Background/Purpose: Interstitial lung disease (ILD) is a major contributor to morbidity and mortality in systemic sclerosis (SSc). We sought to identify the distribution of clinical characteristics, comorbidities, pulmonary disease patterns, and outcomes in a retrospective cohort of SSc-ILD.

Methods: A retrospective review of medical records was conducted to identify patients with SSc seen at a single tertiary referral center in 2000-2013 within 1 year of ILD diagnosis. All patients met the 2013 ACR/EULAR classification criteria for SSc. Patients were included only if at least 1 year of follow up data was available. Baseline demographics, comorbidities and clinical characteristics were collected, in addition to pulmonary function tests, lung imaging, and echocardiogram for 3 years after ILD diagnosis. Cox models were used to examine associations between potential risk factors and progression or mortality.

Results: A total of 126 patients with SSc-ILD were identified (87 [69%] female; mean age: 57.5, range 31-82 years). Based on high resolution chest CT (or biopsy when available), 108 (86%) were characterized as nonspecific interstitial pneumonia (NSIP), 17 (13%) as usual interstitial pneumonia (UIP), 1 as unclassifiable ILD. Pulmonary hypertension (PHTN) was noted in 44 (35%) at baseline, and this did not differ between ILD subtypes. Patients with UIP were more likely than those with NSIP to have chronic obstructive pulmonary disease (COPD) at baseline (24% vs 5%, p = 0.005). 89% had limited cutaneous SSc, 7% had diffuse cutaneous, and 4% SSc sine scleroderma. SSc specific serologies (i.e., SCL-70, centromere, and/or RNA Pol III) were positive in 56 (46%) patients, somewhat more common in NSIP than UIP (49% vs 25%; p=0.07). Baseline initial forced vital capacity (FVC) and diffusion capacity (DLco) were not significantly different between ILD subtypes. Progression to DLco < 40% predicted or too ill to perform DLco was noted in 39% (95% CI 30% – 48%) by 3 years and did not significantly differ between ILD patterns (p=0.64). Risk factors for progression included baseline DLco (p < 0.001), FVC (p = 0.001) and PHTN (p = 0.002). Only 5 patients progressed to FVC < 50% predicted. During a median of 5.0 years of follow-up, five-year survival was 86% (95% CI 80 – 92%), and was only marginally worse in UIP than NSIP (hazard ratio [HR]: 2.0; p=0.057). Risk factors for mortality included comorbid COPD, hypertension and those identified for progression. The presence of inflammatory arthritis at baseline (16 patients, 13%) appeared to be a good prognostic indicator for mortality (HR 0.21, 95% CI 0.05 – 0.89).

Conclusion: Outcomes were overall somewhat better in SSc-ILD compared with those described in idiopathic pulmonary fibrosis, consistent with previous studies of connective tissue disease related ILD. ILD subtype had marginal prognostic significance in this cohort of patients with SSc-ILD. Baseline FVC and DLco, comorbid COPD, hypertension, and pulmonary hypertension at any time were risk factors for a poor prognosis. These findings highlight the importance of a thorough baseline pulmonary evaluation in predicting outcomes in patients with SSc-ILD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/baseline-characteristics-and-outcomes-in-a-retrospective-cohort-of-patients-with-systemic-sclerosis-related-interstitial-lung-disease/