Patient characteristics associated with participation in a practice-based study of depression in late life: The spectrum study

Objective: An important component of generalizing study results to patients is the extent to which study participants adequately represent individuals targeted for the study. The Spectrum study of depression in older primary care patients was utilized to consider patient characteristics associated with nonparticipation. Method: Interviewers utilized a validated questionnaire to screen adults aged 65 years and older for depression who presented to one of the participating primary care practices in the Baltimore, Maryland area. Screening interviews included information about sociodemographic factors, functioning, health, and attitudes about depression and its treatment in order to compare participants with persons who declined. Results: In all, 2,560 adults aged 65 years and older were screened. Comparison of the characteristics of the patients who were eligible for the study (n = 773) with patients who participated fully in the in-home evaluation (n = 355) found that the study sample included proportionately more persons who: 1) were less than 80 years old; 2) completed high school; and 3) reported two or more visits to the practice site within six months of the interview. Among patients who were depressed, no significant differences were found in the characteristics of those who met study eligibility criteria and those who agreed to participate. Conclusions: Persons over the age of 80 years of age or those with less than a high school education may require tailored strategies for recruitment even when approached by a trained interviewer in a primary care doctor's office.