Are 50% of asthma cases misdiagnosed?

More than half of children with asthma may be misdiagnosed, according to a new study.

The study, published in the British Journal of General Practice, was conducted by researchers in the Netherlands on children treated across four health centers.

Lead study author Ingrid Looijmans, MD, PhD, general practitioner and special interest practitioner for asthma and chronic obstructive pulmonary disease at University Medical Center Utrecht in Utrecht, Netherlands, stresses that the report reveals overdiagnosis, but not necessarily overtreatment, of asthma, and that pediatricians who have doubts about a symptom-based diagnosis should continue using that diagnosis until it can be confirmed using other testing methods.

Related: Rethinking asthma, prevention and management

“A good asthma diagnosis is difficult in primary care, probably partly because lung function tests are not widely available in primary care-at least not in the Netherlands,” Looijmans says. “So maybe it would be helpful if general practitioners and pediatricians would make agreements on how to better structure the diagnostic process for asthma in children and maybe make lung function testing in the hospital more accessible.”

Diagnosis of asthma is typically made through a combination of data from the patient’s medical history, physical examination, lung function tests, and more, although pulmonary function tests are not accurate in children aged under 6 years. However, it can be difficult for children to receive additional diagnostics later in childhood.

“Assessment of lung function is regarded as essential for the diagnosis and therefore advised in all asthma guidelines to ensure a correct diagnosis, because signs and symptoms alone are insufficient,” the study notes. “A study in the United States found that 75% of family physicians perform spirometry on children. Surprisingly, only 36% of them indicate routine use to establish an asthma diagnosis as recommended by national guidelines.”

In the Netherlands, as well, barriers include the need for a referral to a hospital for the testing, creating a hurdle for general practitioners and possible leading to overdiagnosis, according to the study.

“Overdiagnosis gives rise to overprescription and incorrect use of medication, and to anxiety in parents and children,” the study authors note.

Although previous studies have indicated that asthma is probably overdiagnosed in children, this is the first to quantify the extent of the problem and investigate the diagnostic process utilized prior to the diagnosis or misdiagnosis.

For the purpose of the study, asthma was considered confirmed in children aged over 6 years if there was recurrent dyspnea or wheezing, plus reversible bronchial obstruction confirmed through spirometry and possible some other pulmonary assessments. Children with probable asthma were defined as those whose diagnosis was based on a medical history and physical examination during an exacerbation, but without additional lung tests. This category also included children who used chronic inhalation medication without exacerbations, or who need chronic inhalation corticosteroids or beta-2 sympathomimetic drugs at least 3 times a year. Children who experienced no exacerbations and use little or no inhalation medication were considered unlikely to have asthma.

NEXT: Applying the study to a US population

Children who fell into the “unlikely” or “no” asthma categories were considered overdiagnosed for the purposes of the study, and children aged under 6 years whose diagnoses couldn’t be confirmed through spirometry were given symptom diagnoses with the caveat that the diagnosis be reviewed at a later time, according to the report.

In total, only 105 of the 652 children with asthma that were studied had their diagnosis confirmed through spirometry, according to the study results. More than 23% still needed additional lung testing to confirm an asthma diagnosis, and 53.5% of children were overdiagnosed-a total of 5 children were found to have no asthma and 344 were unlikely to have asthma, according to the researchers. Researchers also found that diagnostic codes were never changed for some children who were diagnosed based on symptoms at an early age and were then found not to have asthma with later testing.

In most of the cases studied where children were diagnosed without the use of spirometry, dyspnea, cough, and wheezing were the most common symptoms, and children were frequently seen in conjunction with a respiratory infection or prolonged exhalation during auscultation. A few children were also diagnosed using peak flow measurements and allergy testing.

Next: Spirometry establishes asthma control in children

“The fact that in this study lung function tests in the initial assessment were only used in a few children is consistent with previous reports of widespread underuse of spirometry in pediatric asthma,” the researchers note. “To avoid overtreatment, medicalization, and anxiety in parents, a more structured diagnostic strategy including lung function testing in children under suspicion of having asthma is warranted.

Despite the fact that the study was carried out in the Netherlands-a country that boasts one of the best healthcare systems in the world it could have important implications for practice in the United States. A misdiagnosis in a country ranked 17^th by the World Health Organization (WHO) for healthcare quality could spell trouble for the United States, currently rated 37^th in healthcare quality by WHO.

The number of asthma diagnoses in the United States. continues to grow, with an estimated 8% of the population having asthma in 2009-up 1% from 2001. According to the American Academy of Allergy, Asthma and Immunology (AAAAI), 185 children and more than 3000 adults died as a result of asthma in 2007, and it affects about 10% of children in the United States overall.

Asthma cost about $3300 annually per person as of 2007, according to AAAAI, with costs growing by $3 billion-or about 6%-over the prior 5-year period. Children with asthma miss an average of 4 days of school each year; 16% of deaths from influenza from 2001 to 2012 were in patients with asthma, says AAAAI.

Other nations are already working to recognize and reverse trends in overdiagnosis, including the United Kingdom, which has been developing new guidance for asthma diagnosis for more than 4 years. A healthcare services watchdog in the United Kingdom drafted new guidance for physicians in regard to asthma care based on data from research that suggests overdiagnosis is occurring and up to 30% of adults have no clinical symptoms of asthma. The proposed new guidelines are currently under review, but could be implemented by summer.