Low Adherence Cuts Cardiovascular Benefit of Blood Pressure Therapy

Reduced medication adherence significantly attenuates the cardiovascular benefit of antihypertensive therapy, according to an individual participant data (IPD) meta-analysis presented at the European Society of Cardiology (ESC) Congress 2026 in Munich, Germany.¹

The analysis, conducted within the Blood Pressure Lowering Treatment Trialists' Collaboration (BPLTTC), pooled longitudinal adherence data from 91,339 participants across 9 randomized trials.¹ Patients with higher adherence, defined as ≥ 80% of assigned treatment taken, saw significantly greater reductions in systolic blood pressure (SBP) and major cardiovascular events than patients with lower adherence.¹

Prior evidence linking adherence to antihypertensive outcomes has come largely from observational cohorts, not accounting for the possibility of confounding by unmeasured patient factors.¹ By analyzing randomized trial data and preserving randomization within adherence strata, the BPLTTC investigators isolated the effect of adherence itself on treatment benefit, rather than relying on observational comparisons across adherent and nonadherent patients.¹

“We have evidence that poor adherence to antihypertensive medication is associated with worse outcomes,” Qianqian Yang, a second-year DPhil student at the University of Oxford, said in a statement. “However, previous data has come from observational studies and could be confounded by other factors. We undertook an analysis of randomised trial data to assess the true impact of adherence on the benefits of antihypertensive treatment.” 

The meta-analysis harmonized adherence measures across included trials into a binary variable, at least 80% versus less than 80% of assigned medication taken, updated at each follow-up visit to capture longitudinal patterns.¹ Treatment effects on SBP were estimated using linear mixed-effects models, and treatment effects on clinical events were estimated using trial-stratified Cox models, with treatment-by-adherence interaction terms testing effect modification.¹

The overall meta-analysis, which included 115,389 participants from 12 trials, recorded 15,460 major cardiovascular events and 9591 deaths over a median follow-up of 4.7 years.¹

Blood Pressure and Cardiovascular Outcomes by Adherence Stratum

Compared with the comparator group, the intervention reduced SBP by 5.2 mm Hg (95% CI, 5.0-5.4) in the higher-adherence stratum, versus only 3.0 mm Hg (95% CI, 2.7-3.3) in the lower-adherence stratum (P for interaction < .001).¹ The treatment effect on major cardiovascular disease, defined as stroke, myocardial infarction or ischemic heart disease, and heart failure causing death or hospitalization, also differed significantly by adherence (P for interaction = .04).¹

Investigators reported an 11% reduction in major cardiovascular disease with higher adherence (HR, 0.89; 95% CI, 0.86-0.92), with no significant reduction in the lower-adherence stratum (HR, 1.01; 95% CI, 0.92-1.10).¹

Adherence Decline Over Time and Clinical Implications

Adherence declined over time in both intervention and comparator groups, even within the structured setting of a randomized trial.¹ Among participants with longitudinal adherence data, mean adherence was 88% in the intervention group and 87% in the comparator group at 1 year, falling to 80% and 77%, respectively, by 5 years.¹

“A decline in adherence over time was apparent, even in the structured setting of trials,” Yang noted.

According to the investigators, adherence assessment and education should occupy a more prominent role in routine hypertension management.¹ Proposed strategies to improve adherence include simplifying antihypertensive regimens, using single-pill combinations to reduce medication burden, and favoring longer-acting agents in which an occasional missed dose has less impact on blood pressure control.¹

“Our results reinforce the saying that ‘drugs don’t work in patients who don’t take them,’” Yang said. “Patients with lower adherence derived little or no cardiovascular benefit, whereas those with higher adherence had greater reductions in blood pressure and prevention of cardiovascular events.

“For years, we have neglected non-adherence to medication as a cause for uncontrolled hypertension. Assessment of adherence should become a routine part of hypertension care so patients do not miss out on life-saving benefits,” said Felix Mahfoud, Chair of the ESC Communication Committee. “As healthcare providers, we are here to have open, non-judgemental conversations with our patients about any barriers they may have to taking medication, to help improve adherence.”

References:

1. Yang Q, Nazarzadeh M, Rahimi K, et al. Adherence to antihypertensive therapy and cardiovascular outcomes: an individual participant data meta-analysis of randomised controlled trials. Presented at: ESC Congress 2026; August 30, 2026; Munich, Germany.

2. European Society of Cardiology. Patients are missing out on the cardiovascular benefits of blood pressure-lowering medicines. Published August 27, 2026. Accessed August 28, 2026.