# Longitudinal Velocity: 15-Year Trend

In time-series analysis, has the absolute and proportional gap between African and high-income research volumes narrowed over fifteen years of clinical trial registration? This longitudinal audit tracked registration volumes across five epochs from 2000 to 2025 using ClinicalTrials.gov metadata for 23,873 African and 190,644 United States trials. Africa grew from 678 trials in 2000-2005 to 11,599 in 2021-2025, while the United States grew from 16,409 to 48,234. The absolute gap widened from 15,731 trials in 2000-2005 to 36,635 in 2021-2025 despite Africa's faster percentage growth rate. Hub concentration remained static with Egypt, South Africa, and Kenya dominating throughout all epochs. These findings demonstrate that the research divide is a structural equilibrium resistant to 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/methods-systems/dashboards/longitudinal-velocity.html
- Code: https://github.com/mahmood726-cyber/africa-e156-students/blob/master/methods-systems/code/longitudinal-velocity.py
- Data: ClinicalTrials.gov API v2
- Date: 2026-04-05