Underweight Status is Associated with Prevalent Anemia in Postmenopausal Women with Osteoporotic Vertebral...

The association between body mass index (BMI) and anemia remains inconsistent across populations. This study aimed to examine the association between BMI categories and prevalent anemia in postmenopausal women with osteoporotic vertebral compression fractures (OVCFs).

In this single-center, hospital-based cross-sectional study, 351 postmenopausal women with OVCFs admitted to a tertiary hospital in East China between July 2018 and June 2024 were included. BMI was categorized according to Chinese criteria. Anemia was defined as hemoglobin <120 g/L. Associations between BMI, hemoglobin levels, and prevalent anemia were assessed using correlation analyses, multiple linear regression, and sequential multivariable logistic regression models.

Overall, 156 patients (44.4%) had anemia. The prevalence of anemia was highest in the underweight group (77.1%), followed by the normal-weight (42.9%), overweight (33.3%), and obese (31.3%) groups. Hemoglobin levels increased across BMI categories, and BMI was positively correlated with hemoglobin levels (r_s = 0.317, P < 0.001). In multivariable analyses, underweight status was associated with lower hemoglobin levels and higher odds of prevalent anemia compared with normal weight. In the fully adjusted logistic model, underweight status remained significantly associated with prevalent anemia (aOR = 3.738, 95% CI: 1.648-8.483, P = 0.002), whereas overweight and obesity were not independently associated with anemia.

In postmenopausal women hospitalized with OVCFs, underweight status was associated with lower hemoglobin levels and higher odds of prevalent anemia, while overweight and obesity were not independently associated with anemia. Underweight status may serve as a simple clinical flag prompting hemoglobin and nutritional assessment in this clinically vulnerable fracture population.