Figure 2.

Variables predictive of 2-month sputum conversion in 142 patients. Pharmacokinetic parameters as well as patient demographic factors were examined in the initial models and the decision trees. Peak concentrations (mg/L) of pyrazinamide, rifampin, and isoniazid were the best predictors of 2-month sputum conversion. Only 2% of patients with a pyrazinamide peak above threshold were still sputum positive at 2 months. In those who had a lower pyrazinamide peak (more likely to fail), a high rifampin peak was associated with a positive 2-month sputum in only 3% of patients.