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New findings show patients with osteoarthritis and rheumatoid arthritis share comorbidities that contribute to an increased likelihood of frailty, especially in older populations.
The investigative team, led by Michael J. Cook, defined frailty as a clinical state associated with dysregulation in various physiological systems and loss of homeostatic capacity.
This was linked to increased risk of adverse health outcomes such as morbidity, disability and death.
Many of the characterizations of frailty had been associated with osteoarthritis and rheumatoid arthritis in past studies, though they remained few and far between.
Both osteoarthritis and rheumatoid arthritis were linked to a myriad of comorbid conditions such as hypertension, coronary heart disease (CHD), chronic obstructive pulmonary disease (COPD) diabetes, depression, and more.
Cook and colleagues recruited 502,633 people for their study to determine associations between osteoarthritis, rheumatoid arthritis and frailty. Of the total number of participants, 4894 had rheumatoid arthritis (1.1%), 35,884 had osteoarthritis (7.8%) and 513 reported both (0.1%).
In comparison to the whole cohort, patients with osteoarthritis and rheumatoid arthritis tended to be older (mean age, 59-60 years old), female participants with a greater BMI.
All participant data was collected via the UK Biobank, a population-based prospective cohort of men and women from the United Kingdom. Invitations to participate in the study were sent to individuals 40-69 years of age who lived nearby the 22 assessment centers throughout England, Wales and Scotland.
Participants visited the assessment centers between 2006-2010 and provided data on demographics, lifestyles, smoking status (never, past, or current), physical (International Physical Activity Questionnaire) and medical history, and comorbidities via a questionnaire.
Follow-up assessments occurred between 2009-2013 and 2014-2016.
In addition to the questionnaire, investigators measured the frailty of participants using a frailty index (FI) and modified frailty phenotype. Both had been previously used in the UK Biobank.
The adapted frailty phenotype was comprised of 5 components: low grip strength, slow walking speed, weight loss, low physical activity, and exhaustion. The presence of 3 or more of the deficits indicated a frail participant.
Negative binomial random effects models were used to account for correlations in repeated measurements of FI at follow-up assessments for participants with osteoarthritis and rheumatoid arthritis.
The investigators reported the overall FI of the cohort, as well as participants with rheumatoid arthritis and osteoarthritis. “The mean (SD) frailty index at baseline among the whole cohort was 0.13 (0.08), among participants with RA was 0.18 (0.08), and among participants with OA was 0.17 (0.09),” they wrote.
Additionally, the prevalence of frailty based on the Fried phenotype in the whole cohort was 3.4%, and was higher among those with rheumatoid arthritis and osteoarthritis, respectively, 18.6% and 10.0%.
Cook and colleagues would report that the mean FI increased with age in the whole cohort and was specifically higher among women in each age group.
The adjusted relative risk ratio (95% CI) for pre-frailty and frailty, respectively at baseline was higher among people with osteoarthritis and rheumatoid arthritis than those without. Similar results were recorded at baseline for both groups.
Finally, the comorbidities included in the study showed an increased risk of pre-frailty and frailty at baseline for participants with osteoarthritis and rheumatoid arthritis.
Significant additive interaction between the presence of rheumatoid arthritis and osteoarthritis and all the individual comorbidities considered and the risk of frailty at baseline was recorded.
The AP between rheumatoid arthritis and stroke/TIA and the risk of frailty was highest (0.60; 95% CI, 0.38-0.82), followed by rheumatoid arthritis and depression (0.53; 95% CI, 0.35-0.70), and RA and CHD, (0.52; 95% CI, 0.36-0.68).
Considering interaction with OA, the AP between osteoarthritis and diabetes and the risk of frailty was highest, (0.49; 95% CI, 0.42-0.55), followed by OA and CHD, (0.48; 95% CI, 0.41-0.55), and OA and depression (0.47; 95% CI, 0.41-0.53).
The results recorded in the most recent study by Cook and colleagues mirrored results found in previous studies regarding osteoarthritis, rheumatoid arthritis and incidences of frailty. However, new information such as higher rates of change in FI in osteoarthitis participants remained unclear.
Additionally, ascertainment of both conditions was self-reported, which the investigators believed could have led to misclassifications that negatively impacted their findings.
Despite this, Cook and colleagues were able to show that people with osteoarthritis and rheumatoid arthritis are more likely to have and develop frailty, especially with the common comorbidities both groups share.
“Our data indicate that those with arthritis and these comorbidities are at higher risk of frailty and underscores the importance of targeted interventions to prevent and manage such co-morbidities in these patients,” the team wrote.
The study, “Increased frailty in people with osteoarthritis and rheumatoid arthritis and the influence of co- morbidity: an analysis of the UK Biobank cohort,” was published online in Arthritis Care & Research.