| Patient demographics (n=105) | |||||
| Sex | 59 males (56%) | 46 female (44%) | |||
| Age years | Median (range) 33 (17–74) | Mean±sd 35.7±12.1 | |||
| Ethnicity | 30 Black African/Caribbean (29.1%) | 53 Indian/Pakistani Asian (50%) | 15 Asian other (14.6%) | 3 mixed race (2.9%) | 4 White (3.9%) |
| Smoking habit | 76 never-smoked (72.4%) | 8 ex-smokers/recently stopped (7.6%) | 19 current smokers (18.1%) | 2 chewing tobacco (1.9%) | |
| Alcohol consumption | 93 non-drinkers (88.6%) | 12 drinkers (11.4%) | Mean±sd 8.8±11.5 units per week | Median 4.0 units per week | |
| Tuberculosis drugs | 97 standard chemotherapy (92.4%) | 8 chemoprophylaxis (7.6%) | |||
| Other prescribed drugs | 3 possible drug effect on isoniazid metabolism (2.9%) | 35 unlikely drug effect on isoniazid metabolism (33.3%) | 67 none prescribed (63.8%) | ||
| Recreational drug use (n=98) | 2 reported (2%) | 96 not reported (98%) | |||
| Urine colour change at different time-points after final isoniazid dose | |||||
| Time from last dose of isoniazid | Urine samples tested | Purple (positive) | Blue (positive) | Green (intermediate) | Yellow (negative) |
| ≤12 h | 99 | 75 (76) | 24 (24) | 0 | 0 |
| 24 h | 105 | 17 (16) | 69 (66) | 18 (17) | 1 (1) |
| 48 h | 105 | 0 | 5 (5) | 84 (80) | 16 (15) |
| 72 h | 104 | 0 | 0 | 14 (13) | 90 (87) |
Data are presented as n or n (%), unless otherwise stated. #: rifampicin and vitamin B6 ceased 12 h before first sample.