Distance from Home to Research Center: A Barrier to In-Person Visits but Not Treatment Adherence in a Stroke Trial

Background and Purpose: Clinical trials often seek to enroll patients from both urban and rural areas to safeguard the generalizability of results. However, maintaining contact with patients who live away from a recruitment site, including rural areas, can be challenging. In this research we examine the effect of distance between patient and study centers on treatment adherence and retention. Methods: Secondary analysis of 2,466 participants in the Insulin Resistance Intervention after Stroke trial who were enrolled from research sites in the United States. Driving distance between the zip-codes of patient's reported place of residence and the study center was calculated. Outcome measures were loss to follow-up, completion of annual in-person visits, adherence to preventive therapy, and adherence to study drug in the first 3 years of participation. Logistic regression models were used to adjust for confounders. Results: Distance from residence to research center was not associated with loss to follow-up, adherence to study drug, or adherence to preventive therapy (p > 0.05 for each). However, patients who lived farther from the research center (>120 miles), compared to patients who lived closer (<60 miles), were less likely to complete the second annual in-person visit (62 vs. 81%; adjusted OR 0.48; 95% CI 0.31-0.75) and third visit (53 vs. 75%; adjusted OR 0.44; 95% CI 0.29-0.67). Conclusions: Distance between patient and study center was an independent predictor of missed in-person visits but not with adherence to study treatment or preventive care. (C) 2018 S. Karger AG, Basel