To identify risk factors for early study termination and motivators for adherence to a long-term followup trial and to improve completeness of long-term studies.
Risk factors for early termination in 508 included patients were identified through Cox regression analysis. Patients completing the 10-year followup filled in a questionnaire on possible motives for continued study participation.
Risk factors for early termination were higher age (hazard ratio [HR] 1.03, 95% confidence interval [95% CI] 1.02-1.04), functional disability during the preceding year (HR 1.54, 95% CI 1.20-1.99), having achieved drug-free remission (HR 6.62, 95% CI 2.07-21.14), limited joint damage (HR 0.98, 95% CI 0.97-0.995 for actual damage; HR 0.83, 95% CI 0.73-0.94 for damage progression), and few adverse events (HR 0.35, 95% CI 0.26-0.47). A total of 288 of 313 patients (92%) attending the last visit answered the questionnaire. The majority mentioned contributing to scientific research (97% agreed), helping other patients (91%), and learning about new treatment strategies (84%) and their disease (85%) as reasons to continue participation. Next, patients mentioned tight control (202 of 278 patients), good treatment strategy (128 of 278), good medication (117 of 278), and good half-term results (102 of 278) as motivators. More than 95% of patients experienced participation "as expected" or "better than expected." Additional examinations during yearly visits (extra questionnaires, imaging) were mentioned as "worse than expected" (10%), as was answering routine questionnaires (7%).
Continued participation was relatively high in the Treatment Strategies for Rheumatoid Arthritis (BeSt) Study. Higher age, functional disability, drug-free remission, little joint damage, and few adverse events predicted early study termination. Main motives for continued participation were a willingness to contribute to research, help future patients, and because patients had good experiences with the study protocol.