Frailty prevalence according to the Survey of Health, Ageing and Retirement in Europe-Frailty Instrument (SHARE-FI) definition, and its variables associated, in patients with symptomatic knee osteoarthritis: findings from a cross-sectional study

Background: Frailty is a frequent condition in patients with knee osteoarthritis (KOA). However, there are different constructs on how to define it. Survey of Health, Ageing and Retirement in Europe-Frailty Instrument (SHARE-FI) is one of them. Aim: To assess the prevalence of frailty, according to the SHARE-FI definition in patients with symptomatic KOA, and to establish its associated factors. Methods: Symptomatic KOA patients were evaluated for pain symptoms, quality of life, comorbidities, ongoing drug therapy, and radiological damage. Patients were categorised according to the SHARE-FI definition into frail, pre-frail, and non-frail, and compared to a group of healthy controls associated by age and gender. Results: 170 symptomatic KOA patients (76.5% female, mean age 70.1 years) and 186 healthy controls were included. According to SHARE-FI criteria, 35 patients (20.6%) were categorised frail, 50 (29.4%) pre-frail, and 85 (50%) non-frail. The prevalence of frail or pre-frail subjects was statistically significantly higher in patients with symptomatic KOA. Stratifying the patients according to the frailty categories, frail subjects showed significantly higher mean values of pain. The results from logistic regression analysis revealed that polypharmacy (p = 0.003), pain (p = 0.016) and comorbidities (p = 0.035) were the variables independently associated with frailty in symptomatic KOA. Discussion: Frailty or pre-frailty, defined by SHARE-FI, is common in symptomatic KOA. The main factors associated with frailty were polypharmacy, pain and comorbidity burden. Conclusions: SHARE-FI can represent an useful tool to define frailty in symptomatic KOA.