Factors associated with attrition in a longitudinal rheumatoid arthritis registry

Loss of participants in longitudinal data collection can affect the validity of outcomes in rheumatoid arthritis (RA) registries. Prior research indicates that demographics and socioeconomic and psychosocial factors contribute to attrition. This study analyzed the characteristics of an RA registry that may contribute to attrition in a hospital-based population.

Subjects consisted of RA patients enrolled in the Brigham and Women's Rheumatoid Arthritis Sequential Study. Demographics and clinical and psychological factors were evaluated in univariate analyses to determine differences between participants who dropped out and those who completed 5 years of followup. Univariate factors with a P value <0.1 were used in a survival analysis to determine significant factors associated with attrition. A secondary analysis looked at patients who dropped out during the first year.

A total of 1,144 RA participants were enrolled (509 completed 5 years of followup, 227 were still actively enrolled, and 408 dropped out). The attrition rate was 4.31% per 6-month cycle. Shorter disease duration, higher disease activity (3-variable Disease Activity Score in 28 joints using the C-reactive protein level), less education, RA drug therapy, and lower arthritis self-efficacy were statistically significant in multivariate survival analyses. In a secondary analysis, sex and age were the only additional factors found that contributed to attrition.

The attrition rate for this registry was similar to rates reported by other registries. Shorter disease duration, higher disease activity, and several other socioeconomic factors were associated. Men and younger patients tended to drop out during the first year. Population differences in each registry may result in different attrition patterns and ultimately, each longitudinal registry should consider conducting its own analyses.