Journal Article

Fixed-dose combination antihypertensive medications, adherence, and clinical outcomes: A population-based retrospective cohort study

Mamdani, Muhammad M., Tadrous, Mina, Khuu, Wayne, Verma, Amol A., Gomes, Tara

2018

Overview

The majority of people with hypertension require more than one medication to achieve blood pressure control. Many patients are prescribed multipill antihypertensive regimens rather than single-pill fixed-dose combination (FDC) treatment. Although FDC use may improve medication adherence, the impact on patient outcomes is unclear. We compared clinical outcomes and medication adherence with FDC therapy versus multipill combination therapy in a real-world setting using linked clinical and administrative databases. We conducted a population-based retrospective cohort study of 13,350 individuals 66 years and older in Ontario, Canada with up to 5 years of follow-up. We included individuals who were newly initiated on one angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II-receptor blocker (ARB) plus one thiazide diuretic. High-dimensional propensity score matching was used to compare individuals receiving FDC versus multipill therapy. The primary outcome was a composite of death or hospitalization for acute myocardial infarction (AMI), heart failure, or stroke. We conducted 2 analyses to examine the association between adherence and patient outcomes. First, we performed an on-treatment analysis to determine whether outcomes differed between groups while patients were on treatment, censoring patients when they first discontinued treatment, defined as not receiving medications within 150% of the previous days' supply. Second, we conducted an intention-to-treat analysis that followed individuals allowing for breaks in treatment to quantify the difference in drug adherence between groups and assess its impact on clinical outcomes. As expected, there was no significant difference in the primary outcome between groups in the on-treatment analysis (HR 1.06, 95% CI 0.86-1.31, P = 0.60). In the intention-to-treat analysis, the proportion of total follow-up days covered with medications was significantly greater in the FDC group (70%; IQR 19-98) than in the multipill group (42%, IQR 11-91, P < 0.01), and the primary outcome was less frequent in FDC recipients (3.4 versus 3.9 events per 100 person-years; HR 0.89, 95% CI 0.81-0.97, P < 0.01). The main limitations of this study were the lack of data regarding cause of death and blood pressure measurements and the possibility of residual confounding. Among older adults initiating combination antihypertensive treatment, FDC therapy was associated with a significantly lower risk of composite clinical outcomes, which may be related to better medication adherence.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Aged / Aged, 80 and over / Ambulatory care / Angiotensin II / Angiotensin Receptor Antagonists - therapeutic use / Angiotensin-converting enzyme inhibitors / Angiotensin-Converting Enzyme Inhibitors - therapeutic use / Antihypertensive agents / Antihypertensive Agents - therapeutic use / Antihypertensives / Blood / Blood pressure / Cerebral infarction / Clinical outcomes / Clinical trials / Cohort analysis / Cohort Studies / Combination drug therapy / Dosage and administration / Dose-response relationship / Dose-Response Relationship, Drug / Drug Dosage Calculations / Drug dosages / Drug therapy / Drug Therapy, Combination - statistics & numerical data / Enzyme inhibitors / Enzymes / Female / Health insurance / Heart diseases / Humans / Hypertension / Hypertension - drug therapy / Male / Medication Adherence - statistics & numerical data / Medicine and Health Sciences / Methods / Motivation / Myocardial infarction / Ontario / Patients / People and places / Peptidyl-dipeptidase A / Pharmacy / Population studies / Population-based studies / Prescription drugs / Retrospective Studies / Sodium Chloride Symporter Inhibitors - therapeutic use / Stroke / Systematic review / Treatment Outcome