Determinants of non-compliance and attrition in the elderly.

BACKGROUND This report identifies demographic and health-related baseline factors associated with non-compliance and attrition in elderly subjects participating in a preventive intervention study over a 4-year follow-up period. METHODS The Cox proportional hazards model and polychotomous logistic regression were used to evaluate time to clinic assessment non-compliance and type of non-participation. RESULTS Of 1785 subjects, 35.6 percent were non-compliant during follow-up which meant they were eligible to participate at the time they were contacted but would not or could not return for an assessment. Refusals due to a lack of continuing interest or being too busy,and those citing health problems constituted the major subgroups of non-compliers. Death, unable to contact, and ineligible due to disenrollment or moving away accounted for nearly 20 percent. Four-year compliance was achieved by 44.4 percent of the participants. Time to non-compliance was significantly shorter with older age, lower annual income, poorer personal health ranking, and, to a marginal extent, depression. Lower annual income was associated with all reasons for non-participation including disenrollment or moving. Other factors correlated with specific types of nonparticipation. CONCLUSIONS These results can be useful in designing more effective cohort maintenance strategies. Greater resources may be allocated to subgroups who are less likely to continue.