Patient Selection
Medical records of the patients in the SSc cohort of the Rheumatology Department of Kocaeli University School of Medicine were reviewed. Among 164 patients who fulfilled the 2013 American College of Rheumatology/European League Against Rheumatism (ACR/ EULAR) SSc classification criteria between 2007 and 2019 [10], 135 patients with a baseline HRCT evaluation were included in the study. Thirty-eight gender- and age-matched healthy subjects, scanned for different indications from various outpatient clinics were enrolled. Demographic, clinical, and laboratory data were retrieved from medical records, including organ involvements due to SSc, autoantibody status, forced vital capacity (FVC), and carbon monoxide diffusing capacity (DLCO). The patients were classified into limited cutaneous SSc (lcSSc, n=85) or diffuse cutaneous SSc (dcSSc, n=50) according to LeRoy’s criteria [11].
PF was defined based on a range of morphological HRCT findings, including any one of the following: evident ground glass; honey combing; interlobular septal thickening; or traction bronchiectasis. The restrictive pulmonary disease pattern was characterized by a pulmonary function test showing a normal FEV1/FVC value (≥70%) and at least one of the following: FVC of <70% of predicted normal or DLCO of <70% of predicted normal [12]. In case of doubt about the findings (pneumonia, etc.), pulmonary involvement was confirmed with supportive findings in follow-up HRCTs. Patients with a diagnosis of other respiratory disorders such as asthma or chronic obstructive pulmonary disease, malignancy and significant pulmonary hypertension defined by previous clinical or echocardiographic evidence of significant right heart failure, low cardiac index (≤2 L/min/m² with right heart catheterization) or requiring parenteral therapy with epoprostenol were excluded.
The study was approved by Kocaeli University School of Medicine Ethics Committee, Kocaeli, Turkey, study number GOKAEK-2020/7.24.2020/118.