HRs and 95% CIs for incident CVD according to tub bathing frequency
| Tub bathing frequency | ≤2 times/week | 3–4 times/week | Almost daily or every day | P value for trend |
| Participants | 1911 | 6547 | 21 618 | |
| Person-years | 32 787 | 115 111 | 390 475 | |
| Total CVD, n | 193 | 479 | 1425 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 0.76 (0.64 to 0.90) | 0.65 (0.56 to 0.76) | <0.001 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 0.80 (0.67 to 0.94) | 0.72 (0.62 to 0.84) | <0.001 |
| Coronary heart disease, n | 35 | 78 | 215 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 0.71 (0.47 to 1.05) | 0.57 (0.40 to 0.82) | 0.007 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 0.75 (0.50 to 1.12) | 0.65 (0.45 to 0.94) | 0.065 |
| Myocardial infarction, n | 28 | 60 | 187 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 0.68 (0.43 to 1.06) | 0.62 (0.42 to 0.93) | 0.103 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 0.68 (0.43 to 1.07) | 0.67 (0.44 to 1.00) | 0.274 |
| Sudden cardiac death <1 hour, n | 7 | 18 | 28 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 0.83 (0.35 to 2.00) | 0.37 (0.16 to 0.85) | 0.004 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 1.19 (0.48 to 2.95) | 0.57 (0.24 to 1.37) | 0.061 |
| Total strokes, n | 158 | 401 | 1210 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 0.77 (0.64 to 0.93) | 0.67 (0.57 to 0.79) | <0.001 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 0.81 (0.67 to 0.97) | 0.74 (0.62 to 0.87) | 0.005 |
| Cerebral infarction, n | 91 | 203 | 697 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 0.69 (0.54 to 0.89) | 0.67 (0.54 to 0.84) | 0.046 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 0.74 (0.57 to 0.94) | 0.77 (0.62 to 0.97) | 0.467 |
| Intracerebral haemorrhage, n | 54 | 140 | 316 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 0.79 (0.57 to 1.08) | 0.52 (0.39 to 0.69) | <0.001 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 0.82 (0.60 to 1.13) | 0.54 (0.40 to 0.73) | <0.001 |
| Subarachnoid haemorrhage, n | 12 | 52 | 191 | |
| Age-adjusted and sex-adjusted HR (95% CI) | 1 (reference) | 1.22 (0.65 to 2.29) | 1.30 (0.72 to 2.32) | 0.274 |
| Multivariable-adjusted HR (95% CI)* | 1 (reference) | 1.24 (0.66 to 2.33) | 1.35 (0.75 to 2.44) | 0.224 |
*Further adjusted for history of hypertension, diabetes and hypercholesterolaemia; body mass index; alcohol intake; smoking status; physical exercise status; job status; education; sleep duration; perceived stress; life enjoyment; intakes of vegetables, fruit, fish and soybeans; and public health centre area.
CVD, cardiovascular disease.