The impact of different combinations of body mass index and depressive status on the incidence of sarcopenia in middle-aged and older adults ≥45 years: A retrospective cohort study based on CHARLS follow-up data from 2011 to 2015.

Sarcopenia is a major public health concern among middle-aged and older adults. Although abnormal body mass index (BMI) and depression are recognized as independent risk factors for sarcopenia, longitudinal evidence regarding their combined impact remains limited. This retrospective cohort study utilized data from the China Health and Retirement Longitudinal Study, including the 2011 baseline survey and 2013 and 2015 follow-up surveys. Participants aged ≥ 45 years without baseline sarcopenia were categorized by BMI (overweight: ≥25 kg/m2; non-overweight: <25 kg/m2) and depressive status (Center for Epidemiologic Studies Depression Scale-10 ≥ 10). Cox proportional hazards regression model was used to examine associations with incident sarcopenia (Asian Working Group for Sarcopenia 2019 criteria). Among 7845 participants aged ≥ 45 years without baseline sarcopenia, 1294 cases of sarcopenia occurred during a median 4-year follow-up. Participants were classified into 4 groups based on baseline BMI and depressive status: non-overweight without depression (41.0%), non-overweight with depression (21.0%), overweight without depression (26.3%), and overweight with depression (11.7%). Groups differed significantly in sociodemographic characteristics, lifestyle factors, and chronic disease prevalence (P < .001). In the multivariable Cox analysis (Model 2, adjusted for sociodemographic, lifestyle, and chronic disease factors), compared with the overweight without depression group (reference), the non-overweight with depression group had the highest risk of developing sarcopenia (hazard ratio HR = 2.645, 95% confidence interval CI: 2.221-3.150), followed by the non-overweight without depression group (HR = 2.193, 95% CI: 1.858-2.588) and the overweight with depression group (HR = 1.326, 95% CI: 1.066-1.649). Subgroup analysis showed that this association was particularly significant in individuals aged < 65 years (P for interaction = .001); the non-overweight with depression group had a 3.395-fold higher risk than the reference group (95% CI: 2.713-4.250). Non-overweight with depression was the highest-risk combination for incident sarcopenia in adults ≥ 45 years, particularly those aged < 65 years. Combined assessment of body composition and psychological status may facilitate early identification and targeted intervention.