Compliance with sulfonylureas in a health maintenance organization: a pharmacy record-based study

OBJECTIVE: To determine which factors affect compliance with sulfonylureas in a population served by a health maintenance organization in Southern California. METHODS: Retrospective analysis of pharmacy records and healthcare utilization data for two years (April 1993-March 1995), and a survey mailed to patients. Patients treated with sulfonylureas were selected for analysis on the basis of their prescription profile. Compliance was measured from the pharmacy records as the proportion of days the patient was in possession of the prescribed medications. Patient compliance with sulfonylureas was modeled as a function of four clusters of determinants: patient-related attributes, drug regimen characteristics and complexity, health status and disease-related variables, and characteristics of the interaction with healthcare providers. RESULTS: 786 patients were identified for analysis (49.1% women, mean age 59 y). The mean compliance rate was 83% +/- 22% SD. Compliance was significantly positively related with age and self-reported level of medication-taking compliance at baseline. Factors shown to have an inverse relationship with compliance were treatment complexity, perception of general health, and being a newly treated patient (adjusted R2 for the final model = 0.148). CONCLUSIONS: Our results suggest that factors found to be associated with noncompliant behavior (e.g., being a newly treated patient, self-reported compliance, regimen complexity) can be assessed by physicians and pharmacists as a routine practice.