Table 2. Cox regression model showing adjusted and unadjusted associations between identified variable and rates of positive M. ulcerans culture.
| Variable | Failures (Positive culture) (%) | Follow-up (days) | Rate per 100-person days (95% CI) | Crude hazard ratio (95% CI) | p-value | Adjusted hazard ratio (95% CI) | p-value |
|---|---|---|---|---|---|---|---|
| Gender | |||||||
| Female | 10 (24.4) | 1115 | 9.0 (4.83,16.67) | 1 | 0.97 | 1 | 0.86 |
| Male | 12 (23.5) | 1587 | 7.6 (4.5,14.1) | 1.0 (0.4,2.3) | 0.9 (0.4,2.2) | ||
| Age (years) | |||||||
| 0–15 | 1 (7.1) | 603 | 1.7 (0.2–11.8) | 1 | 0.14 | 1 | 0.07 |
| 16–64 | 9(23.1) | 995 | 9.0 (4.7,17.4) | 4.1 (0.5,32.6) | 4.3 (0.5,34.5) | ||
| ≥65 | 12(30.8) | 1104 | 10.9 (6.2,19.1) | 5.1 (0.7,39.3) | 6.6 (0.8,50.8) | ||
| WHO category of lesion | |||||||
| 1 | 14 (25.9) | 1160 | 12.1 (7.1,20.4) | 1 | 0.29 | - | - |
| 2 | 2 (12.5) | 703 | 2.8 (0.7,11.4) | 0.4 (0.1,1.6) | - | ||
| 3 | 6 (27.3) | 839 | 7.2 (3.2,15.9) | 0.9 (0.4,2.5) | - | ||
| Lesion type | |||||||
| Ulcer | 15(25.0) | 1396 | 2.7 (2.1,3.4) | 0.7 (0.1–5.6) | 0.44 | - | - |
| Nodule | 1 (25.0) | 113 | 3.6 (1.6,8.0) | 1 | - | - | |
| Oedema | 6 (25.0) | 993 | 3.0 (1.6,5.8) | 0.7 (0.1,5.5) | - | - | |
| Plaque | 0 (0.0) | 200 | 0.0 | - | - | - | |
| Lesion site | |||||||
| Upper limb | 9 (30.0) | 755 | 11.9 (6.2,22.9) | 1 | 0.38 | - | - |
| Lower Limb | 13 (21.3) | 1913 | 7.0 (3.9,11.7) | 0.6 (0.3,1.4) | - | - | |
| Head/Trunk | 0 (0.0) | 34 | 0.0 | - | - | - | |
| Immune suppression | |||||||
| No | 21 (26.3) | 2351 | 8.9 (5.8,13.7) | 1 | 0.16 | - | 0.06 |
| Yes | 1 (8.3) | 351 | 2.8 (0.4,20.2) | 0.3 (0.0,2.3) | 0.2 (0,1.6) | ||
| Diabetes | |||||||
| No | 22 (27.2) | 2271 | 9.7 (6.4,14.7) | - | - | - | - |
| Yes | 0 (0.0) | 238 | 0 | - | - | ||
| Antibiotic regimen | |||||||
| RCla* | 9(20.5) | 1517 | 5.9 (3.1,11.4) | 1 | 0.48 | - | - |
| RCp** | 12 (27.9) | 1026 | 11.7 (6.6,20.6) | 1.7 (0.7,4.0) | - | ||
| other | 1 (20.0) | 159 | 6.3 (0.9,44.6) | 1.0 (0.1,7.7) | - | ||
| Weight (kg) | |||||||
| 0–90 | 4 (19.1) | 707 | 5.7 (2.1,15.1) | 1 | 0.71 | - | - |
| ≥ 90 | 2 (25.0) | 251 | 8.0 (2.0,31.9) | 1.3 (0.2,7.3) | - | - | |
| Missing | 16 (25.4) | 1744 | 9.2 (5.6,15.0) | 1.6 (0.5,4.7) | - | - | |
| Duration of symptoms prior to diagnosis | |||||||
| 0–42 | 15 (27.8) | 1593 | 9.4 (5.7,15.6) | 1 | 0.50 | - | - |
| ≥42 | 6 (16.7) | 1030 | 5.8 (2.6,12.0) | 0.6 (0.2,1.6) | - | - | |
| Missing | 1 (50) | 79 | 12.7 (1.8, 89.9) | 1.7 (0.2,12.8) | - | - | |
*Rifampicin + Clarithromycin
**Rifampicin + Ciprofloxacin