Adherence and Persistence of Single-Pill ARB/CCB Combination Therapy Compared to Multiple-Pill ARB/CCB Regimens

Curr Med Res Opin. 2010 Dec;26(12):2877-87. doi: 10.1185/03007995.2010.534129. Epub 2010 Nov 11.


Objective: To evaluate the impact of angiotensin receptor blocker (ARBs)/dihydropyridine calcium channel blockers (CCBs) single-pill combination (SPC) on adherence to antihypertensive treatment in comparison to free combination of ARBs and CCBs.

Research design and methods: A retrospective data analysis was performed using pharmacy claims data from a national pharmacy benefit management company. The study included patients who were newly initiated on ARB/CCB treatment between 01/01/2007 and 08/31/2008, aged ≥ 18 years, and continuously enrolled in the same health plan for 12 months prior to and 13 months after starting ARB/CCB treatment. Outcome variables were persistence, defined as time to discontinuation of therapy, and adherence, defined as proportion of days covered (PDC) ≥ 0.80. Propensity score weighting was used to balance the characteristics of the two groups.

Results: The final sample contained 2312 patients in the free-combination group and 2213 patients in the SPC group. Patients in the SPC group and the free-combination group were different in age, gender, type of insurance, history of antihypertensive therapy and co-morbidities. These differences were largely normalized after propensity score adjustment. Multivariate logistic model regression showed that patients in the SPC group had a 90% greater odds of being adherent to index therapy compared to patients in the free-combination group (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.75-2.08, p< 0.001). A Cox proportional hazards model showed that patients in the SPC group were less likely to discontinue ARB/CCB SPC therapy compared to patients in the free-combination group (hazard ratio [HR] 0.66, 95% CI 0.63-0.70, p < 0.001). In both models, higher copayment (copayment $50 and above) was associated with worse persistence and adherence in comparison to patients who had a lower copayment ($0-$5): HR = 1.23, p < 0.001 and OR = 0.67, p < 0.001.

Conclusion: Patients using SPC ARB/CCB therapy were more likely to be persistent and adherent to treatment compared to patients taking free-combination therapy.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Algorithms
  • Angiotensin Receptor Antagonists / administration & dosage*
  • Angiotensin Receptor Antagonists / adverse effects
  • Angiotensin Receptor Antagonists / economics
  • Antihypertensive Agents / administration & dosage
  • Antihypertensive Agents / adverse effects
  • Antihypertensive Agents / economics
  • Calcium Channel Blockers / administration & dosage*
  • Calcium Channel Blockers / adverse effects
  • Calcium Channel Blockers / economics
  • Calcium Channels, L-Type / metabolism
  • Drug Combinations
  • Drug Therapy, Combination
  • Female
  • Humans
  • Hypertension / drug therapy*
  • Hypertension / economics
  • Hypertension / epidemiology
  • Male
  • Medication Adherence* / statistics & numerical data
  • Middle Aged
  • Retrospective Studies
  • Tablets
  • Young Adult


  • Angiotensin Receptor Antagonists
  • Antihypertensive Agents
  • Calcium Channel Blockers
  • Calcium Channels, L-Type
  • Drug Combinations
  • Tablets