High | Twice daily or more | 12 | 17 (2) | 1.05 (0.55 to 1.55) |
Medium high | More than once daily up to twice daily | 10 | 20 (2) | 0.68 (0.14 to 1.22) |
Medium low | More than four times weekly up to once daily | 16 | 6 (1) | 0.65 (0.23 to 1.07) |
Low | ‘Very little’ — up to four times weekly | 17 | 6 (1) | 0.67 (0.19 to 1.15) |
Unsurea | Undefined | 6 | 33 (2) | – |