Gender differences in the association between body mass index and health-related quality of life among adults:a cross-sectional study in Shandong, China.

Background: This study aims to assess the association between body mass index (BMI) and health-related quality of life (HRQOL), and to further explore gender differences in BMI-HRQOL association among adults.

Methods: We used data from the fifth Health Service Survey of Shandong Province, which was part of China's National Health Service Survey (NHSS), a total of 27,257 adults aged 18 and over were interviewed. The HRQOL was measured using the EuroQOL-5 Dimensions (EQ-5D) instrument. One-way ANOVA and Post hoc tests were used to compare EQ-5D utility values and visual analogue scale (VAS) scores between BMI categories. Tobit regression models were used to identify the association between BMI and HRQOL for male and female separately after controlling for influential confounders, and to assess gender differences on the relationship between BMI and HRQOL.

Results: The prevalence of underweight in men and women were 3.2 and 5.3%, respectively, while the prevalence of overweight/obesity in men and women were 35.7 and 34.6%, respectively. Men had higher EQ-5D utility values and VAS scores than women. The mean EQ-5D utility value and VAS score was highest in obese men and normal-weight women, respectively. After controlling potential confounders, being underweight was significantly and negatively associated with lower HRQOL among adults. The relationship between obesity and gender was that in women obesity was negatively and significantly associated with HRQOL, whereas in men this association was positive but not statistically significant. Results of gender by BMI interaction in regression model showed that this difference between men and women in this respect was significant.

Conclusions: The association between BMI and HRQOL differed by gender and the so-called "obesity-HRQOL paradox" phenomenon was verified in male adults. Gender difference should be considered when implementing targeted weight control programs and appropriate interventions to improve HRQOL.