"You can estimate hemodynamics with echocardiography but not accurately enough," she added.

Many clinical trials in PAH used the NIH equation to suggest improvement in survival by comparing observed survival rates on a study drug versus survival rates predicted by the NIH equation, the study says. Since the NIH equation understates contemporary survival, it has led to more favorable comparisons of clinical trials testing new drugs to treat PAH, according to Gomberg.

"Our research suggests a reason that the drugs currently approved to treat PAH do not always work as well as we hope-because they were not held to a higher contemporary standard during their development and post-approval," Gomberg said. "The new equation should ameliorate this bias.

"Although some of these drugs dramatically improve the condition of some patients, none of them improves hemodynamics to normal levels," she added. "Therefore, we, as a medical community, have to acknowledge the fact that we have not yet cured PAH."

"This research would not have been possible without the collaboration of the entire PAH team at the University of Chicago and the tireless efforts of two young physician scientists, Thenappan Thenappan, MD, Cardiology fellow at The University of Chicago, and Sanjiv Shah, MD, a former Cardiology fellow at The University of Chicago and current faculty member at Northwestern," Archer said.

Both are co-authors of the study, along with Gomberg, Archer, Stuart Rich, MD (Cardiology at The University of Chicago), and Lu Tian, ScD, (Preventive Medicine at Northwestern University).

The research team hopes that this report will motivate development of novel agents and epidemiologic research.

Source: University of Chicago Medical Center