Are randomised control trials of physical activity interventions recruiting harder to reach participants from general practice: a systematic review

Background: General practice is well situated to promote physical activity (PA) among middle-aged and older adults, but often those who are most likely to benefit from interventions tend to be the least likely recruited to participate in research. This study aimed to systematically review the published literature pertaining to PA interventions in general practice settings, in order to investigate approaches to recruitment and study populations profiles.

Methods: Seven databases were searched, including: PubMed, CINAHL, the Cochrane Library Register of Controlled Trials, Embase, Scopus, PsycINFO and Web of Science. Only randomised control trials RCTs involving adults 45 years old or older recruited through primary care, were included. The PRIMSA framework for systematic review was followed, which involved two researchers independently conducting title, abstract and full article screening. Tools for data extraction and synthesis were adapted from previous work on inclusivity in recruitment.

Results: The searches retrieved 3491 studies, of which 12 were included for review. Sample size of the studies ranged from 31 to 1366 and a total of 6085 participants were included. Studies recorded characteristics of harder to reach populations. Participants tended to be urban based, white females with at least one pre-existing condition. Reporting of studies demonstrated a lack of ethnic minorities and lower numbers of males. Only one practice out of 139 was rural. Recruitment quality and efficiency was inconsistently reported.

Conclusion: Certain participants, including rural-based populations, are under-represented. RCT study design, recruitment and reporting must be improved to increase study sample representativeness so that those most in need of PA interventions are targeted and successfully recruited.