Patients with osteoarthritis (OA) and rheumatoid arthritis (RA) are more likely to be frail compared with the general population, according to research findings published in Arthritis Care & Research.

Although there exist some cross-sectional data to support an association between OA/RA and frailty, there is currently a lack of prospective research findings to support these data.

A team of UK researchers examined the association between frailty and OA and RA in 457,561 patients between the ages of 40 and 69 years (mean age, 56.5 years) who were part of the prospective UK Biobank cohort. A total of 1.1% patients in the cohort had RA (mean age, 59.2 years), and 7.8% patients had OA (mean age, 60.7 years).


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The researchers assessed frailty in this population using a frailty index (FI) and a modified frailty phenotype characterizing patients who were “robust,” “pre-frail,” and “frail.” The frailty phenotype comprises 5 variables: low grip strength, slow walking speed, weight loss, low physical activity, and exhaustion.

Multiple regression models were used to assess the association between RA and OA and frailty at both baseline and follow-up. In addition, the researchers examined the impact of comorbidities (eg, cardiovascular disease, diabetes, chronic obstructive pulmonary disease, and depression) on the association between frailty and OA and RA.

At baseline, patients with OA were more likely to have the frailty phenotype than those without OA (relative risk [RR], 3.41; 95% CI, 3.26-3.56). Those with RA were also more likely to be frail at baseline compared with those without RA (RR, 10.66; 95% CI, 9.73-11.69).

A total of 202 patients with RA and 1811 patients with OA at baseline were included in the longitudinal analysis (median follow-up period, 5.1 years). The investigators found 554 incident cases of frailty during the follow-up, as assessed with the frailty phenotype. There were 89 cases of frailty in patients with OA vs 15 cases of frailty in patients with RA.

In the longitudinal analysis, the presence of RA was associated with an increased incidence rate ratio (IRR) for frailty (adjusted IRR, 2.82; 95% CI, 1.73-4.59). The presence of OA at baseline was also associated with an increased IRR for frailty in the longitudinal analysis (adjusted IRR, 1.66; 95% CI, 1.32-2.09).

The FI was 35.2% (95% CI, 24.1-47.2) higher at baseline in patients with vs without RA who had 1 or more follow-up assessment. Although there was no difference in the rate of change of FI over time in the RA vs non-RA group, the rate of increase of FI was greater in patients with vs without OA at baseline.

In patients with OA and RA, each individual comorbidity was associated with an increased RR of pre-frailty and frailty at baseline. The researchers noted that there was an additive interaction between RA, OA, and each comorbidity that increased the prevalent frailty.

The highest attributable percentage of risk from interaction (AP) was between RA and stroke/transient ischemic attack and the risk for frailty (AP, 0.60; 95% CI, 0.38-0.82), followed by RA and depression (AP, 0.53; 95% CI, 0.35-0.70) and RA and coronary heart disease (AP, 0.52; 95% CI, 0.36-0.68).

Limitations of this study included the predominantly older patient population, the high rate of women with RA (69.2%) and OA (64.6%), and the inclusion of UK Biobank individuals who were less likely to reside in socioeconomically deprived areas.

In spite of these limitations, the researchers suggest the findings underscore “the importance of targeted interventions to prevent and manage such co-morbidities in these patients” with RA and OA, particularly those with comorbidities.

Reference

Cook MJ, Verstappen SMM, Lunt M, O’Neill TW. Increased frailty in people with osteoarthritis and rheumatoid arthritis and the influence of co-morbidity: an analysis of the UK Biobank cohort. Arthritis Care Res (Hoboken). Published online July 7, 2021. doi:10.1002/acr.24747