Table 2.
Factors Associated With Xpert False Positivity in New and Retreatment Cases
| New TB Patients (n = 461) | Univariate Analysis |
Multivariate Logistic Regression |
||||
|---|---|---|---|---|---|---|
| True-Positive Xpert (n = 421) | False-Positive Xpert (n = 40) | OR (95% CI) | P Value | Adjusted OR (95% CI) | P Value | |
| Demographic variables | ||||||
| Age, y, median (IQR) | 33 (27–43) | 32 (25–44) | 1.00 (.97–1.02) | .780 | … | … |
| Female, No. (%) | 187/414 (45) | 25/40 (63) | 2.02 (1.04–3.95) | .039 | … | … |
| Smoker, No. (%) | 125/347 (36) | 13/30 (43) | 1.36 (.64–2.89) | .427 | … | … |
| Clinical variables | ||||||
| HIV-infected, No. (%) | 162/404 (58) | 21/39 (50) | 1.74 (.90–3.37) | .099 | … | … |
| Xpert information | ||||||
| TB-specific CT values, median (IQR) | 21.50 (17.72–26.10) | 28.03 (21.20–32.23) | 1.14 (1.07–1.21) | <.001 | 1.14 (1.08–1.21) | <.001 |
| Retreatment Patients (n = 321) | True-Positive Xpert (n = 276) | False-Positive Xpert (n = 45) | OR (95% CI) | P Value | Adjusted OR (95% CI) | P Value |
| Demographic variables | ||||||
| Age, y, median (IQR) | 37 (30–45) | 41 (21–48) | 1.03 (1–1.07) | .030 | … | … |
| Female, No. (%) | 108/274 (39) | 15/42 (36) | 1.17 (.60–2.30) | .647 | … | … |
| Smoker, No. (%) | 100/229 (44) | 18/32 (56) | 1.66 (.79–3.50) | .184 | … | … |
| Clinical variables | ||||||
| HIV-infected, No. (%) | 122/273 (45) | 20/43 (47) | 1.08 (.57–2.05) | .823 | … | … |
| Previous TB treatment not completed, No. (%) | 55/239 (23) | 26/39 (26) | 1.15 (.53–2.51) | .719 | … | … |
| Years since previous TB treatment stopped or completed, median (IQR) | 2 (0–5) | 1 (0–1) | 0.92 (.85–.99) | .033 | 0.91 (.84–.99) | .048 |
| Xpert information | ||||||
| TB-specific CT values, median (IQR) | 20.30 (16.71–25.05) | 29.28 (26.18–30.60) | 1.27 (1.18–1.37) | <.001 | 1.25 (1.15–1.35) | <.001 |
Versions of this table for all patients (Supplementary Table 1) or restricted to the subset of patients with chest radiographic data (Supplementary Table 2) are provided in the Supplementary Data.
Abbreviations: CI, confidence interval; CT, cycle threshold; HIV, human immunodeficiency virus; IQR, interquartile range; OR, odds ratio; TB, tuberculosis.