Missing Doses Erases Most of Blood Pressure Drugs' Heart Protection, Trial Data Shows

An estimated 1.4 billion adults aged 30 to 79 worldwide have high blood pressure, a condition that can quietly damage blood vessels and organs while raising the risk of heart disease, stroke and heart failure. Medication can substantially lower that risk, yet roughly half of patients do not take their prescribed treatment consistently. New research presented at the European Society of Cardiology (ESC) Congress 2026 by Qianqian Yang of the University of Oxford, UK, set out to measure how much that inconsistency costs patients, using randomized trial data rather than the observational studies that earlier evidence relied on.

The analysis combined individual data from 91,339 participants across nine clinical trials, each comparing an antihypertensive treatment with a placebo or a less intensive regimen. Participants were classed as having higher adherence if they took at least 80% of their assigned treatment, and lower adherence if they fell below that threshold. Even within closely monitored trials, adherence declined over time, with the share of participants in the higher-adherence group falling from 88% in the first year to 79% by year five.

Among participants with higher adherence, treatment lowered systolic blood pressure by 5.2 mmHg compared with the alternative approach, versus a reduction of only 3.0 mmHg in the lower-adherence group. Looking at major cardiovascular events, stroke, heart attack or ischemic heart disease, and heart failure requiring hospitalization or resulting in death, treatment cut these events by 11% in the higher-adherence group, but showed no significant reduction among those with lower adherence. 'Drugs don't work in patients who don't take them,' Yang said.

The researchers recommend making adherence assessment a routine part of hypertension care, alongside practical measures such as simplifying treatment schedules, combining several medications into one pill, and prescribing longer-acting drugs that still offer protection when an occasional dose is missed. The study was funded by the British Heart Foundation.