OBJECTIVES: This study was conducted to analyze the effect of body weight on mortality in hip fracture patients in Korea.

METHODS: The study was conducted using the sample cohort database of the National Health Insurance Service, which was created by stratifying 2% of the Korean population by sex, age, enrollee classification, insurance premium quintile, and region for all Korean citizens who were enrolled in National Health Insurance and eligible for medical aid in 2006. For 4475 adult hip fracture patients aged 19 and above from 2003 to 2018 who did not experience a hip fracture in the past year and had weight data, we calculated mortality rates by weight group. Adjusted odds ratios(OR) were estimated by comparing lower or higher weight versus normal weight group.

RESULTS: Weight group and mortality were correlated (p<0.001). Among hip fracture patients aged 65 and older, the average mortality rate was 12.89%. The underweight group(BMI <18.5 kg/m2) had a mortality rate of 28.20%, the normal weight group(BMI 18.5-22.9 kg/m2) had a mortality rate of 15.51%, the overweight group(BMI 23.0-24.9 kg/m2) had a mortality rate of 11.73%, and the obese group(BMI ≥25.0 kg/m2) had a mortality rate of 6.48%. The adjusted OR, which was calculated using the normal weight group as the reference group and corrected for gender and age, shows a higher OR in the underweight group(OR: 1.605, 95% CI: 1.152-2.235) and a lower OR in the overweight(OR: 0.830, 95% CI: 0.596-1.154) and obese group(OR: 0.774, 95% CI: 0.553-1.084).

CONCLUSIONS: There is a statistically significant association between body weight and mortality. Mortality among hip fracture patients was higher in the underweight group compared to the normal weight group, and lower in the overweight and obese groups. The study has implications for the importance of weight management after hip fracture.