Medium matters: modeling the impact of solid medium performance on tuberculosis trial sample size requirements

Area of Science:

• Clinical microbiology
• Infectious disease research
• Biostatistics

Background:

• Two-month solid medium culture conversion is a standard endpoint in phase 2 anti-tuberculosis treatment trials.
• Current methods are suboptimal, potentially impacting trial efficiency and sample size requirements.

Purpose of the Study:

• To model how solid medium performance characteristics affect sample size in tuberculosis clinical trials.
• To quantify the impact of sensitivity and contamination rates on required participants for a two-arm study.

Main Methods:

• A simulation model was used to assess sample size.
• The model incorporated varying levels of solid medium sensitivity and contamination rates.
• Target culture conversion rates were set at 85% for the control arm and 95% for the experimental arm.

Main Results:

• Reducing contamination from 30% to 1% and increasing sensitivity from 60% to 95% decreased sample size per arm from 239 to 138.
• Higher sensitivity and lower contamination rates directly correlate with reduced sample size needs.

Conclusions:

• Optimizing solid medium performance is crucial for tuberculosis clinical trials.
• Improvements can lead to substantial reductions in sample size, increasing overall trial efficiency and potentially reducing costs.