To assess bone mineral density (BMD) and bone turnover in adults with a history of juvenile chronic arthritis (JCA) or persistent JCA, and to identify predictors of reduced BMD.
Sixty-five white patients (mean age 32.2 years) with a history of JCA and 65 age-, sex-, height-, and weight-matched healthy control subjects participated in the study. Densitometry of the left hip and the lumbar spine was performed, and osteocalcin (bone formation marker) and crosslinks (bone resorption marker) were measured. In addition, bone-related clinical parameters were assessed in the JCA group.
BMD in the hip and lumbar spine was significantly lower in the JCA group than in the controls. Levels of osteocalcin and crosslinks were significantly increased in the JCA group. According to WHO definitions, significantly more subjects in the JCA group had "osteopenia" and "osteoporosis" than would be expected in a normal population sample. Active disease at the time of the study (1996-1997), baseline erosions evaluated in 1979, Steinbrocker functional class in 1996-1997, polyarticular course of JCA, and history of systemic steroid treatment for more than 1 year were significantly associated with reduced BMD. In linear regression analysis including both the JCA and control groups, presence of JCA proved to be the factor most strongly associated with reduced BMD, explaining approximately 20% of its variation.
Reduced BMD and evidence of increased bone turnover suggest that JCA patients may be at risk of developing premature osteoporosis and associated fractures later in life. The data are consistent with the concept that BMD in JCA is determined by many factors.