Emerging Therapies for Interstitial Lung Disease - Episode 10
Alicia M. Hinze, MD: Systemic sclerosis is a complex autoimmune disease that has features of a vasculopathy as well as features of fibrosis, or progressive fibrosis, that can affect multiple organs. The diagnosis of systemic sclerosis can actually be relatively complex. Systemic sclerosis is a very heterogeneous disease. In making a diagnosis of systemic sclerosis, it really relies a lot on physical examination as well as clinical history.
Some of the clinical features I’ll see with systemic sclerosis can include Raynaud phenomenon, in which the fingers are extrasensitive to the cold, and they’ll actually turn white and blue and can also result in some ulcers on the digits. If not aggressively treated, it can be seen with evidence of interstitial lung disease that we’ve been talking about. It can be associated with pulmonary arterial hypertension in these patients. We can see skin changes marked by thickening of the skin. Sometimes that can just be eliminated to a little thickening over the fingers. But it can also be associated with really widespread skin thickening involving all the extremities and some of the face. It can be really profound in terms of the level of fibrosis that’s occurring. It is a chronic disease. Once a patient does have it, we unfortunately don’t have the cure, so we really focus on being able to treat the different manifestations of disease to improve overall morbidity and mortalities of the disease process itself.
The prevalence of systemic sclerosis can vary a little by region. In the United States we’ve seen prevalence range from 100 to 300 per million. In Europe or Japan, we’ve seen those numbers a little lower. I think the last number I saw was 88 per million. So it can vary a little bit by region.
The potential for development of interstitial lung disease in systemic sclerosis is relatively high. Again, it depends on the definition that we’re using. Simply having interstitial lung disease by imaging, we’ve seen ranges from 65% to 90% by imaging. For the subsets that are going to progress to have more severe lung disease, that subset is lower. Actual percentages can be a little difficult because it really depends on the characteristics of the cohort we’re looking at.
There are certain risk factors in scleroderma that are associated with progressive disease, like diffused skin thickening. There are certain autoantibodies that we test for in the blood that are associated with progressive lung disease. Race impacts risk, Caucasian versus African Americans. African Americans are at higher risk for progressive lung disease. Percentages can be a little difficult to pin down just because it can vary quite widely by the cohort. In 1 particular cohort of diffuse cutaneous disease—there are about 1000 patients in this particular cohort—about 16% of these patients developed pretty severe interstitial lung disease with this restrictive lung physiology on pulmonary function testing with an FVC [forced vital capacity] less than 55% that developed really severe lung disease or interstitial progressive interstitial lung disease in scleroderma.
Gary L. Johnson, MD, MBA: When you have lung disease that’s associated with systemic sclerosis, the healthcare resource utilization increases because of the pharmaceuticals and hospitalizations and the procedures. We don’t track that specifically because they are relatively small numbers of individuals, but certainly the healthcare resource utilization increases with the disease and with the comorbidities.