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. METHODS: Rapid evidence assessment conducted in MEDLINE, EMBASE, and Cochrane Library (1 January 2013–11 January 2019) to identify studies investigating SPC therapy for adults with hypertension. Information on adherence/persistence, BP lowering/goal attainment, and cardiovascular outcomes/events were extracted via two-phase screening process. Studies not focusing on adherence, persistence, or compliance with SPC therapy were excluded. Methodological quality was assessed using appropriate scales. RESULTS: Of 863 citations, 752 failed to meet inclusion or were duplicates. Twenty-nine studies remained following full-text screening. Just four studies (14%) were randomized controlled studies; 25 (86%) were observational. A range of SPC therapies were studied, with calcium channel blocker/angiotensin receptor blocker combinations most common (11/29 studies). Adherence and persistence were generally higher with SPC vs. free-dose combination therapy; 15 studies (54%) directly compared adherence and four (14%) compared persistence. Patients achieving BP targets ranged from 25 to 89%. Despite all studies investigating patients with hypertension only 16 (55%) reported change in BP. Few studies reported on cardiovascular outcomes. Methodological reporting was often suboptimal. CONCLUSION: Adherence and/or persistence were generally higher in patients taking antihypertensives as SPC vs. free-dose combination; however, methodological reporting was suboptimal to facilitate comparison. Specifically designed, well reported studies are required to determine if the increased adherence/persistence seen in patients on SPC regimen leads to improved BP control and/or cardiovascular outcomes.