Patient retention in a clinical trial: a lesson from the rofecoxib (VIOXX) study.

A high retention rate of patients and control subjects is an important criterion for the credibility and accuracy of prospective, randomized, controlled clinical trials. Retention and adherence depend on a combination of patient-, physician- and coordinator-related factors, and these need to be carefully evaluated to ensure success. The aim of the study was to evaluate predictive factors for patient retention in a clinical trial. Questionnaires containing items on demographic and clinical data and specific questions related to patient motivation were distributed to 31 patients participating in a clinical study comparing rofecoxib (Vioxx) and placebo for the prevention of colonic polyp recurrence. Adherence of the group with the rofecoxib study and the questionnaire was 100%. The sample included 24 men (77%) and 7 women of mean age 66+/-9 years; 90% were married, 42% were employed. A family history of colorectal cancer (CRC) was reported by 29%. The main reasons for adherence reported by the patients (on an analog scale of 0-10) were 24-hour availability of a nurse (9.2+/-1.9), the chance to prevent CRC (9.1+/-1.9), and participation in a multicenter study (9.1+/-2.2). The least important factor was support of the family physician (5.8+/-4.1). In conclusion, retention in a clinical trial mainly depends on the subject of the trial and the scientific/professional setting where it takes place, and less on the support of the family physician.