Several studies relate growth retardation and JIA but longitudinal comparative anthropometric data in different subsets of JIA population in a developing country are scarce. The objective of the present study was to evaluate the growth pattern in patients with JIA and its different subtypes in comparison to age, sex and temporally matched controls.

This prospective study was carried out at pediatric rheumatology clinic of Institute of Post Graduate Medical Education and Research (IPGMER), Kolkata from January 2009 to December 2011. Ethical clearance was taken from the institutional ethics committee. A written consent was taken from the parents of all the participants.

Children between the ages of 2 and 12 years with symptoms of JIA, evaluated and diagnosed by International League of Associations for Rheumatology (ILAR) criteria [8] were included as study population. The categorization and the subtyping were also done as per ILAR guidelines. Children with similar age and sex attending the outpatient department at the same time for upper respiratory tract infections were taken as temporally matched controls. Children with chronic co-morbid endocrinal, renal, hematological or other diseases which cause growth retardation were not included in the study.

Children with JIA and control children were measured for body weight and standing height using the same equipment and the same observer. The weight was measured by digital weighing machine (Nova, India), with minimum clothing, to the nearest of 0.1 kg. Height was measured by a stadiometer (Hardik medi-tech, India) to the nearest 0.1 cm. The weight and height were recorded in triplicate and the average values were analyzed. Anthropometry was repeated at six-monthly intervals in both the cases and controls. Growth velocity (cm/y) was measured from the differential values of linear growth divided by the time under evaluation. The patients who missed the date were contacted over telephone to ensure attendance within 7 days. Those who did not return after two intimations were considered drop-outs and not included in the analysis.

Statistical Analysis: Descriptive analyses were done for most variables. Numerical variables were compared between JIA patients and controls by Student’s unpaired t test when normally distributed, and by Mann Whitney U test when skewed. Multiple group analysis was done by One way analysis of variance (ANOVA) and Tukey’s test as post hoc test for comparison between two individual subgroups. Chi-square test was used to compare categorical variables between groups. All analyses were 2 tailed and P<0.05 was considered statistically significant. Analysis were done using Statistica version 6 (Tulsa, Oklahoma: StatSoft Inc, 2001) and SPSS version 17 (Illinois, Chicago; SPSS Inc, 2008).

Out of 87 patients of JIA presenting during study period, 75 completed the study; 37 (49%) had oligoarthritis, 26 (35%) had polyarthritis [Rheumatoid factor (RF) negative 20 (27%), RF positive 6 (8%)], systemic JIA 11 (15%), and enthesitis related arthritis (ERA) 1(1.3%). The mean (SD) age of the study population (41 males and 34 females) was 8.48 (3.0) years. The mean (SD) age of onset of symptoms was 7.01 (3) years. The mean (SD) age of onset in different subtypes were 5.15 (3.0) years, 7.09 (3.0) years and 7.95 (3.0) years in systemic JIA, oligoarthritis and polyarthritis, respectively.

TABLE I   Anthropometric Data of JIA Patients (N=75) and Control (N=75) at the End of the Study

Anthropometry of JIA patients and controls are compared in Table I. Comparison between the different subtypes showed statistically significant difference in terms of height, weight and growth velocity but not in body mass index (BMI) (Table II). Height and weight were more restricted in patients with systemic JIA; growth velocity was lowest in RF positive polyarthritis.

TABLE II  Comparison Between Different Sub-types of JIA Patients and Matched Controls

Multiple comparison analysis by Tukey’s test showed significant difference in systemic JIA patients with respect to height (P=0.018; 95% CI 2.13-33.77) and weight (P=0.008; 95% CI 1.47-14.43) when compared with controls. Growth velocity was significantly affected in RF positive polyarthritis (P=0.003; 95% CI 0.46-3.14). Comparison between oligoarthritis and seronegetive polyarthritis did not reveal any significant difference in anthropometry (Table III).

TABLE III Summary of Statistical Significance (P value)  of Comparison Between Subtypes and Control

In the present prospective study, the JIA patients had lower (but statistically insignificant) weight, height, BMI and growth velocity as compared to age- and sex-matched controls. The patients with systemic JIA had signifiant impairment of weight and height whereas growth velocity was significantly lower in polyarticular RF positive subjects.

Limitations of the present study include small and unequal sample size in various subtypes of JIA. Moreover, the controls were not selected separately for each subtype as disease categorization was not complete at the time of entry of patients into the study. The degree of growth retardation or the etiology and influencing factors in each subject or category were not evaluated in the present study. The peak height velocity of adolescents was also not evaluated.

JIA, a chronic inflammatory disease, is frequently associated with growth retardation. [1-3,9,10]. The overall degree of such retardation is variable depending upon the study population, method of study, etiologic factors and disease subtypes. In a retrospective review by Padeh, et al. [2], growth retardation was found in 35.8% of patients while another study [11] demonstrated short stature in only 4.3%. Significant retardation of growth was not demonstrated in JIA in the present study, which is consistent with an earlier report from United Kingdom [12]. The subtype-specific growth impairment, which showed systemic JIA and polyarthritis groups being most affected is also reported by other researchers [13-15]. A long-term study over 5 years by Okumus, et al. [16] found statistically significant difference in height standard deviation score in polyarticular and systemic JIA. Data from developing countries are still scarce. One recent study from India demonstrated a significant growth impairment in adolescent boys, with delay in peak height velocity [18]. Most affected subjects had polyarthritis and systemic JIA. They found 66% patients with JIA from Kolkata to be below the 3rd percentile of height when compared with CDC 2000 standards [18].

Meticulous evaluation of physical development and simultaneous monitoring of disease activity are essential components in the management of JIA. Growth monitoring in terms of weight, height, BMI essential for early detection of growth faltering.

We conclude that significant growth retardation occurs in systemic JIA and RF positive polyarthritis.

Contributors: RM, SS, NKD, SC, AD, BR, SG, MN: diagnosis and management of the patients; RM, NKD, SS, AH and TKS: drafted the manuscript; SS: critical review. All authors approved the final version; RM and SS shall act as guarantors.

Funding: None; Competing interests: None stated.

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