TABLE 4.

Linear regression model for log TTP, adjusting for clustering of repeated measures in a single participant, using robust standard errors^a

Log TTP	Coefficient	SE	P	95% CIb
Constantc	2.120	0.016	<0.001	2.089 to 2.151
Day on treatment	0.017d	0.001	<0.001	0.015 to 0.018
Vol (ml)e
6–10	−0.069	0.015	<0.001	−0.098 to −0.040
>10	−0.113	0.017	<0.001	−0.148 to −0.079

^an = 5,372; number of clusters, 439; F (3.438) = 191.52; P < 0.001; R² = 0.2174; root mean squared error (MSE), 0.1655. TTP, time to culture positivity.

^b95% CI, 95% confidence interval.

^cThe constant represents the expected log TTP in the smallest volume category (<6 ml) when the time on treatment is zero.

^dEach day of increase in treatment duration increases the log TTP by 0.017.

^eFor the expected log TPP when the sputum volume changes from <6 ml to a higher volume category, add the corresponding volume coefficient.