Obesity effects on the health-related quality of life in Japan: Implications from a cross-sectional study.

Objectives: Obesity is a global health problem owing to its association with various diseases, in turn requiring various treatment modalities, including expensive drugs and surgeries. In Japan, the obese population is relatively small, thus the impact of the disease is considered to be smaller than that in other countries. However, the impact of obesity and various comorbidities on health-related quality of life (HRQOL) in Japan remains clear. Methods: A cross-sectional (web-based) survey targeting individuals with obesity in Japan was conducted in this study. The survey employed two kinds of HRQOL questionnaires: the MOS 36-Item Short-Form Health Survey (SF-36) and EuroQoL-5 Dimension (EQ-5D). HRQOL scores were calculated for each body mass index category normal weight, and obese 1-3, classes. The effects of obesity and comorbidities on HRQOL were examined using a mediation analysis. Results: Of the survey respondents, 4279 individuals meeting the eligibility criteria were included in the analysis. HRQOL scores generally showed an inverse U-shaped curve peaking at obese l, over weight. Although comorbidities significantly influenced HRQOL decline, obese 2 or higher demonstrated a significant direct effect on HRQOL. Conclusion: While some findings of this study differ from conventional views in Japan and other countries, the impact of obesity on HRQOL may be consistent with findings in other countries when the mediating effects through comorbidities are considered.