Scleroderma is an autoimmune condition where the body’s immune system attacks its own tissues. When this process affects the lungs, it can cause interstitial lung disease (SSc-ILD), a condition characterized by scarring, or fibrosis. This scarring stiffens the lungs and makes breathing difficult. The presence of ILD is a complication of scleroderma that influences a person’s long-term health outlook.
Understanding Scleroderma-Associated ILD
Scleroderma, or systemic sclerosis, is a chronic autoimmune disease that triggers the overproduction of collagen, a component of connective tissue. This leads to the hardening of the skin and can impact internal organs. When the immune system targets the lungs, it causes inflammation in the interstitium, the tissue surrounding the air sacs. Over time, this inflammation is replaced by fibrosis, which impairs the lungs’ ability to transfer oxygen into the bloodstream.
The likelihood of ILD correlates with the type of scleroderma. The two primary forms are limited cutaneous and diffuse cutaneous scleroderma. ILD is more common and progresses more rapidly in the diffuse cutaneous type. The presence of anti-topoisomerase I (anti-Scl-70) antibodies in the blood also signals a higher probability of developing ILD.
Factors That Influence Prognosis
The course of SSc-ILD varies, and several factors help determine a prognosis. Pulmonary function tests (PFTs) are non-invasive breathing tests that measure lung function. Two measurements are the Forced Vital Capacity (FVC) and the Diffusing Capacity for Carbon Monoxide (DLCO). FVC measures the total amount of air you can forcefully exhale, indicating lung capacity, while DLCO assesses how efficiently oxygen moves into the bloodstream. A decline in these numbers, especially a drop in FVC of 10% or more within a year, indicates disease progression.
A high-resolution computed tomography (HRCT) scan is the most effective method for visualizing the extent of fibrosis. These scans produce cross-sectional images that show how much lung tissue is affected by scarring. Patients with more than 20-30% of their lungs showing fibrosis on a baseline HRCT have a worse prognosis. A staging system categorizes patients into “limited” or “extensive” disease based on these scans to help guide treatment.
Other clinical factors also influence the outlook. A person’s age at diagnosis can affect their prognosis, with older age being associated with worse outcomes. The presence of other health conditions, or comorbidities, also impacts survival. A serious complication is pulmonary arterial hypertension (PAH), a type of high blood pressure in the lungs. The coexistence of ILD and PAH is linked to a poorer outcome than either condition alone.
Estimating Life Expectancy and Survival Rates
Life expectancy estimates are statistical averages, not individual certainties, and the prognosis for SSc-ILD is highly variable. The presence of ILD is the leading cause of mortality in people with scleroderma. Population studies provide survival rate estimates, often in terms of 5-year and 10-year survival. For instance, one Canadian study found the 5-year survival rate for SSc-ILD to be 44.4% and the 10-year survival rate to be 22.0%.
A French study reported a 5-year survival rate of 70.5%, showing how outcomes can differ across populations and improve over time. These statistics depend on prognostic factors. Survival is significantly higher for individuals with limited disease on their HRCT scan compared to those with extensive disease.
Median survival, the time at which half of patients in a study are still alive, can range from 7 to 15 years after diagnosis. This is heavily influenced by disease severity. These figures are improving as medical management becomes more advanced. The data reflects historical outcomes, and the outlook for a person diagnosed today is likely better.
Medical Management and Its Impact on Outlook
Managing SSc-ILD aims to slow the progression of lung fibrosis, manage symptoms, and maintain quality of life. This relies on consistent monitoring and targeted therapies. Regular follow-ups every 3 to 6 months include repeating pulmonary function tests to track changes in lung capacity. This monitoring allows doctors to detect progression early and adjust treatment.
Medications are used to manage the disease process, often involving two classes of drugs: immunosuppressants and antifibrotics. Immunosuppressive agents, like mycophenolate mofetil, dampen the overactive immune response that drives inflammation. Antifibrotic drugs, such as nintedanib, directly target pathways involved in forming scar tissue to slow the rate of FVC decline. These medications may be used in combination.
Supportive care is another component of the treatment plan. For individuals with low blood oxygen, supplemental oxygen is prescribed to reduce breathlessness. Pulmonary rehabilitation, a program of exercise and education, can improve breathing efficiency and physical fitness. For a small number of patients with advanced disease, lung transplantation may be a treatment option.