Table 4. Multivariable model 2 adjusted hazard ratios for sputum culture conversion associated with inclusion of one additional untested drug in the regimen, stratified by average number of effective drugs received per day and inclusion of pyrazinamide in the regimen.

Average Number of Effective Drugs Received per Day*	Pyrazinamide Included in Regimen
	No	Yes
0	0.78 (0.51–1.17)	0.52 (0.34–0.79)
1	0.94 (0.69–1.29)	0.63 (0.46–0.86)
2	1.14 (0.89–1.47)	0.76 (0.61–0.96)
3	1.39 (1.09–1.76)	0.93 (0.77–1.11)
4	1.68 (1.27–2.23)	1.13 (0.91–1.40)
5	2.04 (1.42–2.94)	1.37 (1.01–1.85)
6	2.48 (1.56–3.95)	1.66 (1.10–2.49)

Data presented are aHRs (95% CIs). aHRs are adjusted for average number of ineffective drugs received per day, average number of untested drugs received per day, extent and pattern of baseline resistance, previous treatment history, sputum smear result, and extent of disease. Analysis was stratified by country. Initial sputum culture conversion was defined as at least two consecutive negative cultures of sputum samples collected at least 30 days apart. 95% confidence intervals given in parentheses. aHRs in bold are statistically significant.

*Median: 3; range: 0–6.