Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


The Degree of Skin Involvement Predicts Distinct Interstitial Lung Disease Outcomes in Systemic Sclerosis.

Cottrell,  Tricia R., Wigley,  Fredrick, Wise,  Robert, Boin,  Francesco

Purpose:

Systemic sclerosis (SSc) is conventionally classified into limited and diffuse based on the extent of skin fibrosis. While this classification has some clinical utility and facilitates compatibility among patient groups for research purposes, the cutaneous involvement in SSc is heterogeneous and more specific skin subsets may be associated with unique clinical outcomes. In this study, we analyzed longitudinal data from a large cohort of well-characterized SSc patients to determine whether specific SSc skin subtypes can be associated with the development and severity of interstitial lung disease (ILD).

Methods:

A retrospective analysis was conducted on a longitudinal cohort of 2054 SSc patients seen at the Johns Hopkins University Scleroderma Center between 1976 and 2010. Based on the maximum extent of skin fibrosis, 4 SSc subsets of patients were identified: Type 0 if no cutaneous sclerosis (sine scleroderma) was present; Type 1 if sclerosis was distal to the metacarpophalangeal joints with or without involvement of the face; Type 2 if skin changes were distal to the elbows or knees; Type 3 if sclerosis extended proximally to the elbows or knees. The primary outcomes were the presence of interstitial lung disease (ILD) defined as a forced vital capacity (FVC) < 80% of predicted with no evidence of obstructive lung disease, and time from disease onset (1st non-Raynaud's symptom) to development of ILD. Chi squared test and analysis of variance were used to compare cumulative frequency and severity of ILD, while Kaplan-Meier method, log-rank test and Cox proportional hazard ratio were used to compare ILD-free survival curves from SSc onset and to estimate the probability of developing ILD in the different disease subsets.

Results:

The proportion of patients diagnosed with ILD significantly increased from type 0 to type 3 SSc subtypes (p<0.0001), while the average minimum FVC decreased (p<0.0001). Analysis of ILD free survival curves showed that over time, a greater extent of skin fibrosis was associated with a higher risk of developing ILD.

In particular, patients with type 2 SSc exhibited a distinct risk of ILD development (vs. Type 1 p = 0.0005; vs. Type 3 p=0.0001). This difference was supported also by the Cox proportional hazard ratio analysis demonstrating a significantly increased hazard of developing ILD for type 2 patients relative to type 1 (HR 1.5 [1.2–1.9], p<0.001), which was even higher for type 3 patients relative to type 1 (HR 2 [1.8–2.4], p<0.001).

Conclusions:

The degree of skin involvement is predictive of different outcomes in SSc-ILD. In particular, SSc patients with an intermediate level of skin fibrosis (type 2), who normally are classified into the limited SSc group, exhibit a distinct risk profile for lung involvement and therefore their identification and characterization may be relevant in term of prognosis and proper clinical management.

To cite this abstract, please use the following information:
Cottrell, Tricia R., Wigley, Fredrick, Wise, Robert, Boin, Francesco; The Degree of Skin Involvement Predicts Distinct Interstitial Lung Disease Outcomes in Systemic Sclerosis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :596
DOI: 10.1002/art.28364

Abstract Supplement

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