Table 5.

Detectable effect size for common variants (minor allele frequency = 10%) as a function of the number of case samples versus 3000 controls

Sample size	Detectable relative risk at 80% power
783	1.7
200	2.3
100	2.9
30	5.1
10	10.8

Available sample sizes for stratified analyses include those on the order of 100–200 for injury type and other clinical strata, which should be able to detect moderate effects of common variants (genotype relative risk on the order of 2–3). Some drug-specific analyses were carried out using sample sizes in the range of 10–30 individuals, which have low power to detect moderate effects but are well powered to detect very large effects (genotype relative risks of 5–10 or greater). These estimates assume a minor allele frequency of 0.10, a control sample of 3000, a population prevalence of drug-induced liver injury 1 : 10 000, and a significance threshold P<10⁻⁸.