Volume 8, Number 11—November 2002
THEME ISSUE
Tuberculosis Genotyping
Tuberculosis Genotyping Network, United States
DNA Fingerprinting of Mycobacterium tuberculosis Isolates from Epidemiologically Linked Case Pairs
, Ida M. Onorato*, Barbara A. Ellis*, Jack T. Crawford*, Barbara Schable*, Robert Byers*, J. Steve Kammerer*, and Christopher R. Braden*
Table 3
Logistic regression modela showing factors associated with transmission unconfirmed by DNA fingerprinting in tuberculosis case pairs identified in contact investigations in seven sites, 1996–2000
| Factor | Adjusted odds ratio (95% confidence intervals) | p value |
|---|---|---|
| Smear-negative source case | 2.0 (1.2 to 3.1) | 0.001 |
| Foreign-born secondary case | 3.4 (2.0 to 6.0) | <0.0001 |
| Secondary case <15 yrs | 0.3 (0.2 to 0.8) | 0.01 |
| Secondary case >65 yrs | 1.7 (0.8 to 3.6) | 0.2 |
| Workplace setting | 2.7 (0.9 to 5.7) | 0.08 |
aThe model also included in the multiple logistic regression analysis all levels of the following factors that were not significantly associated with unconfirmed transmission: cavitary disease in source case, race/ethnicity of case pair, and HIV status of secondary case. In the goodness-of-fit test, full model’s p value was 0.885; and the p value for a reduced model containing only the variables with significant associations was 0.725. Thus, both models fit adequately. For the full model, –2 x log likelihood was 564.044; for the reduced model, –2 x log likelihood was 571.469. The difference was distributed as a chi-square variable with 1 degree of freedom. The full model gave a better fit than the reduced model and was retained (p=0.0064, chi square >7.425).