# Temporal Persistence

In the longitudinal analysis of research systems, has Africa's share of global clinical trials changed meaningfully over the past twenty-five years? This time-series audit tracked trial registration volumes across five epochs from 2000 to 2025 using ClinicalTrials.gov first-posted-date metadata for Africa (23,873 total) and comparator regions. Investigators reported the Africa-to-global volume ratio per epoch as the primary estimand for temporal persistence of research inequity. Africa grew from 678 trials in 2000-2005 to 11,599 in 2021-2025, a 17x increase, while the United States grew 2.9x over the same period. Despite this impressive absolute growth, Africa's share of global trials remained below six percent throughout all five epochs. The persistence of a stable volume ratio across two decades suggests a structural equilibrium maintained by systemic forces rather than a transient gap. These findings indicate that proportional equity requires policy intervention beyond organic growth. Interpretation is limited by retrospective registration of older trials.

## References

1. Alemayehu C, et al. "Behind the mask of the African clinical trials landscape." Trials. 2018;19:519.
2. Drain PK, et al. "Global migration of clinical trials." Nat Rev Drug Discov. 2018;17:765-766.

## Note Block

- Type: research
- App: https://mahmood726-cyber.github.io/africa-e156-students/geographic-equity/dashboards/angle-4_temporal-persistence.html
- Code: https://github.com/mahmood726-cyber/africa-e156-students/blob/master/geographic-equity/code/angle-4-temporal-persistence.py
- Data: ClinicalTrials.gov API v2
- Date: 2026-04-05