(Courtesy U.S. NIH,: National Heart, Lung, Blood Institute [Public domain], via Wikimedia Commons)

More than 1.2 million people in the U.K. may have been wrongly diagnosed with asthma and may be taking unnecessary medications, according to a new draft clinical guideline for asthma diagnosis.

The National Institute for Health and Care Excellence (NICE) said up to 30 percent of 4.1 million adults who are treated for asthma in the United Kingdom do not have clear evidence of the chronic condition, although some might have had it once.

About 235 million people worldwide suffer from asthma, according an estimate by the World Health Organization (WHO). Yet asthma remains under-studied, under-diagnosed and under-treated, and creates a significant burden on patients, their families and the health care systems.

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TRIGGERS OF ASTHMA

• Indoor allergens (dust mites, pollution, pet dander)
• Outdoor allergens (pollens, molds)
• Cockroach allergens
• Tobacco smoke
• Workplace chemical irritants
• Air pollution
• Respiratory infections
• Cold air
• Physical activity
• Stress and strong emotions
• Sulfites and preservatives

(Sources: WHO, CDC, Mayo Clinic)

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Prof. Mark Baker, director of clinical practice at NICE, acknowledged that under-diagnosis is a concern along with misdiagnosis:

 Accurate diagnosis of asthma has been a significant problem which means that people may be wrongly diagnosed or cases might be missed in others. Our aim with this guideline is to give clarity and set out the most clinical and cost effective ways to diagnose and monitor asthma based on the best available evidence.

The 315-page draft guideline stresses that signs and symptoms alone are insufficient for an accurate diagnosis and recommends spirometry as the go-to clinical tool to check for obstructive airway disease.

The clinical guideline summarizes differential diagnosis in four flow charts that refers suspected occupational asthma to a specialist and recommends spirometry for those who are five and older.

Use spirometry as the first-line investigation for asthma in adults and young people older than 16 and children aged 5-16 years. Regard a forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio of less than 70% as a positive test for obstructive airway disease (obstructive spirometry).

For those with obstructive spirometry, the watchdog recommends a bronchodilator reversibility (BDR) test to see if FEV1 improves by 12% or more and if the volume increases by 200 mL or more.

In the United States, 18.7 million adults and 6.8 million children live with asthma, according to the Centers for Disease Control and Prevention. Asthma kills an estimated 3,345 people in the U.S. each year.