Even though asthma is more common in children than in adults, its definitive diagnosis in children remains elusive.1 The frequently used symptom-based approach to diagnosing asthma, often from parental reports, yields underdiagnosis and overdiagnosis of the disease, and often poor symptom control.1 In some cases, the rate of misdiagnosis has been as high as 53.5% in children.2

Although no single test can definitively diagnose asthma, several specialty societies, including the United Kingdom’s National Institute of Health and Care Excellence, recommend the objective tests of spirometry, bronchodilator reversibility, and fractional exhaled nitric oxide testing for children aged 5 years and older.1

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Spirometry, however, relies on the accuracy of the clinician performing and interpreting the test.1 Clinicians also acknowledge that it is nearly impossible to arrive at an acute diagnosis of asthma in children younger than 5 years because the testing largely relies on the patient’s cooperation.1 Moreover, many primary care offices do not routinely perform these tests, and in some cases, they may refer patients to hospitals for testing.1,2

Overdiagnosis of Asthma in Children

To determine the extent to which children are often overdiagnosed with asthma, Ingrid Looijmans-van den Akker, MD, PhD, from the University Medical Center Utrecht in The Netherlands, and colleagues conducted a study of 652 children (aged 6-17 years; mean age, 10.7 years; 40.6% girls) diagnosed with asthma. Pulmonologists then performed lung function tests, physical examinations, and histamine provocation tests to confirm the diagnosis.2

More than half the children had been overdiagnosed (53.5%), and only 16.1% had confirmed asthma.2 The clinicians in the study justified diagnosing asthma without further lung function tests if patients had dyspnea (31.9%), cough (26.0%), and wheezing (10.4%).2 Symptoms in 23.2% of the patients were consistent enough to suspect asthma.2 Of the children who did not have asthma, 64.2% were taking beta-2 sympathomimetics and 29.2% were receiving both beta-2 sympathomimetics and inhaled corticosteroids.2

“I hope clinicians now take more time to diagnose asthma in children correctly, and during this diagnostic process hold on to a symptom diagnosis (eg, dyspnea or wheeze),” said Dr Looijmans-van den Akker. “After a correct diagnostic process, they should continue with adequate follow-up.” As a result of their findings, Dr Looijmans-van den Akker and colleagues have developed a pediatric asthma care program in 8 primary care centers, and will analyze the results “to see if it indeed improves quality of asthma care in children.”

Keeping Tabs on Asthma Control

Once children have been diagnosed with asthma, they and their caregivers may find it difficult to control their disease.3 Adding to that challenge is that an estimated 60% to 80% of children who have asthma also have allergic rhinitis.3

To validate the Brazilian version of the Control of Allergic Rhinitis and Asthma Test for Children (CARATKids), a tool for determining whether children younger than 12 years have adequate control of their asthma and allergic rhinitis, João A. Fonseca, MD, PhD, from the University of Porto and the Center for Research in Health Technologies and Information Systems in Porto, Portugal, and colleagues examined 102 children, aged 6 to 12 years, at baseline and then at 4 to 6 weeks.3 The researchers used the childhood Asthma Control Test and total nasal symptom score to test the 2 major domains. A change of 3 points in the CARATKids tool was the minimal clinically important difference and validated the tool’s use as a solid patient reported outcome measure.

“Unfortunately, there is no robust, simple tool for asthma diagnosis, or even asthma screening, for children,” explained Dr Fonseca. “Rhinitis is underdiagnosed and undertreated in children, and often asthma is mistreated, both over- and undertreated, due to confounding effects of rhinitis. Since the questionnaire is filled in by the child and the parents, it promotes the active involvement of the family in the management of the disease, and can contribute to better clinician-family communication and shared decision making, crucial aspects to improve adherence, treatment, and outcomes.”

Variability Is Key to Diagnosis

One of the indications of an asthma diagnosis is the variability of lung function.4 Although some experts suggest that peak expiratory flow (PEF) tests performed at home can record the variability of lung function, in earlier studies, there was great overlap between patients with asthma and healthy patients.4

An alternative to the PEF test may be the forced oscillation technique, in which the patient’s lung function is recorded during quiet tidal breathing.4 Biomedical engineer Alessandro Gobbi, PhD, from the Polytechnic University of Milan in Italy, and colleagues studied 60 patients who self-administered the forced oscillation technique daily.

The patients with mild, intermittent asthma were to measure their inspiratory resistance variability, which was significantly more accurate than the PEF variability or the coefficient of variation of morning measurements (CVPEF) during a 2-week period.4 The inspiratory resistance mean accuracy rate was 0.91 (95% confidence interval [CI], 0.85-0.97) vs 0.57 for PEF variability (95% CI, 0.40-0.75; P<.001) and 0.51 for CVPEF (95% CI, 0.34-0.68; P<.001).4

“Despite its 60-year-long history, the FOT is gaining more attention in the last few years as an alternative diagnostic and monitoring technique to spirometry,” said Dr Gobbi. “The availability of new commercial devices, which incorporate data processing algorithms that allow the measurement of several new parameters of the lungs, have been shown to be more accurate in detecting anomalies both in the central and small airways.”

Summary and Clinical Applicability

Definitive diagnosis has been elusive in asthma, especially in children. Specialty societies recommend spirometry, fractional exhaled nitric oxide testing, and bronchodilator reversibility as first-line tests: However, clinicians have not always followed this paradigm, which has resulted in underdiagnosis and overdiagnosis of asthma.

References

1. Danvers L, Lo DKH, Gaillard EA. The role of objective tests to support a diagnosis of asthma in children [published online February 28, 2019]. Paediatr Respir Rev. doi:10.1016/j.prrv.2019.02.001

2. Looijmans-van den Akker I, van Luijn K, Verheij T. Overdiagnosis of asthma in children in primary care: a retrospective analysis. Br J Gen Pract. 2016;66(644):e152-e157.

3. Amaral R, Carneiro AC, Wandalsen G, Fonseca JA, Sole D. Control of allergic rhinitis and asthma test for children (CARATKids): validation in Brazil and cutoff values. Ann Allergy Asthma Immunol. 2017;118(5):551-556.

4. Gobbi A, Gulotta C, Suki B, et al. Monitoring of respiratory resistance in the diagnosis of mild-intermittent asthma [published online February 23, 2019]. Clin Exp Allergy. doi:10.1111/cea.13376