Predicting TB treatment outcomes using baseline risk and treatment response markers: developing the PredictTB early treatment completion criteria

Standard treatment of drug-sensitive pulmonary tuberculosis requires six months of treatment. Several randomized clinical trials have attempted to shorten treatment to four months using various strategies but thus far all have failed. The PredictTB trial is an ongoing international randomized clinical trial testing a treatment shortening strategy whereby only drug-sensitive pulmonary TB patients who meet the study early treatment completion criteria are randomized to four vs. six months of treatment. The PredictTB early treatment completion criteria were developed based on a cohort of 92 pulmonary tuberculosis patients treated programmatically through the local tuberculosis treatment program in Cape Town, South Africa, with FDG-PET/CT scans also performed at baseline and week 4 of treatment. Patients were followed for one year after the end of therapy for programmatic treatment outcomes. This methodology paper describes how the PET/CT scans and GeneXpert cycle threshold data of this cohort were analyzed to develop the early treatment completion algorithm currently being used in the PredictTB trial.