Media matters: Modeling the impact of solid media performance on tuberculosis trial sample size requirements

SUMMARY

Setting

Two-month solid media culture conversion is a commonly used (if suboptimal) endpoint for phase 2 tuberculosis treatment trials.

Objective and Design

To model the effect of solid media performance characteristics (sensitivity and contamination rate) on required sample size for a two-arm clinical trial with 85% true (gold standard) culture conversion in the control and 95% in the experimental arm.

Results

Increasing sensitivity and decreasing contamination reduced sample size from 239 subjects/arm (60% sensitivity, 30% contamination) to 138 subjects/arm (95% sensitivity, 1% contamination).

Conclusion

Optimizing solid medium has significant potential to reduce sample size and increase tuberculosis clinical trial efficiency.