Associations between Number of Different Medications per Day and Physical Function in Icelandic Community Dwelling Older Adults

Abstract: The number of different medications per day has been linked to reduced physical function in older adults. The aim of the present study was to investigate the associations between medication count and physical function in older adults with particular consideration of the potentially mediating effects of physical activity, skeletal muscle mass, cognitive function and the body’s fluid balance. This was a cross-sectional study conducted in 2022 including 69 community dwelling participants (age = 82.5 ± 6.5 years) who were service users provided by a nursing home in Reykjavik, Iceland. Each participant attended one session of ~60 min with the study staff for doing physical tests (anthropometrics, muscle strength, physical function) and answering questionnaires on lifestyle and health. Among the 46 women and 23 men, the prevalence of sarcopenia was 60.3%, and 52.2% of participants reported using ≥5 medications/day. When adjusted for sex and age, medication count was significantly associated with lower grip strength (B = –0.46 kg, P = 0.039), lower chair-rise test score (B = –0.15, P = 0.004) and lower short-physical-performance-battery score (B = –0.23, P = 0.040). Further adjustment for skeletal muscle mass and cognitive function only slightly attenuated the associations. However, adjusting for physical activity and extracellular/total body water ratio reduced the effect sizes by approximately 35–65%, and most associations were no longer statistically significant. In this specific, highly frail group of older adults there was a high prevalence of sarcopenia, low muscular strength and low physical function. The number of medications per day was found to be significantly associated with low muscle strength and poor physical function. Our study further indicates that the associations between the number of different medications per day and strength and physical function are partly mediated by low physical activity and high extracellular/total body water ratio in participants with higher daily medication use.