Methodological quality of meta-analyses on the blood pressure response to exercise: a review

Numerous meta-analyses have been conducted to summarize the growing numbers of trials addressing the effects of exercise on blood pressure (BP), yet it is unclear how well they have satisfied contemporary methodological standards. We applied an augmented version of the Assessment of Multiple Systematic Reviews (AMSTAR(ExBP)) scale to 33 meta-analyses retrieved from searches of electronic databases. Qualifying reports used meta-analytic procedures; examined controlled exercise training trials; had BP as a primary outcome; and had exercise or physical activity interventions independently or combined with other lifestyle interventions. AMSTAR(ExBP) scores averaged near the middle of the scale (Mean = 56.0% +/- 21.4% of total items possible); co-authored and more recent meta-analyses had higher quality scores. Common deficits were failures to disclose full search details (30% did), gauge the quality of included trials (48% did), use duplicate study selection and data extraction (55% did), or incorporate study quality in formulating results (35% did). Nearly all (91%) meta-analyses observed that exercise significantly lowered BP; fewer (58%) found that such effects depended on exercise or patient characteristics but these patterns often conflicted. Meta-analyses are often pillars of clinical recommendations and guidelines, yet only 58% addressed the clinical translations of their findings. In sum, meta-analyses have contributed less than ideally to our understanding of how exercise may impact BP, or how these BP effects may be moderated by patient or exercise characteristics. Future meta-analyses that better satisfy contemporary standards offer considerable promise to understand how and for whom exercise impacts BP.