SAT0476 Incidence, prevalence, mortality and performance of the acr/eular 2013 classification criteria in physician diagnosed systemic sclerosis: results from a population based us cohort (1980–2016)
Authors: A.S. Sandhu, C.S. Crowson, P.R. Bauer, E.L. Matteson, A. Makol
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Systemic Sclerosis (SSc) is a complex and heterogenous chronic inflammatory disease characterised by widespread fibrosis of the skin and visceral organs, microvascular injury and evidence of immune system activation. Diagnosis can be challenging in the absence of specific laboratory markers or diagnostic criteria. <h3>Objectives</h3> To determine the incidence, prevalence and mortality of physician diagnosed SSc in a population based US cohort and evaluate the performance of the ACR/<sup>EULAR 2013</sup> Classification criteria in comparison to the 1980 ACR criteria in classifying patients with SSc. <h3>Methods</h3> Medical records of patients with a diagnosis or suspicion of SSc in Olmsted County, Minnesota from January 1, 1980 to December 31, 2016 were reviewed to identify incident cases of SSc (defined by physician diagnosis). Prevalent cases of SSc in Olmsted County on January 1, 2015 were also identified. Incidence and prevalence rates were age and sex adjusted to the 2010 US white population. Survival rates were compared with the expected rates in the population of Minnesota. Fulfilment of the 1980 and 2013 classification criteria was ascertained. <h3>Results</h3> A total of 79 incident cases of SSc from 1980 through 2016 and 49 prevalent cases on Jan 1, 2015 were identified. Of these, 71 (90%) were females, 68 (87%) were caucasians, age at diagnosis 55.8±15.9 years (mean ±SD). The overall age- and sex- adjusted annual incidence for 1980–2016 was 2.7 (95% C.I. 2.1–3.3) per 1 00 000 population. The age-adjusted incidence was 4.6 (95% CI: 3.5–5.7) per 1 00 000 for females and 0.6 (95% CI: 0.2–1.1) per 1 00 000 for males, with no change in incidence over time. The age- and sex-adjusted prevalence on January 1, 2015 was 47.4 (95% CI: 34.1–60.7) per 1 00 000 population. 64 of 79 (81%) patients fulfilled the 2013 classification criteria, while only 48% fulfilled the 1980 criteria. All but 1 patient that fulfilled the 1980 criteria, also fulfilled the 2013 criteria. All 79 patients had Raynaud's, 38 had cardiopulmonary involvement (pulmonary artery hypertension and/or interstitial lung disease), 33 had digital ulcers/pitting scars, 66 had telangiectasias and 69 had sclerodactyly. 66 patients had limited cutaneous SSc, 11 had diffuse cutaneous SSc and only 2 had Sine scleroderma. 39 patients had a positive autoantibody for SSc: anti-centromere in 29, anti Scl-70 in 8 and anti RNA-polymerase III in 2. Mortality among SSc patients was significantly higher in comparison to the general population (standardised mortality ratio, 2.24; 95% C.I., 1.52–3.18). Figure 1 demonstrates survival of 79 Olmsted County residents with incident SSc compared to expected rates from Minnesota lifetables (observed: solid line; expected dashed line). <h3>Conclusions</h3> The average incidence of SSc in this population-based US cohort was 2.7 per 1 00 000 population with no change in incidence over the 36 year period of study. The new 2013 classification criteria perform significantly better than the 1980 criteria, but failed to classify 19% of patients in this cohort. Overall survival of patients with SSc is worse than the general population with no evidence of improved survival over time, indicating an unmet need for early diagnosis and more aggressive management. <h3>Disclosure of Interest</h3> None declared