Are Indian patients with juvenile-onset ankylosing spondylitis taller than reference population?

BACKGROUND & OBJECTIVES Paucity of growth retardation has been observed by us in patients with juvenile-onset ankylosing spondylitis (JAS) in a tertiary care health centre in south India. We, therefore, undertook this pilot study to assess and compare anthropometry of patients with JAS who were 15 yr and older with that of adult onset ankylosing spondylitis (AAS) and matching Indian reference population. METHODS Consecutive male patients (December 2009- October 2012) with JAS and AAS fulfilling Modified New York Criteria were selected after applying inclusion and exclusion criteria. Demography and anthropometry were noted. Height of both patient groups as well as their parents and siblings were compared with that of the reference population. Mid-parental height and delta height were derived. Those with delta height of >8.5 cm were compared with the remaining. Multivariate logistic regression was done for variables that were found to be significant by chi-square in bivariate analysis. Similar analysis was done for BMI also. RESULTS There was no significant difference in anthropometric variables between JAS and AAS groups. Twenty eight of the 30 (93.33%) JAS patients were taller as compared to the reference population. Twenty six (86.67%) AAS patients were taller than the reference population. The mean heights of JAS (170.67 ± 6.94 cm) and AAS (168.2 ± 5.94 cm) patients were significantly higher than the reference value of 163.11 cm; both p0 <0.001. Logistic regression revealed that tallness in JAS was associated positively with hypermobility (OR=23.46,95%CI 1.2-447.2, p0 =0.036). No significant association was detected for height in AAS and for BMI in both JAS and AAS groups. INTERPRETATION & CONCLUSIONS No growth retardation was seen in patients with JAS in our study. Majority of patients with JAS and AAS were taller than reference population. The difference between mean height of JAS and AAS was not significant. Larger studies involving different populations are required to confirm these findings.