Combination pills boost antihypertensive compliance

By David Douglas

NEW YORK (Reuters Health) - Switching from separate antihypertensive drugs to fixed-dose single-pill combinations (SPCs) improves adherence in many patients, Taiwanese researchers say.

In a January 20th online paper in Hypertension, Dr. Tzung-Dau Wang of National Taiwan University Hospital, Taipei and colleagues note that SPCs have been advocated by several hypertension management guidelines, but there are no reported studies assessing the effects of SPCs on adherence in real-world patients with hypertension switched from free drug combinations.

In fact, Dr. Wang told Reuters Health by email, "long-term medication adherence (to antihypertensive drugs) is far from ideal (only about 40%) in the real world, and SPC is currently the most effective way to improve adherence, if compared with strategies like reducing the copayment, telemonitoring, etc."

To investigate further, the researchers reviewed data on 896 patients who were initially prescribed an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker and a thiazide-type diuretic as separate agents.

Compliance during one year on this regimen was compared to that for a further year following a switch to the same drugs prescribed as SPCs. Adherence was measured by medication possession ratio (MPR).

The MPR increased significantly from 42% in the pre-switch period to 69% thereafter (a 75% relative difference). However, the improvement was seen mainly in patients with poor compliance. Unexpectedly, those with high adherence showed an absolute drop of 13%.

The clinical significance of this "intriguing" finding, say the investigators is still not certain, but "it seems prudent to maintain free-combined antihypertensive drugs for patients with high medication adherence, given the lack of evidence that SPCs do improve medication adherence in this subset of patients with hypertension, particularly in countries where the choice of different doses of SPCs is limited."

In multivariate analysis, MPR difference was inversely related to the pre-switch MPR, the number of other antihypertensive drugs, and congestive heart failure.

"The benefit is particularly pronounced if SPC is prescribed early," Dr. Wang added, "or even at the start of antihypertensive treatment because our nation-wide claim data showed that SPC is much more effective in improving adherence for hypertensive patients taking fewer than three antihypertensive drugs and those who were less compliant to free combinations of antihypertensive drugs."

Overall, the researchers conclude, "These findings suggest early or even initial use of SPCs to curtail the gaps between evidence and sustained implementation of antihypertensive therapy. Whether this strategy will improve patient outcomes merits further investigations."

SOURCE: http://bit.ly/1n7C3iY

Hypertension 2014.

(c) Copyright Thomson Reuters 2014. Click For Restrictions - http://about.reuters.com/fulllegal.asp