# Spatial Equity Indices

In global research equity, can a composite spatial equity index capture the multidimensional geographic disadvantage facing African clinical trial participants? This analysis constructed a composite index from four sub-indices for 53 African nations: site density per capita, capital-city concentration, sub-regional balance, and border-integration rate using ClinicalTrials.gov data. Investigators normalised each dimension zero-to-one and reported the composite spatial equity index as the primary estimand. Africa scored 0.18 on the composite index compared to 0.74 for Europe and 0.81 for the United States, indicating a four-fold spatial equity deficit. Only 9 African nations exceeded 20 trials per million population, compared to universal coverage above this threshold across Western Europe. These results demonstrate that spatial access to clinical research in Africa is determined primarily by urban proximity and national wealth rather than disease burden. Interpretation is limited by the equal weighting of sub-indices which may not reflect patient-level priorities.

## References

1. Lang T, Siribaddana S. "Clinical trials have gone global: is this a good thing?" PLoS Med. 2012;9:e1001228.
2. Drain PK, et al. "Global migration of clinical trials." Nat Rev Drug Discov. 2018;17:765-766.
3. World Health Organization. "World Health Statistics 2024." WHO, Geneva.

## Note Block

- Type: research
- App: https://mahmood726-cyber.github.io/africa-e156-students/geographic-equity/dashboards/angle-20_spatial-equity-indices.html
- Code: https://github.com/mahmood726-cyber/africa-e156-students/blob/master/geographic-equity/code/angle-20-spatial-equity-indices.py
- Data: ClinicalTrials.gov API v2
- Date: 2026-04-05