Interstitial Lung Disease Increases Mortality Risk in RA

Interstitial lung disease (ILD) was linked to higher mortality rates in patients with rheumatoid arthritis (RA). Risk factors in patients with RA-ILD included age, prednisone dose, chronic obstructive pulmonary disease (COPD), dementia, and diabetes mellitus (DM) with end-organ damage, according to a study published in Rheumatic & Musculoskeletal Diseases.¹

Given these results, investigators believe that “more judicious use of steroids among elderly patients with RA-ILD” may be beneficial, in addition to “screening for comorbidities of COPD and DM with end-organ damage as part of the routine in treating RA-ILD population.”

The 1997-2013 Taiwanese National Health Insurance Research Database (NHIRD) was used to identify 30,882 patients with RA-non ILD and 214 patients with RA-ILD via International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. RA-ILD was defined as 1 or more outpatient or inpatient visit using ILD-related ICD-9-CM codes, and a radiological or pathological diagnosis using the appropriate National Health Insurance (NHI) code within 6 months of the date of diagnosis. Patients with RA-ILD were matched 1:10 for sex, age, time of ILD diagnosis, and disease duration with healthy controls. Propensity score matching (PSM) was performed for selected comorbidities, the association of mortality with ILD was estimated for the 2 matched populations, and factors associated with mortality among patients with RA-ILD were evaluated.

A total of 164 patients with RA-ILD were selected before the PSM and 155 patients with RA-ILD were included after the PSM and compared with 1640 and 155 controls, respectively. The mean disease duration from RA diagnosis to ILD detection was 3.5±2.8 years.ILD was linked to mortality before PSM (aHR, 1.73; 95% CI 1.19 to 2.52) and in the PSM population (HR 4.38; 95% CI 2.03 to 9.43).

Of the patients with RA-ILD, significant risk factors included age (aHR 1.04; 95% CI 1.03 to 1.08), dementia, DM with end-organ damage, chronic obstructive pulmonary disease (COPD) (aHR 2.12; 95% CI 1.25 to 3.58), and corticosteroid dose (prednisolone equivalent, mg/day) (aHR 1.09; 95% CI 1.07 to 1.11).

The lack of smoking data, which may be an unmeasured confounder for RA-ILD mortality, limited the study. However, smoking-related comorbidities were evaluated. Additionally, diagnosis of RA and ILD may be questionable from the data provided, although patients were only included if a diagnosis was confirmed by 2 or more rheumatologists after a careful review of the individual’s medical records. There is also a possibility that asymptomatic RA-ILD was undetected. Lastly, results may not be generalizable to non-Taiwanese patient populations.

“This is one of the few population-based cohort studies to analyze the predictors of RA-ILD mortality,” investigators concluded. “Further studies are required to study the pathophysiology link between DM and RA-ILD as well as the effect of RA treatments on RA-ILD progression and mortality.”

Reference:

Ng KH, Chen DY, Lin CH, Chao WC, Chen HH. Analysis of risk factors of mortality in rheumatoid arthritis patients with interstitial lung disease: a nationwide, population-based cohort study in Taiwan. RMD Open. 2022;8(2):e002343. doi:10.1136/rmdopen-2022-002343