-11.07 0.642 . 1.90(1.05-3.43) 0.033
> 11.07 1.814 6.13(2.93-12.83) < 0.0001
Mean arterial pressure (mm Hg)
2: Cutoff 3" 1
Cutoff 2-eutoff 3= 0.841 2.32(1.28-4.18) 0.005
Cutoff 1 -cutoff 2^ 1.372 3.94 (2.00-779) < 0.0001
< Cutoff 1 = 2.961 19.31 (6.88-54.21) < 0.0001
Creatinine (pmol/L)
< Cutoff 1 = 1
Cutoff 1 -cutoff 2^ 0.883 2.42(1.49-3.94) < 0.0001
^ Cutoff 2' 1.065 2.90(1.69-4.99) < 0.0001
PaOj (mm Hg)/FiO2 ratio
> 136.3 1
60.5-136.3 -0.197 0.82(0.44-1.53) 0.535
<60.5 0.889 2.43(1.27-4.67) 0.008
PacOj (mm Hg)
<58.5 1
58.5-94.4 0.529 1.70(1.00-2.88) 0.050
^94.5 1.604 4.97(1.94-12.76) 0.001
Ventilation,
No ventilation 1
Noninvasive ventilation, yes 0.166 1.18(0.28-5.05) 0.823
Invasive ventilation, yes 1.446 4.25 (2.02-8.93) < 0.0001
WBC count (x 10VL)
^4.10 1
2.15-4.09 -0.276 0.76(0.36-1.60) 0.468
<2.15 0.693 2.00(0.95-4.19) 0.067
Platelets (x 10VL)
^ 141.5 1 .
76.5-141.4 0.399 1.49(0.84-2.64) 0.172
<76.5 0.782 2.19(1.27-3.77) 0.005
'Cutoffs of age-dependent variables are defined in Table 2.

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TABLE 5. Final Logistic Regression Defining the Pdiatrie Logistic Organ

Dysfunction-2 Score
Type of Variables Odds Ratio Pdiatrie Logistic Organ
and Cutoffs Coefficient (95% CI) P Dysfunction-2 Points
Glasgow Coma Score
1
1

5-10 0.650 1.92(1.14-3.22) 0.014 1 .

3-4 1.942 6.97(3.74-12.99) < 0.0001 4
Pupillary reaction
Both reactive 1
Both fixed 2.510 12.30(6.68-22.65) <o!oooi 5
Lactatemia (mmol/L)
<5.0 1
5.0-10.9 0.508 1.66(0.98-2.83) 0.062 1
11.0 1.804 6.07(3.08-11.96) < 0.0001 4
Mean arterial pressure (mm Hg)
Cutoff 3" 1
Cutoff 2-cutoff 3" 0.806 2.24(1.25-4.02) 0.007 2
Cutoff 1 -cutoff 2" 1.332 3.79(1.93-7.43) < 0.0001 3
< Cutoff 1" 2.891 18.01 (6.52-49.77) < 0.0001 6
Creatinine (jimol/L)
< Cutoff 1" , 1
Cutoff 1" 0.959 2.61 (1.68-4.06) < 0.0001 2
PaOj (mm Hg)/FiO2 ratio -

61 1
^60 0.964 2.62(1.39-4.94) 0.003 2
PacOj (mm Hg)

^58 1
59-94 0.484 1.62(0.97-2.73) 0.068 1
95 1.514 4.55(1.79-11.52) 0.001 3
Ventilation
No or noninvasive 1
Invasive 1.384 3.99 (2.07-770) < 0.0001 3
WBC count (x 10VL)
>2 1
^2 0.761 2.14(1.04-4.40) 0.039 2
Platelets (x 10VL)
142 1
77-141 0-373 1.45(0.82-2.57) 0.200 1
^76 0-782 2.19(1.30-3.67) 0.003 2
Cutoffs of age-dependent variables are defined in Table 2.

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 Pdiatrie Critieal Care

TABLE 6. Scoring the Pdiatrie Logistic Organ Dysfunction-2 Score

Points by Severity Levis
Organ Dysfunetions
and Variables^ 0
Neurologic''
Glasgow Coma Score ^ 11 5-10 3-4
Pupillary reaction Both reactive Both fixed
Cardiovascular^
Lactatemia (mmol/L) <5.0 5.0-10.9 11.0
Mean arterial pressure (mm Hg)
0 to < 1 mo ^46 31-45 17-30 16
1-11 mo ^55 39-54 25-38 24
12-23 mo ^60 44-59 31-43 30
24-59 mo ^62 46-61 32-44 31
60-143 mo ^65 49-64 36-48 35
^ 1 4 4 mo ^67 52-66 38-51 37
Renal
Creatinine (pmoL/L)
0 to < 1 mo 69
1-11 mo 22 23
12-23 mo 34
24-59 mo 50
60-143 mo 58 2:59
^ 144 mo 92
Respiratory''
PaOj (mm Hg)/FiO5 ^61 60
PacOj (mm Hg) 58 59-94 ^95
Invasive ventilation No Yes
Hmatologie
WBC count (x 10VL) >2 2
Platelets (x 10VL) ^ 142 77-141 76
'All variables must be collected, but measurements can be done only if justified by the patient's clinical status. If a variable is not measured, it should be
considered normal. If a variable is measured more than once in 24 hr, the vi/orst value is used in calculating the score. FiOj: fraction of inspired oxygen.
"Neurologic dysfunction: Glasgow Coma Score: use the lowest value. If the patient is sedated, record the estimated Glasgow Coma Score before sedation.
Assess only patients with known or suspected acute central nervous system disease. Pupillary reactions: nonreactive pupils must be > 3 mm. Do not assess
after iatrogenic pupillary dilatation.
"Cardiovascular dysfunction: Heart rate anc' mean arterial pressure: do not assess during ciying or iatrogenic agitation.
"Respiratory dysfunction: Pao,: use arterial measurement only. Pao^/FiOj ratio is considered normal in children with cyanotic heart disease. Paco^ can be
measured from arterial, capillary, or venous samples. Invasive ventilation: the use of mask ventilation is not considered invasive ventilation.
Logit (mortality) = -6.61 -t- 0.47 x PELOD-2 score.
Probability of death = 1/(1 -t- exp [-logit(mortality)]).

PELOD-2'was near to the value obtained for the PELOD on the DISCUSSION
training set (0.98 [95% CI, 0.960-0.999], published in 1999) We developed and validated the PELOD-2, a continuous scale
(10). After recalibration on the present data, the AUC of the that allows assessment of thi? seVerity of cases of MODS in
PELOD-2 was significantly higher than the AUC of the PELOD the PICU. This updated version of the PELOD includes 10
0.857 (95% CI, 0.834-0.879), p < 0.0001. variables involvingfiveorgan dysfunctions. Compared with the
Critical Care Medicine vvvvw.ccnnjournal.org 1769
Leteurtre et al

TABLE 7. Relative Contribution of Each Organ Dysfunction to Mortality (Logistic Regression)

and to the Pdiatrie Logistic Organ Dysfunction-2 score (Multiple Regression)
Logistic Regression Multiple Regression
Maximum Value in Each
Dysfunction Dysfunction Partial R^
Neurologic 9 < 0.0001 0.48
Respiratory 8 < 0.0001 0.29
Cardiovascular 10 < 0.0001 0.12
Renal 2 < 0.0001 0.08
Hmatologie 4 < 0.0001 0.03

previous version, the PELOD-2

100 Neurological 100- Cardiovascular now includes mean arterial
pressure and lactatemia in the
80 80-
4 cardiovascular dysfunction,
w 60- 60-
c which are present in the SOFA
-
tie

40- 40- r-| and the P-MODS scores. On

ra
Q. the other hand, the PELOD-2
20- 20-
* does not include hepatic
n
u
i l l ' 1 1
0- - = +- -I-- t - = - l dysfunction, which was part of
0 1 4 5 6 9 0 1 2 3 4 6 7 10 the first version of the PELOD.
PELOD -2 score PELOD 2 score Hepatic dysfunction was linked
n ill! 355 60 39 10 96 n 1457 43 1562 413 63 82 42 with mortality in PELOD but
accounted for in only 0.1% of
its variance (2), and it did not
100 J Respiratory predict death in the P-MODS
100- Renal
80--
(9) score.
^ 80-
To be useful, a descriptive
J 60 60-- index, such as the PELOD-2,
should be clinically credible,
Ira 40 40-
Q.
accurate, user friendly, and
20 20- generalizable and provide
* useful additional information
0- 1 0-1-
to clinicians and scientists (18).
0 2 0 1 2 3 4 5 6 8
PELOD-2 score
What remains to be determined
PELOD-2 score
2304 1367
is if the responsiveness of the
n 1641 88 4 1558 227 63 78 12
PELOD-2 to preventive and/
or therapeutic interventions is
100 T Haematological
good, if so, this will support the
idea that the PELOD-2 can be
used as an outcome measure in
^ 60 -
c randomized clinical trials. The
I-.S 4 0 -
Q.
responsiveness of a test is good
20-
if the test reacts significantly to
active therapeutic approach,
0 - when the response of the test
0 1 2 3 4 is in the right direction and
PELOD-2 score
when the response of the test is
3005 311 271 12 72
proportional to the stimulus,
Figure 1. Patients' distribution and nnortality rate for each organ dysfunction score. Black diamond = mortaWiy as demonstrated for the
rate, PELOD-2 = Pdiatrie Logistic Organ Dysfunction-2. PELOD (19). Thus, it makes

1770 www.ccmjournal.org July 2013 Volume 41 Number 7

 Pdiatrie Critical Care

TABLE 8. Relationship Between the Number of Organ Dysfunctions, the Pdiatrie Logistic
Organ Dysfunction-2 Score, and Mortality
Pdiatrie Logistic Organ Deaths:
Number of Organ Dysfunction-2 score No. of
Dysfunctions No. of Patients (%) Mean (SD) Patients (%)
0 556(15.2) 0 (0.0) 2 (0.4)
1 1,016(27.7) 2.3 (0.8) 3 (0.3)
2 994(271) 4.9(1.3) 12(1.2)
3 687(18.7) 75 (2.0) 49(71)
4 318(8.7) 11.5(4.4) 97 (30.5)
5 100(2.7) 16.8 (5.2) 59 (59.0)

sense to believe that the responsiveness of the PELOD-2 should Physiology and Chronic Health Evaluation system (20), need
be good, but it remains to be proven. to be updated regularly because patients' demographics, disease
Descriptive scores, like the PELOD, and predictive scores, prevalence, monitoring, treatment, and mortality rates change
like the Pdiatrie Risk of Mortalit^^ score (17) and the Acute over time. In the future, scoring systems are likely to become
more complex and dependent on new information technology.
They may require additional variables, adjustment for treatment
A 900 - 1
a limitations, and diagnostic precision (21). For example, a
800 - 0.9
noninvasive variable, such as Spo^/Fio^ ratio instead of Pao^/Fio^
700 - 0.8 TJ
ratio (22), might be considered more appropriate and/or more
obat)ility
patiients

600 - 0.7 informative.

0.6 MODS scores seem to satisfy most criteria proposed
500 -
'S - 0.5 o by Segers et al to assess the validity of a surrogate outcome,
400 - 3 even though some authors underline that surrogate outcome
0.4
1 300 - O
uin|i

rtali

0.3
endpoints have not yet been rigorously validated (23, 24).
200 - There is also evidence that MODS scores (PELOD, SOFA,
100 - 1
ILIT II
0.2
0.1
MOD) can be a useful tool for clinical investigation: MODS
scores are largely used as secondary endpoint and primary
1 11 l'_| 1 r 1 1 1 r l l l ' . i > 1 ' 1 1 J i l l 1 > >. < M 1 111> 11 1 1 1 1
n
u outcome measure when the mortality cannot be used as a
0 10 20 30 40 50 60 primary outcome measure because its incidence rate is too low
PELOD score (25). This is particularly important in PICUs where mortality
rate is much lower than in adult ICUs. In fact, the first version
B 900 - A
1 of the PELOD was used in many large multicenter studies (26-
800 - - 0.9 28). Also, MODS scores may be used to describe the effects of

700 - I 0.8 0
therapy, and most trials now include repeated measures of a
MODS score as part of routine patient assessment (29).
roba

- 0.7
600 - The equation of probability of death that we used while doing
tiei

0.6 g; the goodness-of-fit test (calibration) is given in Table 6. However,

ra 500
a 0.5 o if the risk of death is to be predicted in a population different
0
400 / from that which PELOD-2 was developed and validated, this
ai 0.4 o
.a /
E 300 - /
should be done using customization steps (first or second level
3
/
- 0.3 of customization), as recommended in the hterature (21). Also,
200 -
- 0.2 we would emphasize that the aim of organ dysfuction scores,
100 - such as the P-MODS (9), PELOD (2), SOFA (8), MODS (7), and
U 1.,
0 2 4 6 8 10 12 14 16 18 20 22 24 26 29
- 0.1

0
Logistic Organ Dysfunction (30) scores, is to describe the severity
of illness of critically ill patients and not to predict mortality rate.
This study has some limitations. First, the data in this study were
PELOD-2 score
collected using the set of 8 days (days 1,2,5,8,12,16, and 18, plus
Figure 2. Descriptive characteristics of the Pdiatrie Logistic Organ the PICU discharge) in PICU that were previously identified as
Dysfunction (PELOD) (A) and PELOD-2 (B) scores in the study the optimal time points for measurement of dPELOD (16). Thus,
population. Dotted lines = probability of mortality calculated from the
score according to the values of the score; bars = number of patients an abnormal value of a variable measured on a day outside this set
according to the values of the score. could be missed; in theory, this could cause some underestimation

Critical Care Medicine www.ccmjournal.org 1771

Leteurtre et al

of the seore. However, data of the day of diseharge or death were 5. Proulx F, Fayon M, Farrell CA, et al: Epidemiology of sepsis and
multiple organ dysfunction syndrome in children. Ctiest 1996;
reeorded, and thus, worst values of variables of patients who 109:1033-1037
died were taken into account up to 4 hours before death. Even 6. Wilkinson JD, Pollack MM, Ruttimann UE, et al: Outcome of pdiatrie
though we eonsidered the worst value of each variable over the patients with multiple organ system failure. Crit Care Med 1986;
PICU stay to build the PELOD-2, as performed with other organ 14:271-274
dysfunetion seores for adults (such as the MOD seore of Marshall 7 Marshall JC, Cook DJ, Christou NV, et al: Multiple organ dysfunction
score: A reliable descriptor of a complex clinical outcome. Crit Care
et al [7] and the SOFA score of Vincent et al [8]), this may Med 1995; 23:1638-1652
have exaggerated the discrhnination (AUC). Consequently, an 8. Graciano AL, Baiko JA, Rahn DS, et al: The Pdiatrie Multiple Organ
external validation of the whole PICU stay and dPELOD-2 seores Dysfunetion Score (P-MODS): Development and validation of an
is needed. Second, the PELOD-2 was developed and validated objeetive seale to measure the severity of multiple organ dysfunetion
in eritieally ill ehildren. Crit Care Med 2005; 33:1484-1491
with a dataset that originated from only two eountries (France
9. Vineent JL, Moreno R, Takala J, et al: The SOFA (Sepsis-related
and Belgium). The population of our study was different from Organ Failure Assessment) seore to deseribe organ dysfunction/
U.S. and U.K. populations (31,32). Thus, the extensibility of our failure. On behalf of the Working Group on Sepsis-Related Problems
findings to other countries, particularly to PICUs that receive a of the European Soeiety of Intensive Care Medieine. intensive Care
Med 1996; 22:707-710
higher percentage of cases from the operating room (32), has
10. Leteurtre S, Martinot A, Duhamel A, et al: Development of a pdiatrie
to be verified. Also, because of changes in ease mix and clinical multiple organ dysfunetion seore: Use of two strategies. Med Decis
practice, the performances of prognostie models deteriorate Making-iQQQ; 19:399-410
over time. To counterbalance this deterioration, models often 11. Leteurtre S, Duhamel A, Grandbastien B, et al: Paediatrie logistie
need to be customized (33). Third, interobserver variability organ dysfunetion (PELOD) score. Lancet 2006; 367:897; author
reply 900-902
was not studied for the PELOD-2 and should be evaluated in 12. Shime N, Kageyama K, Ashida H, et al: Application of modified
fiiture studies on new populations. However, using an eleetronic sequential organ failure assessment seore in ehildren after eardiae
cUnical information system with an automated archiving surgery. J Cardiotttorac Vase Anestfi 2001 ; 15:463-468
method intelligently excluding unrehable variables values should 13. Tilford JM, Roberson PK, Lensing S, et al: Differenees in PICU
mortality risk over time. Crit Care Med 1998; 26:1737-1743
deerease the risk of inaccurate data coUeetion (34).
14. Gareia PC, Eulmesekian P, Braneo RG, et al: External validation of
This study has several strengths. First, the data were collected the paediatrie logistie organ dysfunetion seore. intensive Care Med
2010; 36:116-122
from nine typical European multidisciphnary university-
15. Tibby SM: Does PELOD measure organ dysfunetion and is organ
affihated PICUs. Second, the score development used a large funetion a valid surrogate for death? Intensive Care Med 2010;
dataset of 3,671 consecutive patients. Third, it is eontinuous. 36:4-7
Fourth, its adjusted discriminative value is 0.934, whieh is 16. Leteurtre S, Duhamel A, Grandbastien B, et al: Daily estimation of the
considered "exeellent" in the scale advocated by Hanley et al severity of multiple organ dysfunetion syndrome in eritieally ill ehildren.
CMAJ 2010; 182:1181 -1187
(35) to estimate the descriptive value of a test.
17 Pollaek MM, Patel KM, Ruttimann UE: PRISM III: An updated
In summary, we created and validated the PELOD-2, Pdiatrie Risk of Mortality seore. Crit Care Med 1996; 24:743-752
which has an excellent discriminative power. The PELOD-2 18. Altman DG, Royston P: What do we mean by validating a prognostie
seore now ineludes mean arterial pressure and lactatemia in model? Stat Med 2000; 19:453-473
the cardiovascular dysfunction and does not include hepatie 19. Nguyen TC, Han YY, Kiss JE, et al: Intensive plasma exehange
inereases a disintegrin and metalloprotease with thrombospondin
dysfunction. We believe that the PELOD-2 allows assessment of motifs-13 activity and reverses organ dysfunetion in ehildren with
the severity of cases of MODS in the PICU and can be useful as thromboeytopenia-assoeiated multiple organ failure. Crit Care Med
an outcome measure in clinical trials (36). The PELOD-2 will be 2008; 36:2878-2887
available in the public domain, which means that it can be freely 20. Zimmerman JE, Kramer AA, MeNair DS, et al: Intensive eare unit length
of stay: Benchmarking based on Aeute Physiology and Chronie Health
used in clinical trials, as it was the case with the PELOD (37). Evaluation (APACHE) IV. Crit Care Med 2006; 34:2517-2529
21. Zimmerman JE, Kramer AA, MeNair DS, et al: Aeute Physiology
and Chronie Health Evaluation (APACHE) IV: Hospital mortality
ACKNOWLEDGMENTS assessment for today's eritieally ill patients. Crit Care Med 2006;
We thank the patients who volunteered for the study and the 34:1297-1310
clinicians responsible for their day-to-day elinieal eare. 22. Leteurtre S, Dupr M, Dorkenoo A, et al: Assessment of the Pdiatrie
Index of Mortality 2 with the Pao2/Fio2 ratio derived from the SPO2/FO2
ratio: A prospeetive pilot study in a French pdiatrie intensive eare
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