WHO Group 1 PH (PAH, pulmonary arterial hypertension) can appear by itself of be associated with other medical conditions including connective tissue diseases (CTD), such as systemic lupus erythematosus (SLE). Although CTD-associated PAH is very common in people who have PAH, PAH is extremely uncommon among the many people with SLE. Because of this, a group of French researchers, supported by a grant from Actelion Pharmaceuticals France, looked to learn more about the traits of people with SLE-PAH and their survival rates.
Éric Hachulla, M.D., Ph.D., led an investigative team from hospitals, academic institutions and research facilities in exploring the subject of SLE-PAH, drawing data from the French Pulmonary Hypertension Registry. The study compared 51 patients who received their diagnosis of SLE-PAH by right heart catheterization (RHC) with 101 people who had SLE, but not signs of PAH. Each group shared similar ages and genders, and both carried a diagnosis of SLE for approximately the same amount of time. Additionally, the authors reported that about three-quarters of the people with PAH in the study were categorized in the New York Heart Association (NYHA) functional class III or IV when they received their diagnosis.
When the authors looked at what might predict mortality, they found that patients with lupus nephritis (inflammation of the kidney caused by SLE) and high pulmonary vascular resistance (PVR) had worse survival. They also noticed that when patients had more anti-SSA/SSB (antibodies associated with autoimmune diseases like SLE), they appeared to be more at risk for developing PAH.
On the other hand, Dr. Hachulla found that a different antibody, anti-U1-RNP (ribonucleoprotein), seemed to be associated with better outcomes, including survival. But they pointed to another study that offered different findings. This other study determined that the presence of anti-U1-RNP was linked to an increased risk of developing PAH in Chinese patients, suggesting that a patient’s ethnic background might be a factor in the development and progression of SLE-PAH. Dr. Hachulla’s team emphasized that more studies need to be conducted to confirm this finding.
The authors found that certain medication could have a positive impact on outcomes. Patients who received hydroxychloroquine when they were initially diagnosed, or within the following six months, had better survival rates. This particular drug has already been shown to improve survival rates in patients with SLE. They speculated that hydroxychloroquine, which is also used to treat malaria, might slow down autophagy, a cell degradation process, and prevent other proteins and enzymes from decaying. The authors noted that more work needs to be done to understand this association with hydroxychloroquine and better outcomes for people with SLE-PAH.
It is important to note that the sample size in this study was relatively small. Since this study examined data that was collected in the past, some of the data—for example data on antibody testing—may be missing and impact the overall results.
Dr. Hachulla and his colleagues reported that patients with SLE-PAH had a three-year survival rate of 89.4 percent and a five-year survival rate of 83.9. They reiterated their theory that anti SSA/SSB antibodies could be a risk factor, while anti U1-RNP antibodies could offer some protection and positively affect survival rates, but that more work needed to be done before fully understanding these theories.