Effect of patient comorbidities on filling of antihypertensive prescriptions

Objectives: To evaluate the extent of patient failure to fill antihypertensive prescriptions and to test the hypothesis that the presence of non-cardiovascular disease is negatively associated with filling an antihypertensive prescription, and, conversely, that the presence of cardiovascular disease is positively associated with filling an antihypertensive prescription. Study Design: Cross-sectional. Methods: We sampled prescriptions written for 327 African Americans aged ≥18 years. Patients were enrolled in a Medicaid managed care plan and treated in 6 primary care practices between January 1, 2003, and February 8, 2005. Prescription filling was defined as a match between a new or renewed electronic prescription and an insurance claim within the next 30 days. We assessed the association of comorbidity type with filling an antihypertensive prescription by using an adjusted logistic regression model that accounted for clustering of prescriptions within patients. Results: Of 1742 antihypertensive prescriptions, 1309 (75.1%) were filled. Prescriptions written for persons with 5 or more noncardiovascular comorbidities were significantly more likely to be filled (adjusted odds ratio [OR], 1.59; 95% confidence interval [CI], 1.07 ± 2.36) versus those for persons with fewer noncardiovascular comorbidities. The presence of cardiovascular comorbidities was not associated with filling of an antihypertensive prescription (adjusted OR, 0.72; 95% CI, 0.45-1.14). Conclusion: Many antihypertensive prescriptions were not filled. Different types of patient comorbidity may differentially impact prescription filling. Further studies should examine whether these results generalize to other populations.