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Habitual tub bathing and risks of incident coronary heart disease and stroke
  1. Tomohiko Ukai1,2,
  2. Hiroyasu Iso2,3,
  3. Kazumasa Yamagishi3,
  4. Isao Saito4,
  5. Yoshihiro Kokubo5,
  6. Hiroshi Yatsuya6,
  7. Isao Muraki2,
  8. Ehab S Eshak2,7,
  9. Norie Sawada8,
  10. Shoichiro Tsugane8
  1. 1Division of Public Health, Osaka Prefectural Institute of Public Health, Osaka, Osaka, Japan
  2. 2Public Health, Department of Social and Environmental Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
  3. 3Department of Public Health Medicine, Faculty of Medicine, and Health Services Research and Development Center, University of Tsukuba, Tsukuba, Ibaraki, Japan
  4. 4Department of Public Health and Epidemiology, Faculty of Medicine, Oita University, Yufu, Oita, Japan
  5. 5Department of Preventive Cardiology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
  6. 6Department of Public Health, Fujita Health University, School of Medicine, Toyoake, Aichi, Japan
  7. 7Department of Public Health and Preventive Medicine, Faculty of Medicine, Minia University, Minia, Egypt
  8. 8Epidemiology and Preventive Group, Center for Public Health Sciences, National Cancer Center, Chuo-ku, Tokyo, Japan
  1. Correspondence to Professor Hiroyasu Iso, Public Health, Department of Social and Environmental Medicine, Osaka University Graduate School of Medicine, Suita-shi 567-0881, Japan; iso{at}


Objective Tub bathing is considered to have a preventive effect against cardiovascular disease (CVD) by improving haemodynamic function. However, no prospective studies have investigated the long-term effects of tub bathing with regard to CVD risk.

Methods A total of 30 076 participants aged 40–59 years with no history of CVD or cancer were followed up from 1990 to 2009. Participants were classified by bathing frequency: zero to two times/week, three to four times/week and almost every day. The HRs of incident CVD were estimated using Cox proportional hazards models after adjusting for traditional CVD risk factors and selected dietary factors.

Results During 538 373 person-years of follow-up, we documented a total of 2097 incident cases of CVD, comprising 328 coronary heart diseases (CHDs) (275 myocardial infarctions and 53 sudden cardiac deaths) and 1769 strokes (991 cerebral infarctions, 510 intracerebral haemorrhages, 255 subarachnoid haemorrhages and 13 unclassified strokes). The multivariable HRs (95% CIs) for almost daily or every day versus zero to two times/week were 0.72 (0.62 to 0.84, trend p<0.001) for total CVD; 0.65 (0.45 to 0.94, trend p=0.065) for CHD; 0.74 (0.62 to 0.87, trend p=0.005) for total stroke; 0.77 (0.62 to 0.97, trend p=0.467) for cerebral infarction; and 0.54 (0.40 to 0.73, trend p<0.001) for intracerebral haemorrhage. No associations were observed between tub bathing frequency and risk of sudden cardiac death or subarachnoid haemorrhage.

Conclusion The frequency of tub bathing was inversely associated with the risk of CVD among middle-aged Japanese.

  • cardiac risk factors and prevention
  • acute myocardial infarction
  • stroke

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  • Contributors TU conceived the idea for the study. TU, HI, KY, IS, YK, HY, IM, NS and ST collated data for the study. TU, HI and ESE analysed the data. TU wrote the first draft. HI, KY, IS, YK, HY, IM, ESE, NS and ST provided revisions to the first draft. All authors approved the final draft.

  • Funding This work was supported by the National Cancer Center Research and Development Fund (since 2011) and a Grant-in-Aid for Cancer Research from the Ministry of Health, Labour and Welfare of Japan (from 1989 to 2010).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The institutional human ethics review boards of Osaka university and the National cancer center Approved the study. Written informed consent was obtained from participants.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to containing information that could compromise research participant consent.

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