India, May 4 -- Africa bears a quarter of the world's disease burden yet is largely absent from top-tier clinical trials.

Only 3.9% of major trials were done exclusively in Africa, and just 0.6% of leading cardiovascular trials.

This exclusion undermines external validity, forcing doctors to apply poorly tested treatments to millions of African patients.

Modern medicine prides itself on being a universal science, built on evidence from clinical trials.

But there's a bias in medical research. While Africa accounts for roughly 25 per cent of the global disease burden and 19 per cent of the global population, the continent's people are largely invisible in some clinical trials.

The scale of the erasure is revealed in a landmark study of...