Growth patterns in juvenile rheumatoid arthritis.

Objective: To define patterns of growth in juvenile rheumatoid arthritis (JRA) and to evaluate possible associated clinical and laboratory correlates.
Methods: The study population comprised 67 children with JRA who had been followed for 5 years or longer and whose follow-up period did not extend beyond 18 years of age. Height and weight z scores were calculated with reference to age-related standards for each of the annual follow-up intervals and correlated with JRA subtype, the presence of rheumatoid factor (RF), the erythrocyte sedimentation rate (ESR), alkaline phosphatase level (ALP) and medication history.
Results: Initial height-for-age (HAZ) scores for pauciarticular, polyarticular and systemic JRA onset groups (PaJRA, PoJRA and SJRA respectively) were +0.27, -0.07 and +0.40 respectively. A significantly lower HAZ score in the SJRA population compared to the PaJIA population first became apparent at year 2 and the difference was maintained throughout the 9-year follow-up period. A significantly lower HAZ score in the SJRA population compared to the PoJRA population first became apparent at year 6 and the difference was maintained until the ninth year. During the 9-year follow-up period, RF-positive children tended to have negative HAZ scores whereas RF-negative children tended to have positive HAZ scores. The SJRA onset group displayed significantly lower HAZ scores, as compared to the HAZ score at onset, for 7 of the 9 subsequent follow-up intervals. Only 2 patients had heights < 2SD below the mean at final determination. Delay in generalized linear growth occurred predominantly in the SJRA population and to a lesser degree in those with PoJRA associated with RF positivity.
Conclusions: Delay in linear growth occurs in some children with JRA. Patients with pauciarticular and RF-negative polyarticular disease can have growth patterns similar to normal children. Children with RF-positive polyarticular and systemic JRA have more significant growth retardation that occasionally can be sustained and extreme.