Cardiovascular diseases (CVD), including heart attacks and strokes, are the leading cause of death and disability worldwide. Drug therapy with blood pressure and cholesterol lowering medications, particularly statins, have been proven to reduce the likelihood that individuals will experience a fatal or non-fatal cardiovascular event. Aspirin has also been proven to prevent heart attacks, certain types of strokes, and death in people with prior cardiovascular disease. The concept of fixed-dose combination therapy is to combine mulitple medications in a single pill as this has been shown to improve adherence in patients with high blood pressure and human immunodeficiency virus (HIV). There have been recent randomised controlled clinical trials to evaluate the effect of fixed-dose combination therapy for CVD prevention. The aim of this systematic review was to determine the effects of fixed-dose combination therapy on all-cause mortality, fatal and non-fatal CVD events, adverse events, blood pressure, lipids, discontinuation rates, quality of life, and costs for CVD prevention.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE until 2013. We found nine randomised controlled trials of two-drug through to five-drug fixed-dose combination therapy with placebo, single drug active component, or usual care in 7047 patients, dating from 2009 to 2013. Trials were generally short-term, ranging from six weeks to 15 months, and included middle-age adults with and without prior CVD.
Compared with placebo, single drug active component, or usual care, the effects of fixed-dose combination therapy on all-cause mortality or CVD events were uncertain. However, the event rates for these outcomes were relatively uncommon, only two out of nine trials reported these outcomes, these trials were primarily designed to observed changes in CVD risk factor levels rather than clinical events, and the trials had a high risk of bias in at least one domain, suggesting that these results should not viewed with confidence. Of 1000 people treated with fixed-dose combination therapy during the study period, 297 (range 264 to 315) would experience a side effect compared with 242 people treated with placebo. Fixed-dose combination therapy was associated with lower systolic blood pressure (-7.05 mmHg, range -10.18 to -3.87) and total cholesterol (-0.75 mmol/L, range -1.05 to -0.46). However, there was a high degree of statistical heterogeneity in these comparisons so these results should be viewed with caution. Of 1000 patients treated with fixed-dose combination therapy during the study period, 140 (range 122 to 186) would discontinue the therapy compared with 115 patients treated with placebo. The effects on quality of life were uncertain, and no cost data were reported. Ongoing trials of fixed-dose combination therapy will likely inform these important endpoints.