Huge numbers of patients with PAH miss out on combination therapy

By Mardi Chapman

23 Apr 2020

A significant proportion of patients with PAH remain undertreated on monotherapy, according to data from an Australian registry.

A study of more than 1,000 patients with Group 1 PAH enrolled in the Pulmonary Hypertension Society of Australia and New Zealand Registry found 51% were treated with monotherapy and 49% with combination therapy.

Importantly, only 66% of the patients on monotherapy were categorised as low risk using the REVEAL 2.0 risk assessment.

“Goal-oriented therapy is advocated to ensure that PAH patients receive optimal treatments as early as possible, since PAH can be a rapidly progressive disease with high mortality,” the study authors said.

“Guidelines recommend use of risk tools at diagnosis and each follow-up, targeting achievement of a low risk status.”

The study, published in Heart, Lung and Circulation, suggested many patients with PAH were not being appropriately escalated to combination therapy.

Endothelin receptor agonists were the most frequently prescribed class of drug (87%), followed by PDE-5 inhibitors (59% ) and prostacyclin analogues (12%).

Patients with idiopathic PAH (IPAH), heritable PAH (HPAH) and drug-induced PAH (DPAH) were more likely to be on combination therapy than patients with connective tissue disease-associated PAH (CTD-PAH) and congenital heart disease-associated PAH.

Lead author and respiratory physician Dr James Anderson told the limbic that the cost of combination therapy due to PBS restrictions was the obvious reason why so many patients remained on single agent therapy.

“The international guidelines do suggest there is a certain category of patients who might be suitable for monotherapy; in my mind that would be the person that is functionally very good – Functional Class 1 – or the elderly patients with a number of comorbidities.”

“Even accounting for those patients, there are still a huge number on a single agent that should be on dual agents.”

Dr Anderson, from the Sunshine Coast University Hospital, said education and awareness was part of the motivation behind the study.

“As part of that education, it’s a reminder of the latest guidelines and evidence being released which support the role of combination treatment.”

He acknowledged clinicians outside metropolitan centres often had to work hard at getting access to combination therapy for their patients.

“When I started work here we didn’t have any programs in place for the hospital to supply the cheaper PDE-5 inhibitors. I had to lobby pharmacy and submit applications for drug approvals to support the single agent which can be delivered by PBS.”

Compassionate access programs through pharmaceutical companies was another avenue, he said.

“Patients are very well educated as well. They are acutely aware of what is available and out there and will lobby for themselves.”

The study also noted the importance of non-pharmacological measures for PAH such as diuretics to offload fluids, correction of anaemia and iron stores, vaccination, supervised exercise training, supplemental oxygen, psychosocial support, and avoidance of general anaesthesia and pregnancy.

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