Interpreting population reach of a large, successful physical activity trial delivered through primary care

BMC Public Health. 2018 Jan 23;18(1):170. doi: 10.1186/s12889-018-5034-4.


Background: Failure to include socio-economically deprived or ethnic minority groups in physical activity (PA) trials may limit representativeness and could lead to implementation of interventions that then increase health inequalities. Randomised intervention trials often have low recruitment rates and rarely assess recruitment bias. A previous trial by the same team using similar methods recruited 30% of the eligible population but was in an affluent setting with few non-white residents and was limited to those over 60 years of age.

Methods: PACE-UP is a large, effective, population-based walking trial in inactive 45-75 year-olds that recruited through seven London general practices. Anonymised practice demographic data were available for all those invited, enabling investigation of inequalities in trial recruitment. Non-participants were invited to complete a questionnaire.

Results: From 10,927 postal invitations, 1150 (10.5%) completed baseline assessment. Participation rate ratios (95% CI), adjusted for age and gender as appropriate, were lower in men 0.59 (0.52, 0.67) than women, in those under 55 compared with those ≥65, 0.60 (0.51, 0.71), in the most deprived quintile compared with the least deprived 0.52 (0.39, 0.70) and in Asian individuals compared with whites 0.62 (0.50, 0.76). Black individuals were equally likely to participate as white individuals. Participation was also associated with having a co-morbidity or some degree of health limitation. The most common reasons for non-participation were considering themselves as being too active or lack of time.

Conclusions: Conducting the trial in this diverse setting reduced overall response, with lower response in socio-economically deprived and Asian sub-groups. Trials with greater reach are likely to be more expensive in terms of recruitment and gains in generalizability need to be balanced with greater costs. Differential uptake of successful trial interventions may increase inequalities in PA levels and should be monitored.

Trial registration: ISRCTN98538934 . Registered 2nd March 2012.

Keywords: Non-participation; Physical activity; Primary care; Randomised trials; Recruitment.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Community Participation / statistics & numerical data*
  • Ethnic Groups / statistics & numerical data
  • Exercise*
  • Female
  • Health Promotion / organization & administration*
  • Health Status Disparities
  • Humans
  • London
  • Male
  • Middle Aged
  • Minority Groups / statistics & numerical data
  • Poverty
  • Primary Health Care*
  • Program Evaluation
  • Sedentary Behavior / ethnology
  • Surveys and Questionnaires
  • Walking / statistics & numerical data