SAN DIEGO – Asthma may be overdiagnosed in many obese African American women who present with dyspnea, results from a small pilot study suggest.
The finding is important because the incidence rates of asthma and obesity have increased over the last 20 years, especially among African American women, Dr. Daniel Waggoner reported during a poster session at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
“If somebody gives you a very good history of asthma symptoms, sometimes it's a little bit easier to make the diagnosis,” Dr. Waggoner, of the division of allergy and immunology at Creighton University, Omaha, Neb., said in an interview.
“But if somebody comes in with rather nebulous symptoms, it's very important to get some objective testing to make a diagnosis [of asthma], because many medications [for it] have side effects, and they're expensive,” Dr. Waggoner continued.
He and his associates evaluated 18 African American women aged 19-50 years who live in or near Omaha and who had a physician diagnosis of asthma for at least 3 months. All had a body mass index (kg/m
Over the course of three office visits, the researchers performed the following measurements in each patient to verify the asthma diagnosis: spirometry with postbronchodilator values, exhaled nitric oxide (eNO), methacholine challenges, and full-body plethysmography. Each of the four tests was considered a positive criterion for the diagnosis of asthma.
Dr. Waggoner reported that of the 18 patients, only 8 (44%) had a positive methacholine challenge, 1 (6%) had demonstrated airway reversibility on spirometry, 10 (56%) had elevated eNO, and 6 (33%) had airflow obstruction as measured by plethysmography.
No patient met all four criteria for the diagnosis of asthma, and only 39% met two or more of the criteria.
“Only one patient did not have an albuterol prescription,” Dr. Waggoner added during the interview. “I was really surprised that we didn't have at least a handful more [who] demonstrated reversibility with albuterol or a bronchodilator.”
In their poster, the researchers concluded that in African American women who present with dyspnea, “an eNO and methacholine challenge should be considered to confirm or refute the diagnosis of asthma. Full-body plethysmography may provide clues to etiologies of dyspnea other than asthma, [such as physiologic air trapping] associated with obesity.”
The study was funded by the State of Nebraska Tobacco Settlement.
'If somebody comes in with rather nebulous symptoms, it's very important to get some objective testing.' DR. WAGGONER