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A third of the patients referred to a tertiary center with a diagnosis of pulmonary hypertension had been misdiagnosed, a cross-sectional study showed.

And among the 30% of patients who had been put on a drug before being referred to the specialized center, 57% of prescriptions were inappropriate, Mardi Gomberg-Maitland, MD, of the University of Chicago, and colleagues reported online in JAMA Internal Medicine.

"In spite of major efforts to educate medical professionals about pulmonary hypertension, our study demonstrates that patients diagnosed as having pulmonary hypertension often receive misdiagnoses and are prescribed pulmonary arterial hypertension [PAH]-specific medications contrary to guidelines," they wrote.

Gomberg-Maitland told 麻豆传媒 that the reasons for misdiagnosis and inappropriate prescribing likely have something to do with the low number of pulmonary hypertension specialists in the field.

"Pulmonary hypertension is so specialized within cardiology and pulmonary, and only a small fraction of practice," she said in an email. "I also think that with oral therapies, people forget that it is a fatal disease and think that they can treat with an oral without consequence."

Of the five WHO classifications of pulmonary hypertension, only one pertains to pulmonary arterial hypertension (PAH). Certain therapies -- prostacyclin analogs, endothelin receptor antagonists (ERAs), and phosphodiesterase-5 (PDE5) inhibitors -- are indicated specifically for PAH.

Treatments for the other four classifications are generally directed toward the underlying cause, the researchers explained.

Also, patients may have incomplete evaluations, which is why experts have pushed for evaluation at specialized pulmonary hypertension tertiary centers.

To assess the accuracy of pulmonary hypertension diagnoses in patients referred to those specialized centers, the researchers conducted a cross-sectional study during a 10-month period in 2010 and 2011 at three large tertiary pulmonary hypertension centers: Baylor College of Medicine, the University of Michigan, and the University of Chicago.

They included 140 patients who had a mean age 56; the majority (68%) had been referred to the center by a cardiologist or pulmonologist.

Most patients (62%) had WHO functional class III or IV disease -- indicating that they were referred to the center late in the course of disease, when proper treatment might be ineffective, the researchers wrote.

Overall, evaluation at the centers revealed that 40% of patients had PAH, 30% were unknown, and 16% had pulmonary hypertension secondary to lung disease or hypoxia.

Of the 98 patients who received a definitive diagnosis before they were referred to the center, 33% had been misdiagnosed.

The researchers also expressed concern over the fact that a large percentage of patients (42%) hadn't had catheterization to assist in diagnosis before they were referred to the tertiary center.

Of the 38 patients who had a right-heart catheterization for the first time at the center, 37% received a different diagnosis after the procedure. For the 21 patients who had catheterization of both sides of the heart, 52% had a different diagnosis afterwards.

"It is concerning to pulmonary hypertension specialists that patients are too often referred late in the course of their illness and administered PAH-specific medications without appropriate testing for monitoring of response and frequently without an accepted indication," Gomberg-Maitland and colleagues wrote.

They added that delayed referral to specialized pulmonary hypertension centers is a continuing problem, and that physician education efforts may need to be reevaluated.

In an editor's note, Rita Redberg, MD, of the University of California San Francisco and editor of the journal, called attention to the fact that the researchers found that half of patients who started on medications didn't have the type of pulmonary hypertension that would be expected to respond to those drugs.

"As these drugs have definite harms (liver failure, shock, edema), and no known benefit outside of [PAH], we consider this a 'Less is More' article," Redberg wrote.

From the American Heart Association: