Background/Purpose: Rheumatoid arthritis (RA) is a common autoimmune disease affecting up to 1.0% of the US population. RA is most commonly associated with synovial inflammation and articular symptoms but is also associated with extra-articular manifestations. Interstitial lung disease (ILD) is one of the most important and common pulmonary manifestations of RA and it is associated with significant morbidity and mortality. We aim to find variations in the mortality trend of ILD in RA patients.

Methods: Death certificates from the CDC Wonder Database were analyzed from 1999 to 2020 for ILD (J84.1) and RA (M05 and M06) patients. Age-adjusted mortality rates (AAMR) per 100,000 individuals, average annual percentage change (AAPC), and annual percent change (APC) with respective 95% CI were calculated and stratified for gender, racial, age, and geographic factors.

Results: A total of 10171 ILD and RA-associated deaths occurred between 1999 and 2020 with an overall AAMR of 0.2. AAMR declined from 0.2 in 1999 to 0.1 in 2020 with an AAPC of -3.08 ( -4.79 to – 2.28; p< 0.01). From 1999 to 2014, a slight non-significant decrease was noted in mortality (APC -0.17), followed by a significant sharp decline from 2014 to 2017 (APC -24.09; p< 0.05)) and a gradual non-significant increase till 2020 (APC 6.70). Adults >55 years had higher AAMR than the population < 55 years of age, and AAMR continued to increase as age increased. Females accounted for 63.5% (n=6463) of deaths and had higher AAMR of 0.2 compared to men (0.1) but had a sharp decline noted in AAMR from 2017 to 2020 (APC -24.97 [-43.01 to -2.83]). In the racial and ethnic groups, non-Hispanic (NH) Black or African American and Asian or Pacific Islanders had the lowest AAMR of 0.1 whereas the highest was observed in American Indian or Alaska Natives (0.5). White population accounted for most deaths reported (80.7%) and a significant downtrend was noted in the mortality trend from 2014 to 2020 (APC -11.99; p< 0.01). There was no difference in AAMR between Rural (0.2) and Urban (0.2) settings, but later had a falling mortality trend from 2013 to 2016 (APC -23.64 [ -30.21 to -14.88], p< 0.01). The Northeast had the lowest AAMR of 0.1 whereas Midwest, South, and West had equally high AAMR of 0.2. Seven states (Idaho, Minnesota, Montana, New Mexico, Oregon, South Dakota, and Vermont) had the highest AAMR.

Conclusion: There has been a slight decrease in mortality rates from ILD in RA patients which could be due to advancements in treatment regimens. Females are more prone to developing autoimmune diseases, have higher AAMR, and therefore can contribute to a higher mortality burden. The older population was noted to have higher mortality rates. Noticeable differences were noted among different ethnic and racial groups as well as census regions and states in terms of mortality. Further research is warranted to identify the disparities noted.

Mortality Trends of Interstitial Lung Disease in Rheumatoid Arthritis Patients in the U.S. Population, 1999–2020.

(A) By U.S. state; (B) By race/ethnicity; (C) By gender; (D) By rural vs. urban setting.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/gender-racial-and-geographic-trends-in-mortality-from-interstitial-lung-diseases-among-patients-with-rheumatoid-arthritis-in-the-u-s-population-1999-2020/