Interstitial Lung Diseases in a Longitudinal National Cohort of Veterans with Connective Tissue Diseases

Introduction

Interstitial lung diseases (ILDs) are a common manifestation in certain connective tissue diseases (CTD). Our study aims to describe the prevalence and time to diagnosis of CTD-ILD in veterans.

Methods

We used the Veterans Affairs Corporate Data Warehouse to select veterans with a) age ≥18 years, b) ≥ two ICD9 or ICD10 codes for Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus, Systemic Sclerosis (SSc), Sjogren’s, Dermatomyositis/Polymyositis, Overlap, and Other CTD separated by ≥6 months from 1999 to 2022, c) rheumatology visit within 6 months. ILD was identified by ≥ one ICD9 or ICD10 code for ILD one year before CTD diagnosis or any time after. Kaplan-Meier curves and Cox regression analyses were performed.

Results

88,559 veterans with CTD were identified with 8.8 (+/− 5.9) years of follow up. The majority were White males with RA and an average age of 60.4 years. 8,498 patients (9.6%) were diagnosed with ILD. 29% of veterans with CTD developed ILD within 1 year. Average time to diagnosis of ILD was 5.38 (SD 5.61) years. 42% of veterans with SSc were diagnosed with ILD while only 8% of veterans with RA developed ILD. The hazard of diagnosis of ILD in veterans with RA was 0.14 times compared to SSc (95%CI 0.13-0.15) adjusted for age, race, gender, smoking status, and CTD type.

Conclusions

In veterans, RA-ILD was the most common subtype, but veterans with RA were less likely to develop ILD compared to SSc. These results can influence strategies for ILD screening in patients with CTD.

Significance and Innovations

• The prevalence of ILD in a national cohort of veterans with CTD was 9.6%.

• The prevalence of ILD in veterans with CTD was highest in SSc (42%) and lowest in RA at 8%.

• 29% of veterans with CTD developed ILD within +/− 1 year timeframe of CTD diagnosis.

• The average time to diagnosis of ILD after a diagnosis of CTD is approximately 6 years.