BIRMINGHAM, United Kingdom—Pulmonary arterial hypertension (PAH) is relatively uncommon in individuals with mild lupus, but patients with high levels of lupus anticoagulant are candidates for echocardiography, as are all lupus patients who are planning to become pregnant.

{}In an advance online article in Rheumatology1, Athiveeraramapandian Prabu, MD, Caroline Gordon, MD, and colleagues from the Queen Elizabeth Hospital in Birmingham, UK reported a significant association between lupus anticoagulant levels and PAH (defined as systolic pulmonary artery pressure greater than 30 mmHG at rest). In addition, they also found a borderline significant association between clinical antiphospholipid syndrome (APS) and PAH.

Senior investigator Caroline Gordon, MD, told MSK Report, “Clinicians should remember that PAH can occur in lupus patients (but is less common than in systemic sclerosis) and that those that have lupus anticoagulant and/or anti-phospholipid syndrome were most at risk in our study.” Dr. Gordon is in the Department of Rheumatology at the University of Birmingham Medical School.

Based on these two findings, the authors suggested that thrombosis “may play an important role” in PAH in patients with mild lupus.

Study Assessed PAH Risk Factors in Nearly 300 Lupus Patients

This cross-sectional study included 283 participants from lupus clinics in Birmingham, UK. The researchers checked a host of PAH risk factors, including the presence of lung disease, respiratory muscle weakness, autoantibodies, smoking, Raynaud's phenomenon (RP), and APS. The severity of patients’ lupus symptoms was assessed with the BILAG index (indicating disease activity in 8 organ systems) and the SLICC/ACR (indicating damage in 12 organ systems).

Prevalence of PAH in patients with mild lupus may be lower than suspected

Dr. Gordon said that this study provides some reassurance for clinicians treating lupus patients, in that PAH was relatively uncommon and was generally mild.

According to the authors, the point prevalence rate (4.2%) of PAH in this sample was “at the lower end of prevalence rates reported from previous studies.” However, this cross sectional study may be a more accurate snapshot of individuals with mild lupus, as other PAH prevalence estimates came from studies of individuals with severe forms of the disease.

In the current sample, only 29.3% of the patients had active lupus symptoms in one of the 8 organ systems measured by the BILAG index. In addition, 57.2% did not have any organ damage measured by the SLICC/ACR.

Patients with mild lupus likely to have mild PAH

Only 12 of the 283 participants had systolic pulmonary artery pressure greater than 30 mmHG. Systolic pulmonary artery pressure in patients with PAH ranged from 31-59 mmHG. “Most of the PAH cases were found to be of mild severity (<40 mmHG),” reported the researchers.

Translating research into practice: Use ECHO, not cath, for high-risk lupus

The study authors recommended moving away from heart catheterization, an invasive and expensive standard screening tool for PAH, in order to assess high-risk individuals. They note that transthoracic Doppler echocardiography (ECHO) has been shown to be a safe, sensitive, and specific tool for PAH screening.

Other non-invasive PAH assessments, such as pulmonary function tests, the six-minute walk test, and respiratory symptom questionnaires, may not be useful as screening tools in high-risk individuals with mild lupus, they write.

“PAH screening is not routinely needed but should be done for lupus patients considering pregnancy,” Dr. Gordon said.

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