Objectives: To determine the association between osteoarthritis (OA), rheumatoid arthritis (RA) and frailty and to determine whether co-morbidities interact with OA and RA to further increase the likelihood of frailty.
Methods: Participants of the UK Biobank aged 40-69 years at baseline were included. Demographic, lifestyle, and clinical data were collected at baseline, and follow-up in a subset. Frailty was assessed using a frailty index (FI) (continuous) and a modified frailty phenotype (robust, pre-frail, frail). The association between RA and OA and frailty at baseline and follow up, was assessed using multiple regression models. We looked at whether co-morbidities, including cardiovascular disease, diabetes, chronic obstructive pulmonary disease and depression, interacted additively with OA and RA to increase the likelihood of frailty.
Results: 457,561 participants contributed data. Those with (versus without) RA (n=4,894), and OA (n=35,884), respectively were more likely to be frail, adjusted relative risk ratio (95%CI) 10.7 (9.7, 11.7) and 3.4 (3.3, 3.6), and were more likely to have a higher FI at baseline. There was evidence of additive interaction, between RA, OA, and common co-morbidities increasing the occurrence of prevalent frailty. Among 25,163 participants included in longitudinal analysis, people with RA (n=202) and OA (n=1,811), at baseline had an increased adjusted frailty incidence rate ratio, 2.8 (1.7, 4.6) and 1.7 (1.3, 2.1) respectively and also a higher FI during follow up.
Conclusion: People with RA and OA are more likely to have, or develop, frailty. Common comorbidities interact with OA and RA to further increase the likelihood of frailty.