Natural history of systemic sclerosis-related interstitial lung disease: How to identify a progressive fibrosing phenotype

The natural history of interstitial lung disease in patients with systemic sclerosis is highly variable. Historical observational studies have demonstrated that the greatest decline in lung function in systemic sclerosis occurs early in the course of the disease; however, not all patients experience a decline in lung function even in the absence of treatment. Furthermore, among patients who do experience a decline in lung function, the rate of decline can be either rapid or slow. The most common clinical phenotypes of systemic sclerosis-related interstitial lung disease are, therefore, as follows: (1) rapid progressors, (2) gradual progressors, (3) stabilizers, and (4) improvers. This review summarizes the features of systemic sclerosis-related interstitial lung disease patients who are more likely to experience rapid progression of interstitial lung disease, as well as those who are more likely not to experience interstitial lung disease progression. Understanding the clinical, biological, and radiographic factors that consistently predict interstitial lung disease-related outcomes in systemic sclerosis is central to our ability to recognize those patients who are at heightened risk for interstitial lung disease progression. With new options available for treating patients with systemic sclerosis-related interstitial lung disease, it is more important than ever to accurately identify patients who may derive the most benefit from aggressive systemic sclerosis-related interstitial lung disease therapy. Early therapeutic intervention in patients with this progressive fibrosing phenotype may ultimately improve morbidity and mortality outcomes in patients with systemic sclerosis-related interstitial lung disease.