SSc survival worse in patients with both ILD and PH: Study

Researchers examine characteristics of patients with SSc, ILD and PH

Andrea Lobo, PhD avatar

by Andrea Lobo, PhD |

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People with systemic sclerosis (SSc) have poorer survival when they also have both interstitial lung disease (ILD) and pulmonary hypertension (PH), a study in Germany has found.

Being a woman, having a higher body mass index — a measure of body fat — and better lung function were associated significantly with a lower mortality risk.

However, researchers noted that “survival of SSc patients in general and with pulmonary involvement has improved significantly over the last decades, which may be due to improved therapeutic options, use of combination therapies, improved interaction between different disciplines, and increased attention to this rare disease through national and international networking.”

The study, “Impact of systemic sclerosis-associated interstitial lung disease with and without pulmonary hypertension on survival – a large cohort study of the German network for systemic sclerosis,” was published in the journal CHEST.

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SSc is an autoimmune disease characterized by the accumulation of scar tissue in the skin and potentially internal organs, including the lungs, heart, kidneys, and gastrointestinal tract.

Lung involvement is the leading cause of death among people with SSc and may occur as ILD — scarring of the lungs that makes it difficult to breathe — and as PH, or high blood pressure in the blood vessels that supply the lungs. Patients also may have a combination of both ILD and PH.

The combined effect of ILD and PH in SSc prognosis has been researched before, but only in small studies. “There is therefore a need to better understand the characteristics of patients with SSc, ILD and PH and how these may link to disease mortality,” the researchers wrote.

To determine that, researchers analyzed the data of 3,257 people with SSc, for a mean of 3.45 years, from 2003 until March 2022. The patients were registered in the German Network for Systemic Sclerosis, an interdisciplinary collaboration of 25 clinical centers.

Most patients in SSc study were women

The majority of patients were women (80.2%). SSc diagnosis was at a mean age of 47.9 years and mean SSc duration from diagnosis  was 12.4 years. The participants’ mean age when pulmonary involvement was first recorded was 54.7 years.

As for the type of SSc, limited cutaneous SSc was the most frequent (54.2%), followed by diffuse cutaneous SSc (31.4%).

At the first visit, ILD was detected in around one-third of the participants (34.5%), which included patients with ILD only (28.3%) and those with both ILD and PH (6.1%). Pulmonary arterial hypertension (PAH) had a lower prevalence (4.5%).

Patients with diffuse SSc accounted for more than half of those with ILD, while those with PAH or no lung involvement usually had a limited form of the disease.

When lung involvement was first reported, patients with PAH and ILD-PH were significantly older than those with ILD only (53 and 52 years versus 47 years). The proportion of men was significantly higher among patients with ILD, either alone (23.6%) or together with PH (26.5%).

Those with ILD-PH had the lowest lung function, followed by patients with ILD, participants with PAH, and patients without pulmonary involvement. This was assessed with forced vital capacity (FVC) — the maximum amount of air one can forcibly exhale after a deep breath — and diffusing capacity for carbon monoxide (DLCO), which is a measure of the lungs’ capacity to transfer oxygen from the air sacs into the blood.

Moreover, most patients with ILD were treated with glucocorticoids (58.1% of those with ILD-PH and 54% of those with ILD) or immunosuppressants (67.7% with ILD-PH and 70.9% with ILD). Lower proportions of patients with PAH or without lung involvement were treated with these medications.

During follow-up, there was an increase in the prevalence of lung involvement, up to 47.6% of the ILD patients, 15.2% with both ILD and PH, and 6.5% with PAH. Accordingly, there was a decrease in the proportion of patients without lung involvement, from 61% at study start to 45.9%.

SSc with pulmonary hypertension and ILD most detrimental

Survival at five years was 96.4% in the group without pulmonary involvement. It was lowest in participants with both ILD and PH (79.1%), followed by those with PAH (85%) and ILD only (92.8%).

The risk of death was more than five times as high for people with ILD-PH, compared to those without lung involvement. In contrast, women, participants with a higher BMI, or with higher DLCO values, had a lower mortality risk.

Overall, the study demonstrated that “ILD is the most prevalent pulmonary involvement in SSc, while the combination of ILD and PH is associated with the most detrimental survival,” the researchers concluded.