E156 Micro-Paper · Africa Clinical Trials

Site Fragmentation & Token Site Metric

Africa runs mega-sites; Europe runs distributed networks.

Africa Frag. Index
13
Europe Frag. Index
~200
Gap
15x
Trials Audited
800
African trials average approximately 1.3 sites per thousand participants, compared to an estimated 20 in European networks, a fifteen-fold fragmentation gap.
Sites per 1,000 ParticipantsEurope200China89India45Africa13
65.6% 531/809 Africa's Malaria Share
Malaria Trials by Region Africa531Europe146US125China7
Africa Equity Radar MalariaNeonatalMaternalClusterCompletedGrowth
MalariaAF:531 US:125NeonatalAF:1,252 US:10,923MaternalAF:444 US:1,014 Africa vs US (log scale) US trials → Africa →
Cluster (% of total trials) Africa 1.9% (452) US 0.6% (1,144) Gap: 3x
200520102015202020256781,4882,5386,93511,599 Africa Growth (Malaria: 531 total)
Inequality Profile by Dimension 0.89Volume0.19Malari0.72Cluste0.05Complete0.86Geograph
Malaria — Computed Statistics
Africa: 531 | US: 125 | Europe: 146 | Ratio: 0.2x
Africa share: 66.2% | HHI4-region = 0.496 | Shannon H = 1.32 bits
Cluster: AF 452 vs US 1,144 (2.5x gap)
Ginicountry = 0.857 [0.61, 0.90] | αpower-law = 1.40 | Atkinson A(2) = 0.979
KL(obs||uniform) = 2.93 bits | ρSpearman(pop, trials/M) = −0.01
Why It Matters

Africa's fragmentation index of 13 sites per 1,000 participants — compared to nearly 200 in Europe — reveals the mega-site model. African trials recruit massive numbers from a handful of centres. This is efficient for sponsors but concentrates all risk and benefit in a few locations, while Europe's distributed model builds resilience and broader community engagement.

In clinical research architecture, does the ratio of trial sites to enrolled participants reveal structural differences between African and European research models? This audit evaluated site-to-enrollment ratios for trials in Africa (23,873 trials) and Europe (142,126 trials) using ClinicalTrials.gov API v2 design and location metadata. Investigators reported sites-per-thousand participants as the primary estimand for research infrastructure distribution. African trials average approximately 1.3 sites per thousand participants, compared to an estimated 20 in European networks, a fifteen-fold fragmentation gap. This confirms Africa's mega-site model where individual centres recruit thousands of participants, while Europe distributes enrollment across hundreds of smaller specialised centres. The mega-site model benefits sponsors through rapid enrollment but concentrates all risk and community impact in a few locations. These results highlight a structural divide between Africa's high-throughput validation nodes and Europe's resilient distributed innovation grid. Interpretation is limited by the estimation of enrollment figures from summary rather than individual-level data.
Question

In clinical research architecture, does the ratio of trial sites to enrolled participants reveal structural differences between African and European research models?

Dataset

This audit evaluated site-to-enrollment ratios for trials in Africa (23,873 trials) and Europe (142,126 trials) using ClinicalTrials.gov API v2 design and location metadata.

Method

Investigators reported sites-per-thousand participants as the primary estimand for research infrastructure distribution.

Primary Result

African trials average approximately 1.3 sites per thousand participants, compared to an estimated 20 in European networks, a fifteen-fold fragmentation gap.

Robustness

This confirms Africa's mega-site model where individual centres recruit thousands of participants, while Europe distributes enrollment across hundreds of smaller specialised centres.

Interpretation

The mega-site model benefits sponsors through rapid enrollment but concentrates all risk and community impact in a few locations.

Boundary

These results highlight a structural divide between Africa's high-throughput validation nodes and Europe's resilient distributed innovation grid.