THU0367 INCIDENCE AND PREVALENCE OF SYSTEMIC SCLEROSIS-ASSOCIATED INTERSTITIAL LUNG DISEASE IN FLANDERS: A 12-YEARS COLLABORATIVE MULTICENTER PROSPECTIVE COHORT STUDY.

Abstract

Background:Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is the main cause of death in SSc and accounts for up to 30-35% of SSc-mortality (1-2). All SSc cases, irrespective of the extent of the skin disease, should be evaluated for ILD (3). The epidemiology of SSc-ILD in Belgium is unknown. In literature, the prevalence of ILD in SSc varies between 19% and 52%. However, different criteria were used to diagnose ILD (4). In 2008, Goh et al. proposed a flow diagram to diagnose SSc-ILD based on chest high-resolution CT-scan (HRCT) and pulmonary function tests (PFTs). Their categorization into limited or extensive ILD has prognostic value (5).Objectives:To determine the prevalence and incidence rate of SSc-ILD in Flanders.Methods:Up to 12-year follow-up data of consecutive SSc patients were obtained by 2 Flemish expert centres (University Hospitals Ghent and Leuven). Patients fulfilling the LeRoy and/or ACR-EULAR classification criteria were included consecutively in the prospective cohort (6). Patients received HRCT at baseline and on indication thereafter, as well as yearly PFT. All HRCTs were centrally analyzed (Ghent) and patients were categorized according to the Goh criteria as without ILD, with limited ILD (limILD) or with extensive ILD (extILD) (5).Results:Between 2006 and 2018, 797 SSc patients (557 Ghent/240 Leuven; 22% limited SSc (LSSc)/59% limited cutaneous SSc (LcSSc)/19% diffuse cutaneous SSc (DcSSc)) had baseline HRCT and PFT. The baseline characteristics are depicted in the table. The mean age (SD) was 53 +/-15 years and the majority of patients was female (76%).272 SSc patients had ILD at baseline, implicating a baseline prevalence of 34% (272/797). The baseline prevalences were 35% and 55% for the LcSSc and DcSSc subgroups respectively. During a median follow-up of 39 months (IQR: 11-79 months), 44 patients were diagnosed with incidental SSc-ILD, resulting in an incidence rate of 21,0/1000 person-years (PY), 95% CI:15,2-28,1. The incidence rates were 21,7/1000 PY, 95%CI: 14,3-31,6 and 43.9/1000PY, 95%CI: 22.7-76.8 for the LcSSc and DcSSc subgroups respectively.Table.Baseline characteristicsSSc (n=797)LcSSc (n=470)DcSSc (n=149)age (years) °53+/-1554+/-1554+/-14♂/♀ *193(24%)/604(76%)109(23%)/361(77%)58(39%)/91(61%)Disease Duration (months) #for 718: 22 (5-72)for 443: 25 (5-80)for 145: 16 (7-52)LSSc/LcSSc/DcSSc *178(22%)/470(59%)/149(19%)follow-up (months) #39 (11-79)38.5 (9.75-81)44 (17.5-78)Anti-centromere antibodies§252/538 (47%)163/317 (51%)19/108 (18%)Anti-topoisomeraseI antibodies§119/519 (23%)66/297 (22%)45/112 (40%)ILD at baseline, *272 (34%)163 (35%)82 (55%)LimILD, *230 (29%)139 (30%)67 (45%)ExtILD, *42 (5%)24 (5%)15 (10%)New ILD during follow-up, §44/52527/30712/67°: mean +/- standard deviation, *: number of patients (percent), #: median (interquartile range), §= number of patients/total number of patients with available data (%)Conclusion:In an unselected cohort of SSc patients, a third of the patients has ILD at baseline which is in line with previous prevalence reports. Importantly, this is the first study reporting incidence rates of SSc-ILD.