A plethora of studies show that significant gaps between evidence and its implementation are global problems, particularly in chronic diseases like hypertension. These gaps become even greater since the adherence declines markedly over time. The adherence of antihypertensive medications is generally in the range of 50-60% after one-year of antihypertensive treatment. Efforts to reduce these gaps will confer greater population benefits than most novel treatments and should be a priority for tackling the global burden of hypertension.
　　Efforts to improve adherence are focused on three sectors: health-care system, patient-doctor relationship, and drugs. Based on the published literature, it is noteworthy that, compared to reforms on health-care system and facilitation of patient-doctor relationship, simplification of drugs prescribed is the most effective way to improve adherence. Therefore, most hypertension guidelines recommend the use of fixed-dose single-pill combinations (SPCs) of antihypertensive drugs to improve adherence. However, previous evidence showing that SPCs were associated with better adherence were from studies with parallel designs and not adjusted for comorbidities and concomitant medications. There are no reported studies assessing the effects of antihypertensive SPCs on adherence in real-world hypertensive patients switched from free combinations to the corresponding SPCs. In the retrospective cohort study with a 1-year mirror-image design based on the national representative claim-based database in Taiwan, we not only demonstrated an unacceptably low adherence (1-year medication possession ratio [MPR] ~40%) to 2 antihypertensive drugs given separately in hypertensive patients treated with at least 2 antihypertensive drugs, but also showed a significant 75% relative increase in 1-year MPR with the strategy of switching to the corresponding SPCs. More importantly, despite of the seemingly “magic bullet” effect of SPCs on improving medication adherence, this strategy is not effective and may even worsen adherence in hypertensive patients adequately adhering to their original free-combined antihypertensive regimens (with an MPR ?0.8). On the other hand, switching from free-combined antihypertensive drugs to their corresponding SPCs is more effective in improving adherence in hypertensive patients treated with fewer (<3) antihypertensive drugs (i.e. less pill burden). These findings held after adjustments for the phenomenon of regression to the mean and suggest early or even initial use of SPCs to curtail the gaps between evidence and sustained implementation of antihypertensive therapy. Other strategies and tips to detect and improve antihypertensive medication adherence will also be discussed in the lecture.