Data support monitoring for multimorbidity in RA
medwireNews: The presence of multiple comorbidities accounts for a substantial proportion of the excess mortality risk observed among people with rheumatoid arthritis (RA), US researchers report.
Jeffrey Sparks (Brigham and Women’s Hospital, Boston, Massachusetts) and co-investigators say that their findings underscore “the importance of monitoring for the total disease burden” in patients with RA.
The study included 1007 women with RA and 10,070 non‐RA controls, matched for age and year of diagnosis, who were all participants of the Nurses’ Health Study (1976–2018).
During a median 20 years of observation, the overall mortality rate was 43% among the people with RA and 31% among those without RA. Cardiovascular mortality rates were 20% and 19%, respectively, while respiratory mortality rates were 12% and 7%, respectively.
After adjustment for potential baseline confounders in a Cox regression model, Sparks and team found that the people with RA had significantly increased risks for total, cardiovascular, and respiratory mortality, compared with controls, at hazard ratios (HRs) of 1.46, 1.54, and 2.75, respectively.
Further adjustment for post‐baseline lifestyle factors such as physical activity, BMI, diet, and smoking only slightly attenuated the risks, with corresponding HRs of 1.38, 1.39, and 2.40.
However, when the researchers also took multimorbidity into account they observed much stronger attenuation.
The Multimorbidity Weighted Index (MWI) they used included 61 chronic conditions, and the mean baseline score was higher among the RA cases than controls, at 4.2 versus 3.1. The musculoskeletal system was the greatest contributor to the MWI in both groups, and the RA patients accumulated these, as well as cardiovascular and pulmonary, comorbidities at a faster rate than the controls.
Adding the MWI to the Cox regression model resulted in attenuation of the HRs for total and respiratory mortality risk to 1.18 and 1.93, respectively, while the risk for cardiovascular mortality was no longer significant.
Writing in Arthritis Care & Research, Sparks and team suggest: “The residual elevation in the respiratory mortality even after accounting for MWI may indicate the importance of other factors that were not captured in the [Nurses’ Health Study].”
“These missing factors could include interstitial lung disease, infections, and disease-modifying antirheumatic drugs use.”
And the authors conclude that their findings “emphasize the need for rheumatologists and primary care providers to actively take part in monitoring for multimorbidity that RA patients are prone to developing.”
They add: “Although their roles may be less prominent than multimorbidity in the current study, lifestyle factors should not be disregarded.”
By Laura Cowen
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