Table 5. The Comparisons of Metabolic Parameters Among Three Groups Divided by the Frequency of Hot-Tub Bathing.
| Frequency of hot-tub bathing (per week) | ≥ 4 (Group 1) | < 4, ≥ 1 (Group 2) | < 1 (Group 3) | P |
|---|---|---|---|---|
| N (gender: M/F) | 693 (386/307) | 415 (235/180) | 189 (92/97) | 0.163 |
| Age (years) | 67.5 ± 13.2 | 68.0 ± 13.6 | 62.3 ± 13.7 | < 0.001 |
| Body weight (kg) | 66.2 ± 15.6 | 67.1 ± 16.9 | 70.0 ± 18.6 | 0.026 |
| BMI (kg/m2) | 25.5 ± 5.0 | 26.0 ± 5.4 | 26.7 ± 6.0 | 0.025 |
| Waist circumference (cm) | 92 ± 14 | 94 ± 16 | 101 ± 17 | 0.012 |
| Systolic blood pressure (mm Hg) | 133 ± 15 | 132± 18 | 134 ±17 | 0.412 |
| Diastolic blood pressure (mm Hg) | 73 ± 12 | 75 ± 12 | 77 ± 13 | 0.001 |
| Plasma glucose (mg/dL) | 153 ± 50 | 160 ± 54 | 162 ± 62 | 0.057 |
| HbA1c (%) | 7.10 ± 0.97 | 7.20 ± 1.11 | 7.36 ± 1.67 | 0.012 |
| AST (IU/L) | 27 ± 14 | 25 ± 12 | 28 ± 32 | 0.090 |
| ALT (IU/L) | 28 ± 21 | 26 ± 22 | 29 ± 30 | 0.147 |
| γGTP (IU/L) | 41 ± 47 | 40 ± 49 | 56 ± 144 | 0.048 |
| Total cholesterol (mg/dL) | 185 ± 33 | 183 ± 35 | 190 ± 42 | 0.179 |
| HDL-C (mg/dL) | 55 ± 15 | 56 ± 16 | 55 ± 16 | 0.855 |
| LDL-C (mg/dL) | 102 ± 32 | 106 ± 36 | 112 ± 36 | 0.431 |
| Triglyceride (mg/dL) | 148 ± 125 | 183 ± 35 | 190 ± 42 | 0.275 |
| eGFR (mL/min/1.73 m2) | 70 ± 22 | 69 ± 21 | 69 ± 24 | 0.424 |
Comparisons of variables between the three groups were performed by one-way analysis of variance (ANOVA) and Tukey’s multiple comparison test. Data are expressed as mean ± SD. BMI: body mass index; HbA1c: hemoglobin A1c; AST: aspartate aminotransferase; ALT: alanine aminotransferase; γGTP: γ-glutamyl transferase; HDL-C: high-density lipoprotein-cholesterol; LDL-C: low-density lipoprotein-cholesterol; eGFR: estimated glomerular filtration rate; SD: standard deviation; M: male; F: female.