Comparison of the Incidence of Adverse Events Between Japanese and Non-Japanese Healthy Subjects in Phase I Studies: A Systematic Review and Meta-Analysis.

Background and objective: Ethnic and racial differences are key factors affecting the results of clinical studies. However, the influence of these factors on the efficacy and safety of medicinal products remains unclear. Race-dependent nature is considered to be one of the factors causing differences in clinical findings, and we investigated its influence on the safety evaluation of drugs.

Methods: We searched PubMed and a Japan drug approval list to find relevant studies, and extracted phase I studies conducted with Japanese and non-Japanese participants using the same protocol and at the same study site. Pooled estimates of odds ratios (ORs) for the incidence of major adverse events in Japanese and non-Japanese participants were calculated, using a DerSimonian-Laird method with a random-effects model.

Results: Odds ratios for some adverse events in the active drug arm were significantly lower in Japanese participants: headaches [OR 0.65 (95% confidence interval [CI] 0.52-0.82), p = 0.0003], neurological disorders NEC [OR 0.70 (95% CI 0.53-0.93), p = 0.0135] in a High-Level Group Term, nervous system disorders [OR 0.64 (95% CI 0.49-0.82), p = 0.0004], infections and infestations [OR 0.71 (95% CI 0.53-0.95), p = 0.0202], and musculoskeletal and connective tissue disorders [OR 0.66 (95% CI 0.48-0.91, p = 0.0107] in the System Organ Class.

Conclusions: Our research suggested that racial factors such as race-dependent nature influence a drug safety assessment. With knowledge of these differences, it is expected that Japan will actively conduct multi-regional clinical trials, in which more diverse populations are included.