Characteristics of rheumatoid arthritis patients: who participates in long-term research and who drops out?

A 10-year study of rheumatoid arthritis (RA) patients was conducted to identify characteristics associated with continued participation in a long-term research project.

Nine hundred eighty-eight RA patients were recruited from 56 private rheumatology practices. Over the course of the study, 45 patients died and were eliminated from the analysis. Patients were interviewed by phone each year for 10 years, and their physicians provided clinical data. Variables measured included demographic characteristics, perceived health status, employment status, family responsibilities, social support, and clinical health status.

Forty-six percent of patients remained in the study after 10 years. Survival analysis using Cox regression techniques assessed baseline factors that significantly predicted characteristics of patients who remained in the study. The multivariate analysis found that more educated patients, female patients, those with moderate to high levels of social support, patients having fewer joint groups with flares, and employed patients were more likely to remain in the study. Disease characteristics of stage of disease, level of pain, self-reported level of physical disability, and duration of RA were not significantly associated with continued study participation.

The results suggest that psychosocial and socioeconomic factors are more important determinants of continued participation in long-term research studies than are most clinical disease characteristics. Among clinical variables, only the active disease characteristic of joint flares predicted continued study participation. Overall disease characteristics such as disease stage or duration did not predict subject attrition.