Benefits of strict adherence to an intensive structured care approach to blood pressure management in primary care within the intervention arm of a multicentre randomized controlled trial

Abstract

Purpose: We have recently shown that a structured and intensive strategy for BP management in primary care provides significant clinical benefits relative to usual care. We sought to determine levels and predictors of adherence to this strategy as well as its impact on BP control. Methods: Prospective, multi-centre randomised controlled trial (119 primary care clinics/2185 patients). The intervention comprised automated risk profiling plus standardised guideline-based, stepwise pharmacological treatment (initial ARB mono-therapy or two forms of single pill ARB combination therapy) and computer assisted intensified follow-up and treatment titration. Protocol adherence, including treatment prescription/up-titration plus the structured visits at 6, 10, 14 and 18 weeks post randomisation were assessed for the 1038 patients randomised to the intervention arm. A score of 1-5 for protocol adherence was derived and examined relative to BP control during 26 weeks follow-up. Results: Mean age was 59.2+11.8 years, 62% were male and 67% had longstanding hypertension. At randomisation, mean BP was 150+17/88+11 mmHg with individual BP targets of <140/90mmHg, <130/80mmHg and <125/75mmHg in 29.3%, 53.7% and 17.1% of patients. Adherence to the structured clinic visits ranged from 83-91% (59-86% + 7 days of schedule) with a post-randomisation visit recorded in 95% of patients. At randomisation, 93% of patients were prescribed per-protocol treatment. Thereafter, adherence to the treatment protocol (including treatment up-titration) ranged from 61.3%-74.2%. Minimum and maximal per-protocol adherence occurred in 200 (19.3%) and 270 (26.0%) patients respectively: this was reflected in significantly (p<0.001) lower BP levels (132+14/79+9 vs. 141+15/83+11 mmHg) and attainment of BP target (51.1 vs. 19.0%) in the latter group. Independent correlates (adjusted p<0.05) of perprotocol adherence (score of 4 or 5) were the individual BP target, initial systolic BP, treatment group (mono- versus combination ARB therapy), race, type of clinic and presence of a practice nurse. Increasing per-protocol adherence was independently correlated with reaching individual BP control (OR 1.41, 95% 1.27 - 1.58 per point). Conclusions: Stricter adherence to an intensive and structured approach to hypertension management within the intervention arm of one of the largest BP management studies of its kind resulted in significantly enhanced levels of BP control. Applying refined strategies to optimise the potential of this type of intervention (including overcoming prescription resistance) are of clinical importance to optimise BP control