RESEARCH ARTICLE

Risk Factors Associated with Renal

Involvement in Childhood Henoch-Schönlein
Purpura: A Meta-Analysis
Han Chan, Yan-Ling Tang, Xiao-Hang Lv, Gao-Fu Zhang, Mo Wang, Hai-Ping Yang*,
Qiu Li*
Department of Nephrology, Key Laboratory of the Ministry of Education, Children’s Hospital of Chongqing
Medical University, Chongqing, People’s Republic of China

* oyhp0708@163.com (HPY); liqiu809@126.com (QL)

a11111
Abstract

Background and objective

Henoch-Schönlein purpura (HSP) is an important cause of chronic kidney disease in chil-
OPEN ACCESS dren. This meta-analysis identified risk factors associated with renal involvement in child-
Citation: Chan H, Tang Y-L, Lv X-H, Zhang G-F, hood HSP.
Wang M, Yang H-P, et al. (2016) Risk Factors
Associated with Renal Involvement in Childhood
Henoch-Schönlein Purpura: A Meta-Analysis. PLoS Methods
ONE 11(11): e0167346. doi:10.1371/journal. PubMed, Embase, and Web of Science were searched. The quality of all eligible studies
pone.0167346
was assessed using the Newcastle-Ottawa scale criteria. An analysis of possible risk factors
Editor: Gianpaolo Reboldi, Universita degli Studi di was conducted to report the odds ratio (OR) and weighted mean difference (WMD).
Perugia, ITALY

Received: June 14, 2016 Results

Accepted: November 12, 2016 Thirteen studies (2398 children) revealed 20 possible and 13 significant risk factors associ-
Published: November 30, 2016 ated with renal involvement in HSP, with the following meta-analysis estimates of OR and
Copyright: © 2016 Chan et al. This is an open WMD, with 95% confidence intervals: older age (0.90, 0.61–1.19); age > 10 y (3.13, 1.39–
access article distributed under the terms of the 7.07); male gender (1.36, 1.07–1.74); abdominal pain (1.94,1.24–3.04); gastrointestinal
Creative Commons Attribution License, which bleeding (1.86, 1.30–2.65); severe bowel angina (3.38, 1.17–9.80); persistent purpura
permits unrestricted use, distribution, and
(4.02, 1.22–13.25); relapse (4.70, 2.42–9.14); WBC > 15 × 109/L (2.42, 1.39–4.22); platelets
reproduction in any medium, provided the original
author and source are credited. > 500 × 109/L (2.98, 1.22–7.25); elevated antistreptolysin O (ASO) (2.17, 1.29–3.64); and
decreased complement component 3 (C3) (3.13, 1.62–6.05). Factors not significantly asso-
Data Availability Statement: All relevant data are
within the paper and its Supporting Information ciated with renal involvement were: blood pressure; orchitis; elevated C-reactive protein;
files. elevated erythrocyte sedimentation rate (ESR); and elevated serum IgA/IgE or IgG. Arthri-
Funding: This work was supported by the National tis/arthralgia may be a risk factor according to the criteria of the American College of Rheu-
Natural Science Foundation of China (Grant matology (1.41, 1.01–1.96).
numbers 81270802, 81470946, 81200520),
https://isisn.nsfc.gov.cn/egrantindex/funcindex/
prjsearch-list. Conclusion
Competing Interests: The authors have declared The following are associated with renal involvement in pediatric HSP: male gender; > 10 y
that no competing interests exist. old; severe gastrointestinal symptoms (abdominal pain, gastrointestinal bleeding, and

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 Renal Involvement and Childhood Henoch-Schönlein Purpura

Abbreviations: ACR, American College of severe bowel angina); arthritis/arthralgia; persistent purpura or relapse; WBC > 15 × 109/L;
Rheumatology; ASO, antistreptolysin O; C3, platelets > 500 × 109/L; elevated ASO; and low C3. Relevant clinical interventions for these
complement component 3; CRP, C-reactive
protein; ESR, erythrocyte sedimentation rate;
risk factors may exert positive effects on the prevention of kidney disease during the early
EULAR, European League Against Rheumatism; stages of HSP. However, the results should be interpreted cautiously due to the limitations
HSP, Henoch-Schönlein purpura; HSPN, Henoch- of the studies.
Schönlein purpura nephritis; OR, odds ratio; WBC,
white blood cell; WMD, weighted mean difference.

Introduction
Henoch-Schönlein purpura (HSP) is the most common small vessel vasculitis in childhood,
with an annual incidence of 10–20 per 100,000. More than 90% of patients are younger than
10 years old [1]. The clinical features of HSP have been well described and are predominantly
non-thrombocytopenic purpura, arthritis, abdominal pain, gastrointestinal bleeding, and
glomerulonephritis. Numerous investigations suggest that HSP is not a self-limited disease as
previously thought and may eventually develop into chronic kidney disease in childhood [2–
3]. Long-term prognosis depends mainly on the severity of renal involvement, which may
manifest as persistent hematuria, proteinuria, nephritic or nephrotic syndrome, or even renal
failure [4]. To prevent or delay end-stage renal disease, identification of early-stage nephritis is
crucial.
The risk factors associated with renal involvement in HSP are not well known although epi-
demiologic and clinical features and some abnormal laboratory findings have been suggested
to have a predictive role [5]. In this meta-analysis, we assessed the quality of available evidence
regarding risk factors that may predict renal involvement in childhood HSP, and present a
summary of our results.

Methods
Literature search strategy
The databases PubMed, Embase, and Web of Science were searched for papers published from
January 2000 to September 2016, using basic search terms from combined text and Medical
Subject Heading (MeSH) terms, including a MeSH search using ‘Purpura, Henoch-Schönlein’
and a keyword search using the word ‘Henoch-Schönlein purpura’, and terms related to risk
factors (including a MeSH search using ‘Risk Factors’, and a keyword search using the words
‘risk factors’). This search strategy was modified to fit each database. References from pub-
lished review articles were reviewed to identify additional relevant studies (S1 Text). Cohort
studies or case-control studies that evaluated the risk factors for developing HSP nephritis
(HSPN) were included. Titles and abstracts of articles found were screened, and articles of
interest were also selected for evaluation of the full article.

Study selection criteria

Patients were diagnosed with HSP at < 18 years of age, with consideration for the criteria of
the American College of Rheumatology (ACR) [6] and definitions of the European League
against Rheumatism (EULAR) [7], in which HSPN is defined as the presence of hematuria or
proteinuria at two different times within 6 months of HSP onset. Renal involvement was
defined as the presence of proteinuria, hematuria, or blood cell casts. The studies in our meta-
analysis must include detailed information after the onset of HSP and the length of follow-up

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 Renal Involvement and Childhood Henoch-Schönlein Purpura

time should be increased at least up to 6 months. Thrombocytopenia and systemic lupus ery-
thematosus at the onset were excluded.

Data collection and data extraction

Studies were selected by 2 independent reviewers according to the predetermined inclusion
criteria, and disagreements were resolved by a third reviewer. Case reports, genetic association
studies, review articles, comments, meeting abstracts, and editorial comments were excluded.
The extracted data included the studies’ characteristics (publication year), design features, par-
ticipants (e.g., setting, ethnicity, case number, age, male/female ratio, positive cases of HSP
and HSPN, factors (e.g., the laboratory predictors), and diagnostic criteria.

Bias and quality assessments of the included studies

The recommended checklist of the STROBE (Strengthening the Reporting of Observational
Studies in Epidemiology) initiative was used to assess the risk of bias of the included studies
[8]. A quality assessment of the studies was performed using Newcastle-Ottawa scale, NOS
(http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp), under three main catego-
ries: a selection of study; comparability of groups; and determination of outcomes [9].

Statistical analysis
We estimated the odds ratio (OR) with 95% confidence interval (CI) for dichotomous out-
comes. A random-effects model was used regardless of heterogeneity. Heterogeneity among
trials was tested using the I2 test and considered significant at I2 > 50% or P- value < 0.1. The
random effects model was used for the meta-analysis if there was significant heterogeneity.
Subgroup analyses were conducted regarding interval levels in the risk factors (e.g., gender),
quality of evidence, and diagnosed criteria. Sensitivity analyses were performed to evaluate the
effect of each study on the pooled ORs. The presence of publication bias was also evaluated
using the Begg’s and Egger’s test [10,11]. All statistical analyses were performed using Stata
12.0 software (Stata Corp, College Station, TX, (USA) [12].

Results
Study selection and characteristics
Initially, 386 potentially relevant studies were considered (Fig 1), but only 13 studies satisfied
the inclusion and exclusion criteria and were included in this meta-analysis (Table 1). These
studies were published between 2000 and 2016, and all of them are case-control studies. Two
were conducted in Turkey, four in China, and one each in Japan, Korea, Spain, Brazil, Finland,
Iran, and Thailand. Studies were performed in 2 major ethnic populations; 8 studies were con-
ducted in Asia (6 East Asian), while 5 studies were conducted with Caucasians. Five studies
used the criteria of the EULAR, and 8 used the criteria of the ACR. The 13 studies comprised
2398 children with HSP; 974 of these children had renal involvement.

Quality of evidence
NOS scale for case-control studies was applied to assess the quality of the evidence. Six studies
were judged to be of high relative quality [13–18] and 7 were of medium quality [19–25]. In
the selected studies, the controls were not community-based except for Jauhola [13] and Mar-
iac [14]. An additional unclear confounder was not controlled within comparability categories,
which may be a possible source of bias. In addition, all of the 7 medium-quality studies may
contain bias due to a relatively short-term follow-up. (Table 2)

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Fig 1. Flowchart of selection process for eligible studies (PRISMA 2009 flow diagram).
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 Renal Involvement and Childhood Henoch-Schönlein Purpura

Table 1. Basic characteristics of included studiesa

Year Setting Ethnicity HSPN/HSP Age HSPN/HSP, y Risk factors b Criterion
Shin [15] 2006 Korea Asian 78/128 8.2 ± 3.1/6.7 ± 2.6 1 2 3 4 5 6 7 8 9 10 11 12 14 17 ACR
Jauhola [13] 2015 Finland Caucasian 102/121 8.2 ± 3.8/6.2 ± 3.0 1 2 4 7 8 13 14 15 16 ACR
Zhao [19] 2015 China Asian 45/96 7.8 ± 2.6 1 2 3 4 7 10 11 12 13 17 EULAR
Elmas [16] 2014 Turkey Caucasian 28/79 8.7 ± 4.1/7.1 ± 3.0 1 2 7 9 10 11 13 14 16 EULAR
Mao [20] 2014 China Asian 267/268 7.5 ± 2.7/6.4 ± 2.5 1 2 7 9 10 11 14 16 EULAR
Anil [17] 2011 Turkey Caucasian 192/238 7.9 ± 2.8/7.5 ± 2.8 1 2 6 8 9 11 13 ACR
Zhu [21] 2014 China Asian 80/38 10.41 ± 2.70 1 2 7 8 9 14 15 17 ACR
Mariac [14] 2001 Spain Caucasian 8/61 6.9 ± 2.2/6.1 ± 3.3 1 2 5 6 7 8 9 13 14 ACR
Kawasaki [18] 2003 Japan Asian 15/69 9.6 ± 3.7/8.7 ± 3.1 1 4 7 14 16 17 ACR
Limpongsanurak [22] 2011 Thailand Asian 11/156 6.9 ± 2.6 5 7 12 ACR
Luiz [23] 2007 Brazil Caucasian 70/72 —— 1 2 3 4 5 6 7 14 ACR
Wang [24] 2016 China Asian 37/34 8.6 ± 2.1 1 2 7 11 14 EULAR
Nickavar [25] 2012 Iran Caucasian 41/64 7.3 ± 2.6/5.3 ± 2.7 257 EULAR
a
All studies were case-control studies
b
Risk factor key: 1, age; 2, gender; 3, persistent purpura; 4, abdominal pain; 5, severe bowel angina; 6, gastrointestinal bleeding; 7, arthritis/arthralgia; 8,
relapse; 9, leukocytosis; 10, thrombocytosis; 11, CRP; 12, ASO; 13, ESR; 14, IgA; 15, IgE; 16, IgG; 17, C3.

doi:10.1371/journal.pone.0167346.t001

The control group of each study was selected from the same population as the case group
and was confirmed without kidney damage after the follow-up period. Controls were selected
independently by exposure status and without special clinical features. Both groups completed
the follow-up time and had similar rates of non-response. To ensure an efficient and valid
study, selection and restrict enrollment for patients was conducted in each study. In addition,
a stratified analysis (e.g., gender, age, clinical manifestation) and logistic regression for multi-
variate analysis for confounding factors (except for Limpongsanurak [22] and Nickavar [25])
were conducted in all selected studies. All the analyzed risk factors were shown to be directly
linked with renal damage.

Table 2. Newcastle-Ottawa quality assessment scale (case-control) for studies included in this meta-analysis
1 2 3 4 5 6 7 8 9 10 11 12 13
Was the case definition a. Yes, with independent validation*; b. yes, e.g., record linkage or based on ● ● ● ● ● ● ● ● ● ● ● ● ●
adequate self-reports; c. no description
Representativeness of the a. Consecutive or obviously representative series of cases*; b. potential for ● ● ● ● ●
case selection biases or not stated
Selection of controls a. Community controls*; b. hospital controls; c. no description ● ●
Definition of controls a. No history of disease (endpoint*; b. no description of source ● ● ● ● ● ● ● ● ● ● ● ● ●
Comparability a. Study controls for_ _ _ _(selecting the most important factor)*; b. study ● ● ● ● ● ● ● ● ● ● ● ● ●
controls for any additional factor*
Ascertainment of exposure a. Secure record (e.g., surgical records)*; b. structured interview where blind ● ● ● ● ● ● ● ● ● ● ● ● ●
to case/control status interview not blinded to case/control status*; d. written
self-report or medical record only; e. no description
Ascertainment for cases & a. Yes* b. No ● ● ● ● ● ● ● ● ● ● ● ● ●
controls
Non-response rate a. Same rate for both groups*; b. non-respondents described; c. rate different ● ● ● ● ● ● ● ● ● ● ● ● ●
and no designation
Score 7 8 6 7 6 7 6 8 7 6 6 6 6

*Scored points

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 Renal Involvement and Childhood Henoch-Schönlein Purpura

Results of meta-analysis
We observed a consistent significant association between 12 risk factors and renal involvement
in childhood HSP: gender, age, abdominal pain, gastrointestinal bleeding, severe bowel angina,
persistent or relapse purpura, WBC > 15 × 109/L, platelet count > 500 × 109/L, elevated ASO,
and decreased complement component 3 (C3; Table 3 and Figs 2–5). In addition, there was no
association between girls with HSP and HSPN (OR 1.15; 95% CI [0.77–1.71]) where P = 0.12.
Arthritis/arthralgia may be a risk factor according to the criteria of the ACR in our analysis
(1.41, 1.01–1.96, Fig 6).

Subgroup and sensitivity analysis

Except for arthritis/arthralgia, the subgroup analysis showed no evidence of heterogeneity
between ACR and EULAR (Fig 6). The sensitivity analysis showed that no individual study sig-
nificantly altered the results, except for the medium-quality study of Zhao et al. [19], which
was the main origin of heterogeneity in abdominal pain (Fig 7). After the deletion of the study,
the heterogeneity vanished (Fig 8). A further analysis of studies of different quality revealed
that although studies of higher quality may have a more positive effect than medium-quality
studies, both had similar results (S2 Appendix). Therefore, the data of each study in the meta-
analysis was relatively stable and credible.

Publication bias
Assessment of publication bias using Egger’s and Begg’s tests showed that there was no poten-
tial publication bias among the included trials (e.g., gender; Egger’s test P = 0.46, Begg’s test,
P = 0.78; Fig 9).

Table 3. Results of meta-analysis by system

Possible risk factors Inconclusive Results
Age Older age WMD = 0.90,95% CI (0.61–1.19), P = 0.00
>10 year-old = 3.13,95% CI (1.39–7.07), P = 0.06
Boy OR = 1.36,95% CI (1.07–1.74), P = 0.02
Girl OR = 1.15,95% CI (0.77–1.71), P = 0.15
Digestive tract Abdominal pain OR = 1.94,95% CI (1.24–3.04), P = 0.04
Gastrointestinal bleeding OR = 1.86,95% CI (1.30–2.65), P = 0.70
Severe bowel angina OR = 3.38,95% CI (1.17–9.80), P = 0.02
Skeletal Arthritis/arthralgia OR = 1.41,95% CI (1.01–1.96), P = 0.60
Dermal Persistent purpura OR = 4.02,95% CI (1.22–13.25), P = 0.02
Relapse OR = 4.70,95% CI (2.42–9.14), P = 0.00
Blood pressure OR = 1.10,95% CI (0.63–1.92), P = 0.42
Orchitis OR = 0.94,95% CI (0.30–2.94), P = 0.33
Routine blood test WBC > 15 × 109/L OR = 2.42,95% CI (1.39–4.22), P = 0.00
PLT > 500 × 109/L OR = 2.98,95% CI (1.22–7.25), P = 0.02
Positive ASO OR = 2.17,95% CI (1.29–3.64), P = 0.00
Elevated ESR OR = 0.90,95% CI (0.65–1.23), P = 0.33
Elevated CRP OR = 1.33,95% CI (0.77–2.28), P = 0.06
Immunologic function Elevated IgA OR = 1.24,95% CI (0.65–2.37), P = 0.02
Elevated IgE OR = 1.06,95% CI (0.45–2.49), P = 0.19
Elevated IgG OR = 0.65,95% CI (0.22–1.90), P = 0.41
Decreased C3 OR = 3.13,95% CI (1.62–6.05), P = 0.91
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Fig 2. Forest plots of OR/WMD estimates for the following risk factors: (A) age; (B) gender: (C) older age
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Fig 3. Forest plots of OR estimates for the following risk factors: abdominal pain; gastrointestinal bleeding; severe bowel angina; arthritis or
arthralgia; blood pressure; orchitis; persistent purpura; relapse
doi:10.1371/journal.pone.0167346.g003

Discussion
The possible risk factors of renal involvement in childhood Henoch-Schönlein purpura have
been reported during past 15 years. Future studies should include a better definition of patients
at risk, and then treatment and clinical trials should be adapted to patients’ risk profiles [26].
The present study attempted to determine comprehensively the effect of a multitude of possi-
ble risk factors of renal involvement in childhood HSP. The risk factors included demographic
features; (age, gender), clinical features; (gastrointestinal tract, skeletal system, skin, testicles,
and blood pressure) and some abnormal laboratory findings (such as elevated ASO, elevated
ESR, elevated CRP, elevated IgA/IgE/IgG and decreased C3).
A previous meta-analysis was published by Mao et al. [27], which suggested that older age;
elevated blood pressure, C3, hemoglobin, and urea nitrogen; and decreased albumin were risk
factors for renal damage in HSP patients. In detail, the analysis included 8 studies (12 possible
risk factors) and comprised 1222 patients, most of which were experimental studies without
follow-up and focused only on laboratory findings in HSP patients. To acquire adequate and
reliable clinical literature, our meta-analysis adopted a strict search strategy and included 13
studies (additional 1176 patients and 20 possible risk factors) that concern not only abnormal
laboratory findings, but also focus on other vital risk factors (e.g., epidemiological features and
clinical manifestations) in children with HSP. Meanwhile, we further assessed heterogeneity
by performing subgroup or sensitivity analyses of stratified risk factors (e.g., gender), quality
of evidence, and diagnostic criteria of HSP which have a great bearing on the interpretation of
the results. In addition, publication bias and potential confounding factors among the included
trials were well analyzed in our meta-analysis.
The criteria of the ACR and EULAR were implemented to define HSP. Some studies have
adopted the former, while others have utilized the European; Except for arthritis/ arthralgia
sensitivity analyses have shown no evidence of heterogeneity observed between both. In fact,
all patients with HSP complained of purpura without thrombocytopenia [28]. But while palpa-
ble purpura was found in 100% of the cases according to the ACR criteria, the EULAR criteria
base a diagnosis of HSP on other symptoms [29].
The majority of patients were diagnosed between the ages of 2 and 10 years. Sano et al. [30]
concluded that age older than 4 years was an independent risk factor for renal involvement,
while according to Jauhola et al. [13] age over 8 years at onset was a risk factor for developing
nephritis. Our present meta-analysis showed that older children were at higher risk of renal
involvement than younger children. Furthermore, the subgroup analysis revealed that children
over 10 years old were more likely to suffer HSPN. Therefore, careful attention should be paid
especially to children older than 10 years at onset (Table 3 and Fig 2).
Our meta-analysis based on 10 studies showed that boys are at higher risk for renal involve-
ment than girls. This result is similar to a previous epidemiological survey based on 1.1 million
children younger than 17 years in West Midland which reported a boy-to-girl ratio of 1.2:1.0
[31].Male predominance has also been reported in other studies [16, 32, 33]. Male hormones
may have a pathogenic role in the course of HSP [34], but other studies reported that HSPN
was more common in girls [14, 23] (Table 3 and Fig 2).
Digestive tract symptoms (abdominal pain, gastrointestinal bleeding, and severe bowel
angina) and skeletal system symptoms (arthritis/arthralgia) are the predominant manifesta-
tions in HSP. The meta-analysis based on 4 studies showed that gastrointestinal bleeding also

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Fig 4. Forest plots of OR estimates for the following risk factors: ASO; CRP; ESR; leukocytosis; thrombocytosis
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Fig 5. Forest plots of OR estimates for the following risk factors: IgA; IgE; IgG; C3
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Fig 6. Result of sensitivity analysis and subgroup analysis on arthritis/ arthralgia.

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Fig 7. Result of sensitivity analysis on abdominal pain.

doi:10.1371/journal.pone.0167346.g007

increased the risk of renal involvement. Even so, few published articles have recognized gastro-
intestinal bleeding as a risk factor in HSP, and more cohort studies are necessary to identify
whether gastrointestinal bleeding is an independent risk factor of HSPN(Table 3 and Fig 3).

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Fig 8. Forest plots of OR estimates for abdominal pain after the deletion of an unstable study.
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Fig 9. Assessment of Publication bias using (A) Egger’s and (B) Begg’s test.
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Our review showed that digestive tract symptoms (abdominal pain, gastrointestinal bleed-
ing, and severe bowel angina) were strongly related to renal involvement. In a retrospective
study of 141 patients with HSP, Zhao et al. [19] showed that abdominal pain was not related to
HSPN. However, 45% of the patients were complicated with obesity and 29.8% of them had a
long disease course. This was a distinctly different epidemiological feature from other studies,
and the possibility of admission bias could explain the heterogeneity (Fig 7). Abdominal pain
and severe bowel angina are both unpleasant when patients suffer gastrointestinal involvement
in HSP. Our analysis suggested that the two levels of gastrointestinal reactions are essentially
equivalent for predicting renal injury in HSP. The mechanism probably is due to early sys-
temic corticosteroid administration for severe abdominal pain, which did not prevent severe
renal involvement [35]. As gastrointestinal symptoms are easily missed in clinical practice,
more attention should be paid to these patients (Table 3 and Fig 3).
The sensitivity analysis showed a completely different result regarding arthritis/arthralgia
between the criteria of the ACR and EULAR and the difference between two criteria may help
to explain. For skeletal system symptoms (arthritis/arthralgia), a relatively independent type of
HSP according to the criteria of the EULAR, patients with arthritis/arthralgia onset were
assigned equally to the HSP or HSPN group. This distribution to compare these groups would
not be possible if the criteria of the ACR were adopted (Table 3 and Fig 3).
Most identified studies showed an important association between abnormal skin manifesta-
tions (persistent purpura or relapse) and HSPN [36]. According to our meta-analysis, the risk
of renal damage in HSP children with persistent purpura is 1.22–13.25-fold that of patients
without persistent purpura, and the incidence of purpura relapse with renal involvement is
2.7-11-fold that of those who had no relapse. The study of Rigante et al. [37] showed that only
persistent purpura for more than one month was a risk of renal involvement in HSPN. The
mechanism probably is due to persistent small vascular inflammation and immune complex
deposition, which triggers a series of inflammatory reactions that may damage kidney tissues
(Table 3 and Fig 3).
Our analysis showed that WBC >15 × 109/L and platelet count >500 × 109/L were highly
correlated with renal involvement in HSP, and a WBC of 10 × 109/L to 15 × 109/L has no statis-
tical link to renal involvement. The mechanism may be a tissue injury induced by inflamma-
tory agents secreted by neutrophils triggered by an inflammation-induced factor [37]. Anti-
neutrophil cytoplasmic antibody was found to predict renal damage induced by HSP [38].
Thrombocytosis may be an early and useful indicator, and early studies have suggested that
reducing the platelet count may be an effective method to avoid renal involvement [39, 40].
However, a systematic review and meta-analysis of 13 randomized controlled trials performed
by Hahn et al. [41] revealed that there is no benefit in giving antiplatelet agents, such as dipyri-
damole and aspirin, to prevent kidney disease. Heparin may be effective but it is potentially
dangerous and should be taken cautiously. Additionally, there are no evidence that prednisone
is of benefit in preventing renal damage in HSP according to Hahn et al. [41] and Chartapisak
et al. [42] (Table 3 and Fig 4).
ASO is an antibody specific to streptolysin, which indicates streptococcal infections. Most
patients also had a history of upper respiratory tract infection [43] and a large proportion was
infected with streptococci. Our analysis suggested that upper respiratory tract infection, espe-
cially streptococcal infection related to high ASO, precedes HSPN [44]. So far, the mechanism
underlying an association between elevated upper respiratory tract infection with streptococ-
cus and kidney damage in HSP is unknown. According to the analysis, elevated ESR and CRP
are not related to HSPN (Table 3 and Fig 4).
From the reviewed literature, some patients with HSPN had low C3 (10%-20%), elevated
IgA (20%-50%), or both [31]. Our analysis also revealed that low C3 is an independent risk

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 Renal Involvement and Childhood Henoch-Schönlein Purpura

factor in HSP, which is a feature of post-streptococcal glomerulonephritis. Fretzayas et al. [45]

reported elevated IgA in 73% of all patients with HSP and in 95% of patients with HSPN, but
latter studies did not confirm elevated IgA as a risk factor associated with HSPN. In our pres-
ent analysis, elevated IgG and IgE may have no connection with HSPN. There were only two
papers that reported a link between serum IgG and IgE and HSPN, but the data for our analy-
sis was not sufficient to calculate the OR and obtain a reliable result (Table 3 and Fig 5).
Although some studies have claimed that high blood pressure and orchitis could be risk fac-
tors in HSP children, our meta-analysis showed that blood pressure and orchitis did not pre-
dict the occurrence of renal involvement (Table 3 and Fig 3).
In the meta-analysis, neither renal failure nor end stage renal disease were detected or
described in the selected studies. HSP is more common among children than adults, but there
are more end-stage renal disease events in adults [46]. However, management of HSP is diffi-
cult for pediatricians because of insufficient clinical data in adult stage. Previous studies
reported that severity and persistence of proteinuria were predictive of eventual renal failure
[47,48] while Butani [49] and Sanders and Wyatt [50]suggested that there are no clinical fea-
tures or prognostic markers to reliably identify children at highest risk for disease progression.
Limited numbers of patients and appropriate studies at presentation increase the difficulty in
performing a meta-analysis of a link between HSPN and end stage renal disease. Therefore, a
long-term follow-up should be conducted for children with HSPN to determine prognosis
when there is renal involvement.
Early identification of the risk factors of renal involvement in HSP has important implica-
tions for intervention and management. A sensitive scoring system based on these risk factors
at onset to predict HSPN may become a focus of research. For children with gastrointestinal
tract symptoms at onset, early gastrointestinal endoscopy is a good tool for assisting diagnosis
of HSP [51]. Children with more than one risk factor require more intervention than those
who are without those risk factors. The effectiveness of relevant preventive actions has been
confirmed: A clinical trial reported that leukocytapheresis could not only ameliorate gastroin-
testinal symptoms, but also prevent HSPN, persistent purpura, and relapse in HSP. For persis-
tent purpura and relapse, cyproheptadine could help prevent or at least decrease the
occurrence of HSPN in children [52].
Some shortcomings of the present meta-analysis should be considered. Firstly, our analysis
was based only on case-control studies, and the above risk factors cannot be relied on as causal
factors of renal involvement in HSP. The risk factors of renal injury in HSP remain unclear.
Case reports that point to new risk factors are increasing every year, and these may be a source
of confounding factors in the included studies. Secondly, measurements and missing data
were not described in detail in most of the included studies, which may indicate a possible
bias. Thirdly, grey literature was not considered, and only 2 major ethnic populations was
included, which may result in reporting and ethnicity selection bias. Fourthly, although there
is no statistical or clinical heterogeneity across the case-control studies, potential bias still exists
because of the 2 HSP diagnostic systems. For atypical HSP children, we should take a cautious
attitude towards the above risk factors. Finally, for several risk factors (e.g., age,leukocytosis,
thrombocytosis, and elevated ASO), relevant literature is limited and verification from clinical
data is required.

Conclusions
In conclusion, our study highlights the following as factors associated with renal involvement
in pediatric HSP: male gender, age > 10 years, severe gastrointestinal symptoms (including
abdominal pain, gastrointestinal bleeding, and severe bowel angina), arthritis/arthralgia,

PLOS ONE | DOI:10.1371/journal.pone.0167346 November 30, 2016 17 / 21

 Renal Involvement and Childhood Henoch-Schönlein Purpura

persistent purpura or relapse, WBC > 15 × 109/L, platelets > 500 × 109/L, elevated ASO, and
decreased C3. More attention should be paid to those children who have one or more of the
above risk factors, and a sensitive scoring system based on these risk factors at onset may help
predict renal injury in HSP patients. Relevant clinical intervention may exert positive effects
on the prevention of kidney disease in the early stage of HSP. Well-designed and convention-
ally reported studies with a considerable number of children with HSP are necessary to deter-
mine the possible link between these 13 risk factors and HSPN.

Supporting Information
S1 Appendix. PRISMA 2009 Checklist (DOC)
(DOC)
S2 Appendix. Subgroup analysis for quality of evidence: (A) age; (B) male gender; (C) older
age; (D) abdominal pain; (E) gastrointestinal bleeding; (F) severe bowel angina; (G) arthritis/
arthralgia; (H) persistent purpura; (I) relapse; (J) leukocytosis; (K) thrombocytosis; (L) ASO;
(M) C3
(ZIP)
S1 Text. Search strategy for each database
(DOC)

Acknowledgments
We are grateful to Dr. Daoqi Wu and Dr. Shaojun Li for the technical assistance.

Author Contributions
Conceptualization: QL HC.
Data curation: HC.
Formal analysis: HC YLT XHL.
Funding acquisition: QL HPY.
Investigation: YLT XHL.
Methodology: QL HPY HC.
Project administration: QL HC.
Resources: QL HPY MW.
Software: HC GFZ.
Supervision: QL HPY.
Validation: HC YLT.
Visualization: YLT.
Writing – original draft: HC HPY.
Writing – review & editing: HC HPY QL.

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 Renal Involvement and Childhood Henoch-Schönlein Purpura

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