Table 2.

Risk of Mycobacterium tuberculosis infection after 12 months among household contacts of index patients with tuberculosis by drug resistance profile. Values are prevalence ratio (95% confidence interval) unless stated otherwise

Drug resistance profile	Prevalence of infection* (No (%))	Univariable analysis (n=8630)	Multivariate analysis
			Model 1 (n=7463)†	Model 2 (n=7463)‡	Model 3 (n=7190)§
Pan susceptible	3597 (69.3)	Reference	Reference	Reference	Reference
Mono isoniazid	185 (80.8)	1.17 (1.09 to 1.25)¶	1.16 (1.08 to 1.24)¶	1.14 (1.07 to 1.23)¶	1.15 (1.06 to 1.24)¶
Mono streptomycin	716 (72.2)	1.04 (0.99 to 1.09)	1.03 (0.98 to 1.08)	1.03 (0.98 to 1.08)	1.02 (0.98 to 1.08)
Isoniazid+streptomycin	256 (74.4)	1.08 (1.01 to 1.16)¶	1.06 (0.99 to 1.14)	1.06 (0.99 to 1.14)	1.04 (0.95 to 1.12)
Multidrug resistant	1041 (75.7)	1.08 (1.04 to 1.13)¶	1.08 (1.04 to 1.13)¶	1.08 (1.04 to 1.13)¶	1.11 (1.04 to 1.17)¶
Other	353 (70.3)	1.02 (0.95 to 1.09)	1.04 (0.97 to 1.11)	1.04 (0.97 to 1.11)	1.05 (0.97 to 1.13)

^*Prevalence of the univariable model.

^†Model 1 adjusted for index patient characteristics (age category, HIV status, smoking status, alcohol consumption) and household contact characteristics (age category, self reported diabetes mellitus, number of BCG scars, alcohol consumption, nutritional status, socioeconomic status, use of isoniazid preventive treatment, and previous tuberculosis disease).

^‡Model 2 adjusted for the factors included in model 1 plus characteristics of the index case (presence of cavities on chest radiograph, sputum smear grade, and diagnostic delay).

^§Model 3 adjusted for the factors included in model 2 plus the time until initiation of effective treatment.

^¶Effects that are statistically significant.