Table 3

Multivariable-adjusted HRs and 95% CIs for incident CVD according to tub bathing frequency after stratification by subjective tub water temperature

Tub bathing frequency≤2 times/week3–4 times/weekAlmost daily or every dayP value for trend
Lukewarm tub water
 Participants3278002596
 Person-years541713 72746 096
 Total CVD, n3872212
 Multivariable-adjusted HR (95% CI)*1 (reference)0.84 (0.56 to 1.25)0.78 (0.55 to 1.11)0.357
 CHD, n71228
 Multivariable-adjusted HR (95% CI)*1 (reference)0.91 (0.34 to 2.42)0.67 (0.27 to 1.63)0.365
 Total stroke, n3160184
 Multivariable-adjusted HR (95% CI)*1 (reference)0.83 (0.54 to 1.29)0.81 (0.55 to 1.20)0.582
Warm tub water
 Participants1289465914 819
 Person-years22 25782 253268 138
 Total CVD, n122335965
 Multivariable-adjusted HR (95% CI)*1 (reference)0.83 (0.67 to 1.02)0.74 (0.61 to 0.90)0.008
 CHD, n2148147
 Multivariable-adjusted HR (95% CI)*1 (reference)0.70 (0.42 to 1.18)0.68 (0.42 to 1.08)0.330
 Total strokes, n101287818
 Multivariable-adjusted HR(95% CI)*1 (reference)0.86 (0.68 to 1.08)0.75 (0.61 to 0.93)0.017
Hot tub water
 Participants28710804171
 Person-years499418 98075 670
 Total CVD, n3272245
 Multivariable-adjusted HR (95% CI)*1 (reference)0.74 (0.48 to 1.14)0.65 (0.44 to 0.95)0.056
 CHD, n71839
 Multivariable-adjusted HR (95% CI)*1 (reference)0.94 (0.36 to 2.41)0.51 (0.21 to 1.22)0.049
 Total strokes, n2554206
 Multivariable-adjusted HR (95% CI)*1 (reference)0.70 (0.43 to 1.14)0.68 (0.44 to 1.05)0.240

  • *Adjusted for age; sex; 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.

  • CHD, coronary heart disease; CVD, cardiovascular disease.