Baseline characteristics based on tub bathing frequency
|
Tub bathing frequency | ≤2 times/week | 3–4 times/week | Almost daily or every day | P value* |
| Number at risk | 1911 | 6547 | 21 618 | |
| Age (years) | 50.0 | 49.2 | 49.6 | 0.01 |
| Women (%) | 44.3 | 50.2 | 53.6 | <0.01 |
| Current drinker (%) | 34.3 | 39.9 | 41.6 | <0.01 |
| Current smoker (%) | 32.2 | 29.9 | 29.0 | <0.01 |
| Leisure-time sports ≥1 time/week (%) | 10.8 | 14.2 | 15.4 | <0.01 |
| Body mass index ≥25 (%) | 25.2 | 26.8 | 25.1 | 0.88 |
| Junior high school education (%) | 63.3 | 54.2 | 47.3 | <0.01 |
| High school education (%) | 23.3 | 32.1 | 38.8 | <0.01 |
| University or higher education (%) | 11.6 | 12.4 | 12.4 | 0.22 |
| Office worker (%) | 23.9 | 31.4 | 32.4 | <0.01 |
| Manual labour worker (%) | 60.8 | 55.4 | 55.0 | <0.01 |
| Not employed (%) | 15.3 | 13.2 | 12.6 | <0.01 |
| Average sleep duration (hours/day) | 7.6 | 7.4 | 7.3 | <0.01 |
| High perceived mental stress (%) | 24.4 | 24.7 | 24.3 | 0.93 |
| High life enjoyment (%) | 18.4 | 17.7 | 20.2 | 0.05 |
| History of hypertension (%) | 15.9 | 16.3 | 14.6 | 0.10 |
| Medication use for hypertension (%) | 13.0 | 12.9 | 11.9 | 0.16 |
| History of diabetes mellitus (%) | 5.4 | 4.8 | 3.7 | <0.01 |
| Medication use for diabetes mellitus (%) | 2.5 | 1.7 | 1.3 | <0.01 |
| Medication use for hypercholesterolaemia (%) | 2.3 | 2.2 | 2.2 | 0.76 |
| Vegetable intake (g/day) | 156.4 | 173.7 | 190.0 | <0.01 |
| Fruit intake (g/day) | 105.7 | 117.5 | 124.7 | <0.01 |
| Fish intake (g/day) | 49.3 | 51.3 | 57.9 | <0.01 |
| Soybean intake (g/day) | 36.9 | 37.2 | 38.8 | <0.01 |
*The overall difference across the tub bathing frequency was tested using the multiple linear regression for continuous variables and logistic regression for categorical variables, adjusting for age and sex.