Fixed-Dose Combination Therapy in Hypertension

Impact of single-pill combination therapy on adherence, blood pressure control, and clinical outcomes: a rapid evidence assessment of recent literature

The 2018 European Society of Cardiology/European Society of Hypertension Guidelines for the management of arterial hypertension raised the need for evidence to support the use of single-pill combination (SPC) therapy in preference to free-dosed therapy for hypertension. This systematic rapid evidence assessment sought to determine if initiating SPC therapy improves adherence, blood pressure (BP) control and/or cardiovascular outcomes vs. initiation of free-dose combination therapy.

Antihypertensive polytherapy in Australia: prevalence of inappropriate combinations, 2013-2018

OBJECTIVES

To estimate the prevalence of inappropriate antihypertensive polytherapy in Australia.

METHODS

We used a nationally representative 10% sample of Pharmaceutical Benefits Scheme (PBS) eligible Australians and their dispensing history to identify people aged 18+ years exposed to at least one PBS-listed antihypertensive between 2012 and 2018. We measured prevalence of antihypertensive polypharmacy (≥40 days concomitant exposure), inappropriate antihypertensive combinations (against guideline recommendations; within-class polytherapy) and combinations to be used with caution.

RESULTS

Almost half (47.5%) of people using antihypertensives in 2018 experienced polytherapy. Among these, 2.4% had an inappropriate combination (1.5% against guidelines; 1.0% within-class polytherapy). Inappropriate combinations were more prevalent in people experiencing polytherapy with three (3.7%) or four (16.1%) antihypertensive medicines than people on dual therapy (0.7%). Inappropriate combinations occurred at a lower rate in people using fixed-dose rather than free-drug combinations for dual therapy (0 vs. 0.7%) and in those using three antihypertensives (2.4 vs. 7.3%); this was not the case for people using four or more antihypertensives (15.5 vs. 16.1%). Between 2013 and 2018, the prevalence of antihypertensive polytherapy was relatively stable (49-47%); however, the prevalence of inappropriate combinations among these patients halved (from 5.1 to 2.4%).

CONCLUSION

Antihypertensive polytherapy in Australia is common, but the prevalence of inappropriate combinations is low and decreasing over time, suggesting strong awareness of Australian clinical guidelines. However, in 2018, approximately 49 000 Australian adults experienced inappropriate polytherapy; prescribing of fixed-dose combinations in patients on dual or triple therapy may further reduce this inappropriate care, although increased vigilance treating patients with more than 3 antihypertensives is required.

Does the Polypill Improve Patient Adherence Compared to Its Individual Formulations? A Systematic Review

Many patients, especially those with a high pill burden and multiple chronic illnesses, are less adherent to medication. In medication treatments utilizing polypills, this problem might be diminished since multiple drugs are fused into one formulation and, therefore, the therapy regimen is simplified. This systematic review summarized evidence to assess the effect of polypills on medication adherence. The following databases were searched for articles published between 1 January 2000, and 14 May 2019: PubMed, Web of Science, Cochrane Library, and Scopus. Medication adherence was the only outcome assessed, regardless of the method of measuring it. Sixty-seven original peer-reviewed articles were selected. Adherence to polypill regimens was significantly higher in 56 articles (84%) compared to multiple pill regimens. This finding was also supported by the results of 13 out of 17 selected previously published systematic reviews and meta-analyses dealing with this topic. Adherence can be improved through the formulation of polypills, which is probably why the interest in researching them is growing. There are many polypills on the market, but the adherence studies so far focused mainly on a small range of medical conditions.

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

BACKGROUND

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.

METHODS AND FINDINGS

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.

CONCLUSIONS

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.

Implications of prescribing a fixed-dose combination in clinical cardiology practice: a retrospective observational study using a single medical centre database in Korea

Objective

Fixed-dose combination (FDC) prescribing enhances adherence to medication. However, there are limited data regarding the usefulness of FDC drugs across different risk groups. The aim of this study was to explore the relationship between FDC discontinuation and clinical outcomes.

Methods

From January 2008 to December 2014, patients with FDC prescriptions who visited a cardiology outpatient clinic at a tertiary university hospital in Daegu, Republic of Korea were retrospectively identified. The 10-year atherosclerotic cardiovascular disease (ASCVD) risk score and 20 conventional cardiovascular (CV) risk factors were assessed. Patients were classified according to FDC continuation, together with a tertile of 20 risks. CV events were defined as the composite of admission for worsening heart failure or diabetes, stroke, ischaemic heart disease, and CV death.

Results

502 patients were prescribed with one of the following FDC products: calcium channel blocker (CCB) plus angiotensin receptor blockers (ARB), CCB plus statins, and ARB plus diuretics. During follow-up (mean 2.8±2.4 years), 203 discontinuations (40.4%) occurred. FDC-discontinued patients had lower ASCVD risk scores (24.8% vs. 28.8%, p<0.001), and patients with <6 risk factors discontinued FDC frequently. During follow-up, 57 events (11.4%) were reported: 30 (14.8%) in FDC-discontinued patients and 27 (9.1%) in FDC-continued patients (p=0.062). In multivariate models accounting for events, FDC discontinuation (p<0.001) and high ASCVD risk score (p=0.017) were associated with CV events.

Conclusions

FDC discontinuation was common among patients attending the cardiology outpatient clinic. Our analyses suggest that FDC discontinuation in patients at high ASCVD risk may have an impact on CV event rates.

Comparison of therapy persistence for fixed versus free combination antihypertensives: a retrospective cohort study

OBJECTIVES

The aim of the study was to compare therapy persistence among patients who started with one of three drug regimens: a monotherapy, or combination therapy either as a fixed combination (ie, 'single pill') or as a free combination (ie, two separate antihypertensive agents).

DESIGN

In a secondary data analysis, we used descriptive statistics and multivariate logistic regression to measure the effect of the three therapy regimens on therapy persistence over 4 years.

SETTING

Prescription data from a large German statutory health insurance provider.

PARTICIPANTS

All patients who started with a new antihypertensive therapy in 2007 or 2008 (n=8032) were included and followed for 4 years.

PRIMARY OUTCOME MEASURE

Therapy persistence, defined as receiving a refill prescription no later than within 180 days.

RESULTS

The persistence rates after 4 years were nearly identical among patients who started with a monotherapy (40.3%) or a fixed combination of two drugs (39.8%). However, significantly more patients who started with free-drug combinations remained therapy persistent (56.4%), resulting in an OR of 2.00 (95% CI 1.6 to 2.5; p<0.0001) for free combinations versus fixed combinations. This trend was observed in all age groups and for men and women. At the end of the study period, the number of different antihypertensive agents was still similar between patients who started with a fixed combination (2.41) and patients who started with a free combination (2.28).

CONCLUSIONS

While single-pill combinations make it easier to take different drugs at once, the risk is high that these several substances are stopped at once. Therapy persistence was significantly better for patients who started with a free-drug combination without taking much fewer different antihypertensive drugs as those with a fixed combination.

How does prescribing for antihypertensive products stack up against guideline recommendations? An Australian population-based study (2006-2014)

AIMS

We describe choice of first-line antihypertensive drug therapy and uptake of fixed-dose combinations (FDCs) in Australia, and investigate the impact of initiation on FDCs and other non-recommended first-line therapies on treatment discontinuation.

METHOD

This was a population-based retrospective cohort study using a random 10% sample of persons dispensed an Australian Pharmaceutical Benefits Scheme listed medicine from 1 July 2005 to 30 June 2014. The primary outcomes were adherence to Australian recommendations at initiation of antihypertensive therapy, discontinuation of initial therapy and discontinuation of any therapy in the first year after initiation.

RESULTS

In our sample of 55 937 persons initiating therapy, 42.0% did so outside Australian recommendations, including not initiating on recommended monotherapy (26.3%) and not initiating on the lowest recommended dose (30.6%). Only 1.7% of individuals who were dispensed an FDC established therapy on the free combination regimen (as recommended) prior to switching. After adjusting for covariates, persons initiating on non-recommended monotherapy (OR = 2.64, 95% CI 2.47-2.83) or FDCs of two or more antihypertensives (OR = 1.42, 95% CI 1.30-1.55), were more likely to discontinue all antihypertensive drug treatment in the first year compared to persons initiating on recommended monotherapy.

CONCLUSION

More than half of antihypertensive initiators conformed to Australian guidelines. Initiation on FDCs and other non-recommended treatments was associated with lower persistence on antihypertensive therapy in the first year. Long-term effectiveness and outcomes may be enhanced by initiating with low dose monotherapy.