The Prevalence of Frailty and Its Association with Adverse Drug Reactions in Hospitalized Older Adults

Background: The complex interplay between altered pharmacokinetics and pharmacodynamics, greater multimorbidity and polypharmacy, are associated with increased risk of adverse drug reactions (ADR) in older adults. There remains a paucity of data on the association between frailty and ADRs. We aimed to determine the association between frailty and the prevalence, presentation and severity of ADRs among hospitalized older adults. Methods: This was a retrospective, cross-sectional study in an acute care hospital in Singapore. The first 150 older adults admitted from emergency department or outpatient clinic under Geriatric Medicine service in September 2016 were included. We used Clinical Frailty Scale (CFS) to determine frailty status. Probability and severity of ADRs were determined using Naranjo and Hartwig Scale respectively. Results: The prevalence of frailty was 83.3%; mean age and CFS were 89.7 ± 4.0 years, and 6 ± 1.3 respectively. Majority (70%) experienced at least 1 side effect; more than 40% of these ADRs were of mild to moderate in severity. Constipation was the most common ADR (41.3%) and was associated with calcium supplement. ACE-inhibitors, diuretics and anti-platelets were also frequently associated with ADRs in older adults. Frail older adults significantly experienced lesser cardiovascular ADRs but more central nervous system ADRs compared to the non-frail group (P < 0.05). Conclusions: There is a high prevalence of frailty and ADRs in hospitalized older adults, with ADRs mostly mild to moderate in severity. More robust studies to prospectively explore the relationship between frailty and ADRs are required.