Effects of multimorbidity and polypharmacy on physical function in community-dwelling older adults: A 3-year prospective cohort study from the SONIC

Background: We prospectively examined the effect of baseline multimorbidity and polypharmacy on the physical function of community-dwelling older adults over a three-year period. Methods: The analysis included 1,401 older adults (51.5 % women) who participated in both wave 1 and wave 2 (3-year follow-up) of the Septuagenarians, Octogenarians, and Nonagenarians Investigation with Centenarians (SONIC) study. Grip strength and walking speed were binarized into poor/not poor physical function according to the frailty definition. The number of chronic conditions and the number of prescribed medications were categorized into 3 and 4 groups, respectively. Multivariable logistic regression was used to examine associations between the number of chronic conditions, medication use at baseline, and poor physical function over a three-year period. Results: After adjusting for confounding factors, hyperpolypharmacy (≥ 10 medications) demonstrated associations with weak grip strength (adjusted odds ratio [aOR] = 2.142, 95 % confidence interval [CI] = 1.100–4.171) and slow walking speed (aOR = 1.878, 95 % CI = 1.013–3.483), while co-medication (1–4 medications) was negatively associated with slow walking speed (aOR = 0.688, 95 % CI = 0.480–0.986). There was no significant association between the number of chronic conditions and physical function. Conclusion: The findings suggest that the number of medications can serve as a simple indicator to assess the risk of physical frailty. Given that many older individuals receive multiple medications for extended durations, medical management approaches must consider not only disease-specific treatment outcomes but also prioritize drug therapy while actively avoiding the progression towards frailty and geriatric syndromes.