Table 1. Characteristics of the study population.
| Xpert- or culture-confirmed RIF resistant TB (n=71) | Culture-confirmed RIF sensitive TB (n=98) | Culture-negative Xpert positive (n=64) | Culture negative Xpert negative (n=119) | P value | |
|---|---|---|---|---|---|
| Age, median years (IQR) | 33 (27-43) | 35 (28-43) | 37 (29-45) | 39 (31-46) | 0.04 |
| Female (%) | 34 (47.9) | 30 (30.6) | 22 (34.4) | 50 (42.0) | 0.03 |
| HIV Infection | 47 (69.1) | 61 (62.2) | 41 (64.1) | 89 (74.8) | 0.21 |
| CD4+ T-cell count/mm3, median (IQR) | 189 (100-374) | 195 (105-390) | 211 (90-253) | 249 (89-372) | 0.79 |
| On ART (%) | 41 (89.1) | 36 (60.0) | 38 (92.7) | 68 (76.4) | <0.001 |
| Retreatment TB Type (%) | <0.001 | ||||
| Treatment failure (%) | 21 (29.6) | 5 (5.1) | 10 (15.6) | 30 (25.2) | |
| “Category I” (%)* | 10 (47.6) | 1 (20.0) | 6 (60.0) | 19 (63.3) | |
| “Category II” (%)† | 11 (52.4) | 4 (80.0) | 4 (40.0) | 11 (36.7) | |
| Late smear conversion (%) | 16 (22.5) | 4 (4.1) | 44 (68.8) | 22 (18.5) | |
| Relapse (%) | 29 (40.9) | 64 (65.3) | 7 (10.9) | 52 (43.7) | |
| Early (1-12 months) (%) | 14 (48.3) | 8 (12.5) | 0 (0.0) | 12 (23.1) | <0.001 |
| Late (>12 months) (%) | 15 (51.7) | 56 (87.5) | 7 (100) | 40 (76.9) | |
| Default (%) | 4 (5.6) | 21 (21.4) | 3 (4.7) | 9 (7.6) | |
| Other (%) | 1 (1.4) | 4 (4.1) | 0 (0.0) | 6 (5.0) | |
| Xpert cycle threshold, median (IQR) | 19.7 (16.9-24.1) | 21.3 (18.3-25.2) | 27.1 (24.5-30.3) | N/A | <0.001 |
| Number of Prior Rx Courses | <0.001 | ||||
| None (%) | 20 (28.2) | 4 (4.1) | 45 (70.3) | 29 (24.4) | |
| One (%) | 35 (49.3) | 67 (68.4) | 13 (20.3) | 62 (52.1) | |
| Two or more (%) | 16 (22.5) | 27 (27.6) | 6 (9.4) | 28 (25.3) | |
| Infectious Period,§ median days (IQR), p<0.001 | 269 (161-458) | 86 (44-147) | 72 (45-143) | 100 (45-326) | <0.001 |
| Number of symptoms at presentation ‖ | 0.04 | ||||
| 1 | 0 (0.0) | 7 (7.1) | 4 (6.3) | 15 (0.8) | |
| 2 | 14 (19.7) | 19 (19.4) | 13 (20.3) | 15 (12.6) | |
| 3 | 24 (33.8) | 41 (41.8) | 23 (35.9) | 30 (25.2) | |
| 4 | 30 (42.3) | 27 (27.6) | 19 (29.7) | 31 (26.1) | |
| 5 | 1 (1.4) | 4 (4.1) | 5 (7.8) | 5 (4.2) | |
| Body Mass Index (%) | 0.06 | ||||
| <18 | 25 (38.5) | 25 (26.0) | 11 (18.3) | 25 (22.1) | |
| 18-25 | 40 (61.5) | 97 (69.8) | 47 (78.3) | 80 (70.8) | |
| >25 | 0 (0.0) | 4 (4.2) | 2 (3.3) | 8 (7.1) | |
| Contact with known TB patient | 31 (43.7) | 29 (30.0) | 13 (20.6) | 26 (21.9) | <0.01 |
| Travelled to another country | 22 (31.0) | 33 (33.7) | 21 (32.8) | 43 (36.1) | 0.90 |
| Travelled to South Africa | 15 (21.1) | 19 (19.4) | 13 (20.3) | 25 (21.0) | 0.99 |
| Hospitalized in the past 5 years | 16 (22.5) | 27 (27.6) | 19 (29.7) | 28 (23.5) | 0.71 |
| Prison in the past 5 years | 2 (2.8) | 2 (2.0) | 2 (3.1) | 5 (4.2) | 0.84 |
| Household income (quartiles) | 0.88 | ||||
| Lowest ($0-100/month) | 21 (29.6) | 27 (27.6) | 15 (23.4) | 34 (29.1) | |
| Second ($106-200/month) | 23 (32.4) | 25 (25.5) | 19 (29.7) | 37 (31.6) | |
| Third ($220-300/month) | 11 (15.5) | 22 (22.5) | 13 (20.3) | 16 (13.7) | |
| Highest ($328-5000/month) | 16 (22.5) | 324 (24.5) | 17 (26.6) | 30 (25.6) |
The denominator for each characteristic excludes missing or unknown values. Categorical data was analysed using Chi-square and Fisher's exact tests; continuous data was analysed using Kruskal–Wallis equality-of-populations rank test.
*
Category I refers to standard first-line TB treatment (2HRZE/4HR)
†
Category II refers to the retreatment regimen with first-line drugs (2HRZES/1HRZE/5HRE)
‡
Late smear conversion was defined as AFB sputum smear-positivity at month three during treatment with first-line drugs
§
Days symptomatic prior to initiation of appropriate anti-TB medications.
‖
Assessed symptoms included cough, fever, night sweats, and weight loss.