In the rheumatology clinic evaluation of interstitial lung disease patients: A single center experience

The aim of our study is to determine the parameters that can be used in practical and early diagnosis by comparing the demographic, laboratory and clinical characteristics of patients diagnosed with interstitial lung disease (ILD) in autoimmune-related and non-autoimmune-related groups. In our study, patients who were evaluated by a pulmonologist at Afyonkarahisar Afyon Health Sciences University Faculty of Medicine Hospital between September 1, 2019, and September 30, 2023, and were referred to the Rheumatology Clinic for rheumatologic etiologies or were followed up with a diagnosis of SARD-ILD in the Rheumatology Clinic were included. By reviewing patient files and the hospital automation system, 247 patients over the age of 18 who were diagnosed with interstitial lung disease and had completed radiological and laboratory examinations were retrospectively analyzed in our hospital. Their demographic and clinical characteristics, laboratory and imaging findings, diagnoses, treatments, and comorbidities were examined. Patients were divided into two groups based on the etiology of ILD: SARD-ILD and non-SARD-ILD. Of the patients included in the study, 35.2% (n=87) were classified as having SARD-ILD, while 64.8% (n=160) were classified as non-SARD-ILD. Among the SARD-ILD group, systemic sclerosis was the most common associated disease, observed in 40.3% (n=35) of cases. In the SARD-ILD group, 67.8% (n=59) were female, and the mean age was 59.25±12.6 years. Imaging findings revealed a nonspecific interstitial pneumonia (NSIP) pattern in 47.1% (n=41) of cases. The most common clinical manifestation was arthritis/arthralgia, observed in 85.1% (n=74) of patients, while the most frequent serological finding was antinuclear antibody (ANA) positivity, detected in 70.1% (n=61) of cases. When comparing hemogram parameters, hemoglobin levels were significantly lower in the SARD-ILD group compared to the non-SARD-ILD group. Additionally, the systemic immune-inflammation index (SII) was significantly higher in the SARD-ILD group. According to the ROC analysis, an SII value of 637.72 was found to predict SARD-associated interstitial lung disease with a sensitivity of 65.5% and a specificity of 52.5%. Seven independent factors were identified as effective in distinguishing between the SARD-ILD and non-SARD-ILD groups. These factors included comorbidities, skin findings (such as skin dryness, digital ulcers, puffy edema, sclerodactyly, skin stiffness, calcinosis cutis, and rheumatoid nodules commonly seen in rheumatic diseases), joint involvement, ANA positivity, SII (Systemic Immune-Inflammatory Index), and PIV (Pan-Immune Inflammatory Value). It is suggested that these parameters should be considered in clinical practice for patients being evaluated for ILD and may serve as predictors for SARD-ILD. Keywords: Interstitial lung diseases, autoimmune-related interstitial lung disease, non-autoimmune interstitial lung disease, SII (Systemic inflammatory index), PIV (Pan immune value)