Association of Polypharmacy and Bone Mineral Density: A Cross-Sectional Analysis of Geriatric Inpatients in Germany

<b>Background:</b> Osteoporosis is a prevalent metabolic bone disorder characterized by reduced bone mineral density (BMD) and increased fracture risk, particularly among older adults. While individual medications have been implicated in bone loss, the cumulative impact of polypharmacy on skeletal health remains underexplored. <b>Methods:</b> This cross-sectional study included 1155 geriatric inpatients undergoing routine bone mineral density assessment. Medication use, demographic characteristics, and clinical variables were extracted from electronic medical records. BMD at the lumbar spine (L1-L4) and total hip was measured using dual-energy X-ray absorptiometry (DXA). Unadjusted analyses and multivariable linear regression models were used to examine associations between medication use, polypharmacy (defined as the use of ≥5 medications), and BMD, adjusting for age, sex, body mass index, and relevant clinical covariates. <b>Results:</b> The mean age of the study population was 85.0 ± 7.1 years, and 80.1% were female. Polypharmacy was present in 64.5% of patients. In medication-specific analyses, thyroid hormone use was associated with lower lumbar spine BMD (<i>p</i> = 0.032), and concomitant use of diuretics and proton pump inhibitors was associated with lower hip BMD (<i>p</i> = 0.049). Steroid use showed a marginally non-significant correlation with reduced BMD (<i>p</i> = 0.057). Polypharmacy was associated with lower lumbar spine BMD (<i>p</i> = 0.022), whereas no significant association was observed with hip BMD. Increasing age was consistently associated with lower BMD across skeletal sites (<i>p</i> < 0.001). <b>Conclusions:</b> In this geriatric inpatient cohort, polypharmacy and selected medication classes were associated with lower bone mineral density, particularly at the lumbar spine. Given the cross-sectional design, these findings reflect associations rather than causal relationships and may partly capture underlying multimorbidity and clinical complexity. Consideration of medication burden may be relevant when evaluating bone health in older adults. Polypharmacy is increasingly common in older adults and may contribute to bone fragility. In this cohort of 1155 geriatric inpatients, multiple medications and certain drug classes were associated with lower bone mineral density, particularly in the spine. These findings suggest that medication burden should be considered when evaluating osteoporosis risk in aging populations.