SSc prognosis worse when PAH, ILD are comorbidities

Australian study examines quality of life, survival outcomes in this high-risk group

Andrea Lobo, PhD avatar

by Andrea Lobo, PhD |

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People with systemic sclerosis (SSc) have poorer quality of life and survival when they also have pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD), a study in Australia found.

Having PAH was associated with a poorer prognosis than having extensive ILD.

“A better understanding of people with SSc with PAH and ILD is critical in optimising management and identifying opportunities for improved survival,” the researchers wrote.

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The study, “Clinical characteristics and survival of pulmonary arterial hypertension with or without interstitial lung disease in systemic sclerosis,” was published in the journal Arthritis Research & Therapy.

SSc, also known as scleroderma, is characterized by the accumulation of scar tissue (fibrosis) and damage to the skin and sometimes internal organs, such as the lungs, kidneys, heart, and digestive system.

PAH, or high blood pressure in the vessels that supply the lungs, and ILD, characterized by lung inflammation and fibrosis, are leading causes of death among people with SSc. Generally viewed as independent manifestations, some individuals develop both conditions simultaneously.

In this study, researchers compared the clinical characteristics, survival, and quality of life of people with SSc and concurrent PAH and ILD, with those with SSc and either PAH or ILD alone, or with SSc only (neither PAH nor ILD).

Multicenter study

They analyzed 1,561 SSc patients recruited from the Australian Scleroderma Cohort Study (ASCS), a multicenter study of SSc. The majority of the participants (86%) were women, 74% had limited SSc, whereas 26% had diffuse SSc.

Most patients had SSc only (62%), 24% also had ILD, 7% had SSc and PAH, and another 7% had SSc with both PAH and ILD. People with PAH-ILD were more frequently men, with diffuse skin involvement, higher levels of inflammatory markers, older age at SSc onset, and extensive ILD. People of Asian origin more frequently developed SSc with PAH-ILD.

The participants were followed up between 3.3-4.1 years, a period that was slightly longer for those with ILD or both PAH and ILD.

People with PAH-ILD or PAH, but not ILD, had worse WHO functional class and lower 6-minute walk distance (a measure of exercise capacity) than those with SSc and ILD. Also, those with PAH-ILD had the poorest lung function.

In this study, PAH-specific monotherapy (only one medication) was more common than dual therapy (two medications) in SSc patients with PAH or with PAH-ILD. Triple therapy was more common in those with PAH relative to the group with both PAH and ILD. Endothelin receptor antagonists (which include Opusmit and Tracleer) were the most commonly prescribed treatments for PAH, followed by phosphodiesterase type 5 inhibitors (Adcirca and Revatio) and prostacyclin analogues (Flolan, Remodulin, Ventavis).

According to the Scleroderma Health Assessment Questionnaire and the 36-Item Short Form Health Survey, quality of life was worse in those with PAH-ILD, PAH or ILD than in patients with SSc only. Participants with PAH-ILD had a 12-fold increased risk of worse physical health than the overall SSc population relative to the SSc-only group.

“There was no difference in [mental health scores], perhaps indicating that the psychological burden of SSc is significant regardless of associated complications,” the researchers wrote.

Survival was reduced significantly in those with PAH and PAH-ILD. Among participants with PAH-ILD, survival was poorer with increasing ILD severity.

Model of all-cause mortality

In a model of all-cause mortality, extensive ILD combined with PAH demonstrated the worst systemic sclerosis prognosis, with a risk of death more than 5 times higher following disease onset, followed by the SSc group with PAH, extensive ILD only, and both PAH with limited ILD.

Protective factors included having anti-centromere antibodies, which are a type of self-reactive antibody found in SSc patients (35% lower risk of death), and being female (39% lower).

“The presence of PAH confers a poorer overall prognosis than even extensive ILD; however, further data are required to better understand the clinical outcomes of this high-risk patient group,” the researchers wrote.