Factors Associated With Compliance, Discontinuation and Switching of Calcium Channel Blockers in 20,156 Chinese Patients

Abstract

Noncompliance and nonpersistence to antihypertensive drugs is a recognized worldwide problem. Calcium channel blockers (CCBs) are commonly prescribed among Chinese patients yet few studies have been conducted to study the factors associated with their compliance, discontinuation, and switching profiles. From clinical databases we studied 20,156 patients prescribed a CCB as their antihypertensive monotherapy from January 2004 to June 2007 in a large Territory of Hong Kong. We evaluated their compliance by medication possession ratios (MPRs), cumulative incidences of discontinuation and switching within 180 days after the prescription; and evaluated their associated factors using multivariable logistic regression analyses. The crude compliance level, discontinuation and switching rates at 180 days were 85.0, 3.1, and 5.0%, respectively. Older patients (aged > or =50 years; adjusted odds ratio (aOR) 1.21-1.34, P < 0.001), female gender (aOR 0.89, 95% confidence interval (CI) 0.82-0.96 for males, P = 0.004), fee payers (aOR 1.09, 95% CI 1.00-1.20, P = 0.050), service settings in family medicine specialist clinic (FMSC) (aOR 1.64, 95% CI 1.33-2.01, P < 0.001), and follow-up visits (aOR 3.24, 95% CI 2.93-3.58, P < 0.001) were positively associated with good compliance. Younger age and new visits were significantly associated with drug discontinuation or switching. Younger patients, male subjects, and new visitors were more likely to be noncompliant to CCB among ethnic Chinese. They represent the target subjects where primary care physicians should spend more effort on patient education to improve drug compliance.