SAN DIEGO — About one-third of patients referred to an asthma specialty clinic who were believed to have difficult to control asthma actually had vocal cord dysfunction, results from a single-center study showed.
“If patients have been on many different medicines––they've been on oral or inhaled steroids and they're not responding––it's worth checking to see if they actually have asthma or not,” study coauthor Catherine Vitari, R.N., said in an interview during a poster session at an international conference of the American Thoracic Society.
In a study led by her associate, Dr. Sally E. Wenzel, a pulmonologist and the director of the Asthma Institute at the University of Pittsburgh Medical Center, the researchers reviewed the charts of 152 new patients evaluated at the institute between December 2006 and September 2008 in an effort to verify the diagnosis of severe asthma.
Of the 152 patients, 119 (78%) had a presenting diagnosis of asthma while 33 had another diagnosis such as dyspnea, cough, and emphysema.
Ms. Vitari, a clinical research nurse at the Asthma Institute, reported that 40 of the 119 patients who presented with an asthma diagnosis underwent methacholine challenges with laryngoscopy because their history and physical suggested asthma may not be the primary diagnosis. Of these 40 patients, 39 had a negative test, which precluded the diagnosis of asthma in 33% of the 119 patients. “We didn't expect to see this,” she commented. “That's a pretty high percentage of people referred for asthma who didn't actually have asthma.”
Dr. Wenzel performs a laryngoscopy at the time of the methacholine challenge “to see if the vocal cords are closing or spasming, indicating vocal cord dysfunction, or if it's truly asthma,” Ms. Vitari explained. “If you send the patient to ENT instead to do a laryngoscopy and they don't see anything, it could be that the vocal cord dysfunction isn't acting up at that time since the spasms can be episodic and/or related to triggering events, or stimuli.”
She acknowledged certain limitations of the study, including its single-center design and the fact that only one physician did the assessments. The researchers had no conflicts to disclose.