Prevalence and Clinical Characteristics of Rheumatoid Arthritis-Associated Interstitial Lung Disease at Srinagarind Hospital: A Retrospective Cross-sectional Study

บทคัดย่อ

Background: Interstitial lung disease (ILD) is a severe extra-articular manifestation of rheumatoid arthritis (RA) associated with increased mortality. Data characterizing RA-associated ILD (RA-ILD) in Thailand remain limited. This study aimed to estimate the prevalence of clinically recognized, HRCT-confirmed RA-ILD and describe the clinical, serological, radiological, and functional characteristics of affected patients at Srinagarind Hospital.

Methods: We conducted a retrospective cross-sectional study of adult patients with RA who attended Srinagarind Hospital, Khon Kaen University, from 2020 to 2024. RA-ILD was confirmed by high-resolution computed tomography (HRCT). The prevalence of clinically recognized, HRCT-confirmed RA-ILD was calculated using all identified patients with RA as the denominator. Characteristics of patients with RA-ILD were summarized using descriptive statistics.

Results: Among 1,054 patients with RA, 21 had clinically recognized, HRCT-confirmed RA-ILD, corresponding to a prevalence of 2.0% (95% CI 1.3–3.0%). The mean age of patients with RA-ILD was 62.8 ± 10.9 years, 81.0% were female, and 4.8% had a smoking history. Mean RA duration was 13.5 ± 8.9 years, and 76.2% had low disease activity or remission when ILD was identified. All patients were rheumatoid factor positive and had radiographic bone erosion, whereas 47.6% were anti-CCP positive. The usual interstitial pneumonia (UIP) pattern was the most common HRCT finding (52.4%), followed by non-specific interstitial pneumonia (NSIP; 38.1%). FVC impairment was recorded in 81.0%.

Conclusion: Clinically recognized, HRCT-confirmed RA-ILD affected 2.0% of patients with RA at Srinagarind Hospital. Patients with RA-ILD commonly had long-standing RA, RF positivity, radiographic bone erosion, a UIP pattern, and impaired FVC. Because this descriptive study did not include a non-ILD comparison group, the observed characteristics should not be interpreted as independent risk factors.