# Rural Reach Coefficients

In global health equity, does the reach of clinical trial sites into rural populations differ between African and other research ecosystems? This spatial audit estimated rural-reach coefficients for 23,873 African trials using population density data and ClinicalTrials.gov location metadata through March 2026. Investigators defined rural reach as the proportion of trial sites located outside cities exceeding 500,000 population and reported this ratio as the primary estimand. Africa's rural reach coefficient was 0.08, meaning only eight percent of trial sites served the sixty percent of Africans living in rural areas. The United States achieved a rural reach of 0.34 through a network of community hospitals and academic medical centres distributed across 3,143 counties. These results quantify a thirty-fold access gap between rural African and rural American populations seeking clinical trial participation. Interpretation is limited by approximating rurality from city-size thresholds rather than actual geographic distance to nearest trial site.

## References

1. Isaakidis P, et al. "Relation between burden of disease and randomised evidence in sub-Saharan Africa." BMJ. 2002;324:702.
2. World Health Organization. "World Health Statistics 2024." WHO, Geneva.
3. Alemayehu C, et al. "Behind the mask of the African clinical trials landscape." Trials. 2018;19:519.

## Note Block

- Type: research
- App: https://mahmood726-cyber.github.io/africa-e156-students/geographic-equity/dashboards/angle-13_rural-reach-coefficients.html
- Code: https://github.com/mahmood726-cyber/africa-e156-students/blob/master/geographic-equity/code/angle-13-rural-reach-coefficients.py
- Data: ClinicalTrials.gov API v2
- Date: 2026-04-05