Reach and representativeness within a rural randomized controlled trial designed to improve community health through civic engagement for built environment change in Texas and New York

Background Community-based trials are important for developing effective, real-world health improvement approaches that address built environment changes, but they often lack rural representation. This paper reports on community (n = 12) and study participant (n = 2420) characteristics of the Change Club (CC) project. Study participant characteristics are compared to publicly available data to determine reach and representativeness, and therefore, generalizability. Methods Weighted means of publicly available data by Zip Code Tabulation Area were calculated for community characteristics. Reach was calculated as the proportion of study participants enrolled in each community out of the total number of adults in the community. Participant means for each community were calculated for sociodemographic and health variables. Chi-square statistics and ratios of study participants to target populations were also calculated. Results On average, the CC study reached 1.3 % of the adult population across communities. Study communities were similar to rural nationwide and rural state populations in sociodemographic and health variables with some exceptions related to race and ethnicity. The study participant population was similar to their community population in many characteristics but differed in few (e.g., in 2–3 communities, participants were less likely to be older than 65; less likely to be Black or Hispanic; more likely to be unemployed; and/or less likely to be in fair or poor health). Conclusions These findings indicate that the CC study had reach and representativeness of rural communities and their residents in ranges similar to previous rural studies. Clearer standards for comparing differences between study samples and target populations are needed to ensure generalizability of future trials.