Development and validation of a survey to assess barriers to drug use in patients with chronic heart failure.

Scot H. Simpson, Pharm.D., M.Sc., Jeffrey A. Johnson, Ph.D., Karen B. Farris, Ph.D., and Ross T. Tsuyuki, Pharm.D., M.Sc. Objective. To report the development of and initial experience with a survey designed to assess patient-perceived barriers to drug use in ambulatory patients with heart failure. Methods. The Barriers to Medication Use (BMU) survey, developed from previous qualitative work by our group, was administered to 128 consecutive patients attending an outpatient heart failure clinic. The first 42 patients to return the survey were mailed a second survey to evaluate response stability over time. The survey contained 31 questions in five barrier domains (knowledge, previous drug therapy experiences, social support, communication, and relationship with health care professionals). Patients also completed the Minnesota Living with Heart Failure (MLHF) questionnaire and a self-reported drug use scale. Frequency of drug refills was used to estimate adherence. Reliability and construct validity of the BMU survey were assessed using correlation coefficients. Results. Response rates were 89% and 93% for the first and retest surveys, respectively The BMU survey showed modest internal consistency in the overall survey and in two of the five barrier domains. Responses to the first and retest surveys showed good stability over time in the overall survey and in four of the five barrier domains. Patients with good adherence reported few barriers; however, the association was not strong (Pearson correlation coefficient r = -0.14, p=0.14). Patients who reported few barriers also reported better MLHF scores (r = 0.42, p < 0.001), with the strongest association in the social support domain (r = 0.53; p < 0.001). All respondents reported having a good relationship with health care professionals. The most common barriers to drug use were poor support networks and previous adverse reactions. Conclusion. The BMU survey demonstrated reasonable reliability and validity characteristics in this first clinical experience. Despite high adherence, patients still reported barriers that may hinder optimal drug use.