Association of BMI ‐Adjusted Calf Circumference and Age‐Specific Cutoff Values With In‐Hospital Falls Among Older Adults: A Multicenter Prospective Study

AIM: Calf circumference (CC) is a simple surrogate marker of muscle mass. Body mass index (BMI) adjustment and age-specific cutoffs for low CC have been proposed to optimize its use in clinical practice. This study aimed to clarify the association of BMI-adjusted CC and age-specific cutoffs with in-hospital falls among older adults. METHODS: This study was conducted using data from the Japan Hospital Acquired Complications (J-HAC) project, a multicenter cohort study. In this analysis, we included adults aged ≥ 65 years. CC was measured on admission, and the occurrence of falls was assessed and recorded by medical personnel throughout the hospitalization. BMI adjustment and age-specific cutoffs for low CC were applied based on previous studies. Multivariable logistic regression models were developed to examine the association between in-hospital falls and BMI-adjusted CC and age-specific low CC cutoffs, adjusting for age and comorbidities. RESULTS: A total of 808 patients (mean age 83.7 ± 6.6 years, 57.2% females) were analyzed. In females, higher BMI-adjusted CC was significantly associated with a lower risk of in-hospital falls after adjusting for age and comorbidities (adjusted OR = 0.88, 95% CI: 0.77-0.998). Furthermore, low BMI-adjusted CC, as defined by age-specific cutoff values, was independently associated with an increased fall risk in the multivariable model (adjusted OR = 2.39, 95% CI: 1.03-5.54). In contrast, no significant associations were observed in males regardless of CC adjustment or cutoff criteria. CONCLUSIONS: BMI-adjusted CC and age-specific cutoffs showed a stronger association with in-hospital falls among older females than unadjusted CC. Further validation in diverse populations and outcomes is required to confirm their usefulness.