Table 2.

Multivariate Adaptive Regression Spline Model Output for Predictors Time-to-Sputum Conversion in 41 Patients

BF	Number of Patients Affected, n (%)	Coefficient
BF1 = max (0, prior tuberculosis episodes – 0)	41 (100)	–2.154
BF2 = (data on ethionamide MIC present)	32 (78)	3.545
BF3 = max (0, 2.5 – ethionamide MIC)* BF2	15 (37)	–1.490
BF4 = (data on chest X-ray cavities present)	29 (71)	0.676
BF5 = max (0, chest X-ray cavities present – 1)* BF4	14 (34)	–3.023
BF6 = (data on weight present)	39 (95)	6.115

Abbreviations: BF, basis function; MIC, minimum inhibitory concentration.