Do group-delivered interventions improve control of high blood pressure in hypertension?

Problem

High blood pressure (hypertension) is the leading global cause of cardiovascular disease. Effective interventions to improve control of high blood pressure (BP) and minimise subsequent cardiovascular risk are needed. Individual patient interventions are effective but resource intensive. Primary Care Networks present opportunities to share resources and deliver care to groups of patients. This may be more efficient, and more cost-effective, than individual interventions. However, current evidence for effectiveness of group-based interventions is equivocal. Therefore, we sought to summarise the current literature to inform design of a future group-based hypertension intervention.AimTo determine whether group-based interventions for hypertension achieve improved BP outcomes in comparison to usual care.

Approach

We undertook a systematic review and meta-analysis. We searched MEDLINE, Embase, CENTRAL and CINAHL from inception to 30th August 2019, for randomised controlled trials comparing group-based interventions for hypertensive adults (>18 years) with usual care, delivered in primary care, outpatient or community settings. Primary outcome measures were change in BP and attainment of BP targets. Secondary outcomes were costs and cost-effectiveness of interventions. Study level data were extracted by two reviewers, with disagreements adjudicated by a third. Pooled estimates of BP changes were compared between interventions and usual care in random effects meta-analyses. Statistical heterogeneity was quantified using I2 statistics. Study quality was assessed using the Cochrane Risk of Bias (RoB2) tool; publication bias was assessed using funnel plots and Egger’s tests. Update searches were run on 5th January 2022; resulting data extractions will be completed before conference and final results presented. Study registered at PROSPERO: CRD42019145126.

Findings

After de-duplication, 5109 unique titles and abstracts were screened, 235 full texts assessed, and 57 cohorts included (n=4 qualitatively, n=53 in meta-analyses). Studies mainly took place in community (n=31) or primary care (n=14) settings. Interventions were predominately through education, exercise, or lifestyle instruction. Educational interventions reduced systolic blood pressure by 5.4 (95%CI 2.1 to 8.6) mmHg, exercise by 6.7 (4.1 to 9.3) mmHg and lifestyle interventions by 4.7 (2.3 to 7.1) mmHg more compared to usual care (p=0.002 for differences between intervention groups). Heterogeneity was substantial (I2>75% for each intervention group); for exercise interventions heterogeneity was largely explained by variation in intensity of interventions. Only 9 studies reported BP control rates, without evidence of improvement from interventions compared to usual care (risk difference 0.026, 95%CI -0.004 to 0.056; I2 = 7.4%). Secondary outcomes were poorly reported. Only 8 (15%) studies were judged to be at low risk of bias, limiting sensitivity analysis by study quality. There was no evidence of small study or publication bias.

Consequences

Moderate strength evidence suggests that greater BP lowering is achieved, compared to usual care, with group-based exercise, educational, and lifestyle interventions. Further high quality studies are required.