Obesity Linked to Higher Polypharmacy Risk in Older Adults: Study

A new study published in the Journal of General Internal Medicine showed that one of the main causes of polypharmacy in older persons is obesity. The substantial influence of excess body weight on drug consumption is demonstrated by researchers' estimation that obesity accounts for around one in seven cases of polypharmacy when defined by body mass index (BMI) and one in four cases when defined by waist circumference.

Many of the chronic illnesses that lead to polypharmacy are exacerbated by obesity, although it is unclear how much of an impact obesity has on polypharmacy. This study calculated the percentage of polypharmacy in a nationally representative sample of older persons in the United States that may be attributed to obesity.

Thus, to assess the relationship between obesity and polypharmacy (≥5 prescription drugs) in persons aged ≥65 years with a BMI ≥18.5 kg/m², this cross-sectional study used 2021–2023 NHANES data. Waist circumference or BMI classes were used to characterize obesity. Researchers used t-tests and χ² to compare patient characteristics. After adjusting for age, sex, education, smoking, and alcohol use, logistic regression was used to determine the adjusted relative risk (aRR) of polypharmacy associated with obesity.

The aRR and obesity prevalence among older persons with polypharmacy were then used to determine the Population Attributable Fraction (PAF) of polypharmacy caused by obesity. R (v4.2.3) was used in the study to appropriately account for and weight complicated survey designs. The STROBE reporting requirements were followed in this IRB-exempt study.

1,944 individuals, or 53.2 million older persons (mean age 72.7; 55% female), were examined in the research.

Of them, 70.5% had obesity defined by waist circumference and 38.7% had obesity defined by BMI.

The prevalence of polypharmacy was 41.8% overall (22 million adults), although it was much higher in those with BMI-defined obesity than in those without (51.1% vs. 35.9%; p<0.001).

About 3.3 million older persons were included in the population attributable fraction (PAF) of polypharmacy associated with BMI-defined obesity, which was 14.8%.

Class 1 obesity had a PAF of 4.9%, whereas Classes 2–4 had a PAF of 9.7%.

Additionally, the PAF for obesity defined by waist circumference was much higher at 24.8%, suggesting that central adiposity plays a significant role in polypharmacy in this population.

Overall, up to 25% of occurrences of polypharmacy in older persons are caused by obesity, a significant and controllable factor.

Source:

Chen, A. S., Chetty, A. K., Batsis, J. A., Lipska, K. J., & Hajduk, A. M. (2026). Contribution of obesity to polypharmacy in U.s. older adults. Journal of General Internal Medicine. https://doi.org/10.1007/s11606-026-10458-8