Blood pressure-lowering drugs reduced major cardiovascular events by 11% in trial participants who took at least 80% of their assigned medication, but produced no significant reduction in those who took less, according to a pooled analysis of 91,339 people from nine randomized trials presented at the European Society of Cardiology (ESC) Congress 2026 in Munich. The results, released by the ESC in late August and recirculated on Oct. 25 by ScienceDaily, have not yet appeared in a peer-reviewed journal.

The work was carried out within the Blood Pressure Lowering Treatment Trialists’ Collaboration (BPLTTC), led by Kazem Rahimi and Milad Nazarzadeh at the University of Oxford, and was presented on Aug. 30 by Qianqian Yang, a doctoral student at Oxford. It was funded by the British Heart Foundation. The analysis pooled individual participant data from trials that compared an antihypertensive regimen with either placebo or a less intensive regimen. Participants who took at least 80% of their assigned treatment were classed as higher adherence; the rest were classed as lower adherence.

Among higher-adherence participants, systolic blood pressure was 5.2 mmHg lower in the intervention group than in the comparator group (95% confidence interval 5.0 to 5.4), compared with 3.0 mmHg (2.7 to 3.3) among lower-adherence participants, according to figures reported by HCPLive. Major cardiovascular disease, defined as stroke, myocardial infarction, ischemic heart disease, or heart failure causing death or hospitalization, was 11% lower with treatment in the higher-adherence group (hazard ratio 0.89; 95% CI 0.86 to 0.92). In the lower-adherence group there was no significant reduction (hazard ratio 1.01; 0.92 to 1.10).

Adherence slipped even inside clinical trials. The share of participants classed as higher adherence fell from 88% in the first year to 79% by year five, the ESC release said. “A decline in adherence over time was apparent, even in the structured setting of trials,” Yang said. “Patients with lower adherence derived little or no cardiovascular benefit,” she added, according to the text carried by ScienceDaily. As she put it in the ESC release, “drugs don’t work in patients who don’t take them.”

The adherence analysis sits within a broader BPLTTC meta-analysis of 115,389 participants in 12 trials, with 15,460 major cardiovascular events and 9,591 deaths over a median follow-up of 4.7 years, HCPLive reported.

Felix Mahfoud, chair of the ESC Communication Committee, commenting for the society, said: “For years, we have neglected non-adherence to medication as a cause for uncontrolled hypertension.” He added that “assessment of adherence should become a routine part of hypertension care.”

Why it matters

An estimated 1.4 billion adults aged 30 to 79 have high blood pressure, and about half do not take their prescriptions as directed, according to the ESC release. The analysis puts a number on what that costs: in this dataset, the cardiovascular benefit of treatment was concentrated in people who took most of their pills. For patients, the message is that the protection documented in landmark trials assumes a level of adherence that many people do not reach, and that the blood pressure reduction itself was smaller when doses were missed.

For clinicians and health systems, the authors argue that adherence should be measured routinely rather than assumed. The ESC release lists practical steps: better patient education, simpler dosing schedules, single-pill combinations, and longer-acting drugs whose effect persists through an occasionally missed dose. Mahfoud said clinicians should have open, non-judgmental conversations with their patients about taking medication.

The caveats

These are conference findings. They were presented as an abstract and have not been peer reviewed or published in full, so the list of trials, the way adherence was recorded in each, and the statistical methods are not yet available for scrutiny. The ESC release does not report confidence intervals; the intervals above come from HCPLive’s account of the presentation.

Although every participant was randomized to treatment or comparator, nobody was randomized to adhere or not. The comparison between adherence groups is therefore observational, even though the trials themselves were randomized, and people who keep taking their pills may differ from those who do not in ways that also affect cardiovascular risk. The release reports results only for a single split at 80% adherence, so it does not describe what happens at intermediate levels.

What to watch

Publication of the full analysis in a peer-reviewed journal, which would allow the included trials, adherence measures and sensitivity analyses to be examined.

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