Does a nurse-led intervention improve medication adherence among older adults with hypertension in Spanish primary care? Protocol for a pragmatic cluster randomised controlled trial (NURSE-ADHERE-HTN)

Introduction: Poor long-term adherence to antihypertensive medication remains a major challenge in hypertension management, particularly among older adults, contributing to suboptimal blood pressure control, cardiovascular morbidity and reduced quality of life. Nurse-led educational and behavioural interventions delivered in primary care may improve medication adherence; however, evidence from pragmatic cluster randomised trials integrated into routine clinical practice remains limited. This study aims to evaluate whether a nurse-led multidimensional educational and behavioural intervention improves adherence to antihypertensive treatment among older adults with hypertension in primary care.

Methods and analysis: NURSE-ADHERE-HTN is an ongoing pragmatic, open-label, cluster randomised controlled trial being conducted in 14 primary care centres of the Navarra Health Service–Osasunbidea, Spain. The trial was prospectively registered in the ISRCTN registry (ISRCTN35559821). Primary care centres were centrally allocated in a 1:1 ratio to the intervention or usual-care group, with seven centres per group and two participating nurses per centre. The target sample size is 280 participants aged 60 years or older with hypertension, prescribed at least one antihypertensive medication and identified as non-adherent using the 4-item Morisky Medication Adherence Scale (MMAS-4). The intervention consists of a nurse-led multidimensional educational and behavioural programme integrated into routine primary care, comprising individualised education, motivational interviewing, review of antihypertensive treatment and medication-taking routines, Mediterranean diet counselling, physical activity support and telephone reinforcement. The primary outcome will be adherence to antihypertensive treatment at 6 months, assessed using the MMAS-4 in accordance with the licensed wording, structure and standardised scoring method. Adherence will also be assessed at baseline and 12 months, with the 12-month assessment used to evaluate whether any intervention effect observed at 6 months is maintained over time. Electronic prescription dispensing records will provide a complementary measure of adherence. Secondary outcomes will include blood pressure assessed using 24-hour ambulatory monitoring, health-related quality of life, cardiovascular-related emergency department visits and hospital admissions, symptoms of anxiety and depression, Mediterranean diet adherence, physical activity, reasons for non-adherence, anthropometric and selected laboratory variables, medication burden and concordance between adherence measures. Outcomes will be assessed at baseline, 6 months and 12 months. Prespecified exploratory analyses will assess effect modification by sex. Statistical analyses will account for clustering at the primary care centre level.