Adherence and persistence of single-pill ARB/CCB combination therapy compared to multiple-pill ARB/CCB regimens.
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.


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.


CONCLUSIONS
Patients using SPC ARB/CCB therapy were more likely to be persistent and adherent to treatment compared to patients taking free-combination therapy.
MedImpact Healthcare Systems, Inc., San Diego, CA, USA. fzeng@medimpact.com
F
F
Zeng
B V
BV
Patel
L
L
Andrews
F
F
Frech-Tamas
A E
AE
Rudolph
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D057911:Angiotensin Receptor Antagonists / Q000008:administration & dosage* / Q000009:adverse effects / Q000191:economics; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000191:economics; D002121:Calcium Channel Blockers / Q000008:administration & dosage* / Q000009:adverse effects / Q000191:economics; D020746:Calcium Channels, L-Type / Q000378:metabolism; D004338:Drug Combinations; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000191:economics / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013607:Tablets; D055815:Young Adult; D016903:Drug Monitoring
D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D004338:Drug Combinations; D013607:Tablets