Osteopenia in adults with a history of juvenile rheumatoid arthritis. A population based study.

OBJECTIVE: To determine the extent of osteopenia in a population based cohort of adults with a history of juvenile rheumatoid arthritis (JRA).

METHODS: The Rochester Epidemiology Project database was used to identify all cases of JRA diagnosed among Rochester, Minnesota residents under the age of 16 years between January 1, 1960, and December 31, 1993. Thirty-two of the 57 adult patients in this population based cohort (ages 19-53 years, mean 35) participated in this study. Average length of followup from the time of diagnosis was 27.1 years (median 26.9, range 7.7-39.1). Dual energy x-ray absorptiometry scans were used to assess bone density of the lumbar spine, hip, distal one-third radius, and whole body. In addition, a number of variables that influence bone mass were analyzed.

RESULTS: Although many participants had T scores within the normal range (T score > -1) at all measured sites, 41% (n = 13) were osteopenic (T score < or = -1) at either the lumbar spine or femoral neck. Twenty-eight percent (n = 9) had T scores < or = -1 in the lumbar spine (p = 0.058 relative to expected). Thirty-two percent (n = 10) had T scores < or = -1 in the femoral neck (p = 0.012 relative to expected). Several variables were significantly (p < 0.05) associated with low bone density in this cohort of adults with a history of JRA, including: (1) revised Steinbrocker functional class > or = 2 during adolescence, indicating poorer physical functioning; (2) lack of participation in organized sports during adolescence (a surrogate measure of physical activity); (3) tobacco use during adolescence; and (4) lower calcium intake during adolescence.

CONCLUSION: Although many adults with a history of JRA have normal bone density, a substantial subset are osteopenic, placing them at increased risk of fractures later in life. This observation is particularly striking given the predominance of patients with pauciarticular JRA in this population based group. We identified several variables associated with osteopenia in this cohort. Further work is needed to identify those patients with JRA who may benefit from aggressive therapy targeted at preventing the longterm morbidity associated with osteopenia.