Table 1 |.
Estimated association among bacterial and patient factors and the rate of secondary cases generated
| Dependent variable: rate of secondary cases | ||||||
|---|---|---|---|---|---|---|
| All isolates with metadata (PP > 0.5), n = 1,263 | Excluding isolates from incarcerated individuals (PP > 0.5), n = 1,092 | All isolates with metadata, n = 1,263 | ||||
| Explanatory variables | Levels | Total | Univariable IRR (CI95, P value) | Multivariable aIRRadJ (CI95, P value) | Multivariable aIRRadJ (CI95, P value) | Multivariable aIRRadJ (CI95, P value) |
| Putative compensatory mutation in rpoA, rpoB and rpoC | 0 | 389 (30.80) | – | – | – | – |
| 1 | 874 (69.20) | 1.68 (1.34–2.12, P < 0.001) | 1.34 (1.05–1.71, P = 0.019) | 1.30 (1.01–1.69, P = 0.046) | 1.37 (1.11–1.70, P = 0.003) | |
| Incarcerated individual | 0 | 1092 (86.46) | – | – | – | – |
| 1 | 171 (13.54) | 2.14 (1.71–2.64, P < 0.001) | 1.42 (1.11–1.81, P = 0.005) | – | 1.51 (1.22–1.87, P < 0.001) | |
| Lineage 2 strain | 0 | 180 (14.25) | – | – | – | – |
| 1 | 1083 (85.75) | 2.75 (1.88–4.23, P < 0.001) | 2.24 (1.48–3.53, P < 0.001) | 2.44 (1.53–4.12, P < 0.001) | 2.64 (1.82–3.98, P < 0.001) | |
| Age | Mean (s.d.) | 38.54 (13.75) | 0.98 (0.97–0.99, P < 0.001) | 0.98 (0.97–0.99, P < 0.001) | 0.98 (0.97–0.99, P < 0.001) | 0.98 (0.97–0.99, P < 0.001) |
| Female sex | 0 | 981 (77.67) | – | – | – | – |
| 1 | 282 (22.33) | 0.67 (0.52–0.86, P = 0.002) | 0.73 (0.55–0.95, P = 0.022) | 0.74 (0.56–0.97, P = 0.033) | 0.96 (0.77–1.19, P = 0.735) | |
| Number of additional drug resistance mutations | Mean (s.d.) | 2.02 (0.68) | 1.18 (1.03–1.36, P = 0.020) | 1.04 (0.87–1.24, P = 0.686) | 1.05 (0.86–1.26, P = 0.647) | 1.00 (0.85–1.16, P = 0.983) |
| Drug resistance profile | MDR | 512 (40.54) | – | – | – | – |
| Pre-XDR | 534 (42.28) | 1.15 (0.93–1.42, P = 0.192) | 0.91 (0.73–1.14, P = 0.423) | 0.94 (0.73–1.22, P = 0.645) | 0.91 (0.75–1.10, P = 0.314) | |
| XDR | 217 (17.18) | 1.25 (0.95–1.61, P = 0.101) | 1.17 (0.88–1.54, P = 0.266) | 1.14 (0.84–1.55, P = 0.396) | 0.98 (0.76–1.25, P = 0.859) | |
| TB diagnosis in the past | 0 | 716 (56.69) | – | – | – | – |
| 1 | 547 (43.31) | 0.99 (0.82–1.19, P = 0.913) | 0.94 (0.77–1.15, P = 0.544) | 0.89 (0.71–1.12, P = 0.341) | 0.95 (0.80–1.13, P = 0.566) | |
a
IRRs were estimated by multivariable Poisson regression adjusting for the presence of putative compensatory mutations, incarceration status, Mtb lineage, patient age, patient sex, number of additional drug resistance mutations, drug resistance profile and TB diagnosis in the past. We corrected for unequal observation time of the isolates by including the isolation time as a category. For the 6-year study period, we included 12 half-year categories.