Background Frailty is a complex geriatric syndrome resulting in decreased physiological reserves in older people. It is very prevalent in nursing homes, as well as it is underprescription of recommended medications in this population. However, little is known about the relationship or interaction between these two entities.

Purpose The aim of this study is to examine the prevalence of underprescription in a nursing home population according to their frailty status.

Material and methods Cross-sectional analysis of baseline data of a concurrent cohort study in participants older than 65 years, resident in two nursing homes. Three frailty measures were used: The Fried frailty criteria, the Frailty Index (FI) of Rockwood and the FRAIL-NH. Underprescription was assessed using the last version of the Screening Tool to Alert to Right Treatments (START) criteria.

Results One hundred and ten individuals were included in the study. Mean age: 86.3 (SD 7.3), 71.8% females. Most of the residents had high rates of functional and cognitive impairment, multimorbidity and malnutrition. The prevalence of frailty according to different scales was: Rockwood’s FI: 71.8%, FRAIL-NH: 42.7% and Fried criteria: 36.4%. The prevalence of underprescription was, in non-frail vs frail individuals: 50% vs 87.5% according to Fried criteria (p=0.013); 48.4% vs 65.8% according to Rockwood’s FI (p=0.092), and 60.3% vs 61.7% according FRAIL-NH scale (p=0.883). The most prevalent criteria were the omission of anabolic or antiresorptive skeletal agents in osteoporosis and/or fragility fractures (26, 23.6%), calcium and vitamin D supplements with osteoporosis and/or fragility fractures (21, 19.1%), angiotensin converting enzyme inhibitor with chronic heart failure/ischaemic heart disease (10, 9.1%) and appropriate β-blocker with stable systolic heart failure (10, 9.1%).

Conclusion There is a significant heterogeneity in the prevalence of underprescription in frail and robust older adults in nursing homes depending on the definition of frailty used, and a statistically significant difference has only been observed with the Fried criteria, with higher rates of underprescription in frail participants. The underlying concepts of the different definitions of frailty could have implications for the assessment of underprescription in frail older adults, and for what should be considered inappropriate prescription and prescribing omissions in this population.

References and/or Acknowledgements Special thanks to Navarrabiomed for their support

No conflict of interest