Table 2.
Trends in first-line anti-tuberculosis drug resistance by patient treatment category in Botswana’s national anti-tuberculosis DRS, 1995–2008
| 1995–1996
|
1999
|
2002
|
2007–2008
|
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|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|
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| n (%) | 95%CI | n (%) | 95%CI | n (%) | 95%CI | n (%) | 95%CI | P value* | |
| New patients | (n = 430) | (n = 638) | (n = 1182) | (n = 924)† | |||||
| Any first-line drug resistance | 16 (3.7) | 2.2–5.8 | 40 (6.3) | 4.6–8.4 | 123 (10.4) | 4.6–8.4 | 156 (16.9) | 14.6–19.4 | <0.0001 |
| Any INH, RMP, EMB resistance | 10 (2.3) | 1.2–4.1 | 30 (4.7) | 3.3–6.6 | 71 (6.0) | 4.8–7.5 | 82 (8.9) | 7.2–10.8 | <0.0001 |
| Any INH | 7 (1.6) | 0.7–3.2 | 28 (4.4) | 3.0–6.2 | 53 (4.5) | 3.4–5.8 | 70 (7.6)‡ | 6.0–9.4 | <0.0001 |
| Any RMP | 4 (0.9) | 0.3–2.2 | 4 (0.6) | 0.2–1.5 | 24 (2.0) | 1.3–3.0 | 33 (3.6)‡ | 2.5–4.9 | <0.0001 |
| Any EMB | 0 | 0–0.9 | 1 (0.2) | 0–0.8 | 15 (1.3) | 0.7–2.1 | 17 (1.8)‡ | 1.1–2.9 | 0.0001 |
| Any SM§ | 6 (1.4) | 0.6–2.9 | 14 (2.2) | 1.3–3.6 | 82 (6.9) | 5.6–8.5 | 96 (10.6)‡ | 8.7–12.8 | <0.0001 |
| Any PZA | NA | NA | 1 (0.1) | 27¶ | NA | ||||
| Monoresistance | |||||||||
| Any (apart from PZA) | 15 (3.5) | 2.0–5.6 | 34 (5.3) | 3.6–7.3 | 86 (7.3) | 5.9–8.9 | 120 (13.0) | 10.9–15.3 | <0.0001 |
| INH | 6 (1.4) | 0.6–2.9 | 23 (3.6) | 2.4–5.3 | 22 (1.9) | 1.2–2.8 | 35 (3.8) | 2.7–5.2 | 0.09 |
| RMP | 3 (0.7) | 0.2–1.9 | 1 (0.2) | 0–0.8 | 10 (0.8) | 0.4–1.5 | 10 (1.1) | 0.6–1.9 | 0.13 |
| EMB | 0 | 0–0.9 | 0 | 0–0.6 | 2 (0.2) | 0–0.6 | 1 (0.1) | 0–0.5 | NA |
| SM | 6 (1.4) | 0.6–2.9 | 10 (1.6) | 0.8–2.8 | 52 (4.4) | 3.3–5.7 | 74 (8.2) | 6.5–10.1 | <0.0001 |
| PZA | NA | NA | 1 (0.1) | 15¶ | NA | ||||
| Any multidrug resistance** | 1 (0.2) | 0–1.3 | 3 (0.5) | 0.1–1.3 | 10 (0.8) | 0.4–1.5 | 23 (2.5)‡ | 1.6–3.7 | <0.0001 |
| Previously treated patients | (n = 121) | (n = 145) | (n = 106) | (n = 137)† | |||||
| Any first-line drug resistance | 18 (14.9) | 9.3–22.1 | 33 (22.8) | 16.5–30.1 | 24 (22.6) | 15.4–31.3 | 32 (23.4) | 16.8–31.0 | 0.13 |
| Any INH, RMP, EMB resistance | 15 (12.4) | 7.4–19.2 | 30 (20.7) | 14.7–27.9 | 19 (17.9) | 11.5–26.1 | 23 (16.8) | 11.2–23.8 | 0.55 |
| Any INH | 12 (9.9) | 5.5–16.3 | 24 (16.6) | 11.2–23.3 | 15 (14.2) | 8.5–21.8 | 14 (10.2)# | 5.9–16.2 | 0.88 |
| Any RMP | 10 (8.3) | 4.3–14.2 | 19 (13.1) | 8.3–19.4 | 13 (12.3) | 7.0–19.6 | 18 (13.1)# | 8.2–19.6 | 0.3 |
| Any EMB | 6 (5.0) | 2.0–10.0 | 4 (2.8) | 0.9–6.5 | 9 (8.5) | 4.2–15.0 | 9 (6.6)# | 3.3–11.7 | 0.24 |
| Any SM | 10 (8.3) | 4.3–14.3 | 7 (4.8) | 2.1–9.3 | 17 (16.0) | 10.0–24.0 | 16 (11.8)# | 7.1–18.0 | 0.07 |
| Any PZA | NA | NA | 0 | 3¶ | NA | ||||
| Monoresistance | |||||||||
| Any (apart from PZA) | 9 (7.4) | 3.7–13.2 | 18 (12.4) | 7.8–18.6 | 7 (6.6) | 3.0–12.6 | 20 (14.6) | 9.4–21.3 | 0.18 |
| INH | 4 (3.3) | 1.1–7.8 | 9 (6.2) | 3.1–11.1 | 0 | 0–3.4 | 3 (2.2) | 0.6–5.8 | 0.17 |
| RMP | 2 (1.7) | 0.3–5.4 | 6 (4.1) | 1.7–8.4 | 0 | 0–3.4 | 8 (5.8) | 2.7–10.8 | 0.19 |
| EMB | 0 | 0–3.0 | 0 | 0–2.5 | 2 (1.9) | 0.3–6.1 | 0 | 0–2.7 | NA |
| SM | 3 (2.5) | 0.6–6.6 | 3 (2.1) | 0.5–5.5 | 5 (4.7) | 1.7–10.1 | 9 (6.6)† | 3.3–11.8 | 0.05 |
| PZA | NA | NA | 0 | 0¶ | NA | ||||
| Any multidrug resistance** | 7 (5.8) | 2.6–11.1 | 13 (9.0) | 5.1–14.5 | 11 (10.4) | 5.6–17.3 | 9 (6.6)# | 3.3–11.7 | 0.81 |
χ2 test for linear trend.
Missing results: new patients: RMP (n = 1), EMB (n = 3), SM (n = 21); retreatment patients: SM (n = 1).
NTRL results for new patients: any INH resistance (n = 70: low INH resistance [n = 25], high INH resistance [n = 45]); any RMP resistance (n = 35); any EMB resistance (n = 18); any SM resistance (n = 169); any MDR-TB (n = 23).
While SM is no longer considered a first-line drug, for the purposes of reporting the results of this DRS we retained its classification as a first-line drug to allow for comparison of results from the three previous DRSs.
As DSTagainst PZA was performed only on a subset of patient isolates sent to NHLS for first-line EQA and SLD DST (PZA results available for 130 new patients and for 22 retreatment patients), the proportion resistant was not calculated.
NTRL results for retreatment patients: any INH resistance (n =14: low INH resistance [n =4], high INH resistance [n =10]), any RMP resistance (n =18); any EMB resistance (n = 8); any SM resistance (n = 25); any MDR-TB (n = 10).
Defined as resistance to at least INH and RMP, with or without other drug resistance.
DRS =drug resistance survey; CI =confidence interval; INH =isoniazid; RMP =rifampicin; EMB =ethambutol; SM =streptomycin; PZA =pyrazinamide; NA =not available; NTRL = National TB Reference Laboratory; MDR-TB = multidrug-resistant tuberculosis; DST = drug susceptibility testing; NHLS = National Health Laboratory Services; EQA = external quality assurance; SLD = second-line drug.