Over- and under-diagnosis in asthma

Asthma is extremely common with a prevalence of approximately 10% in Europe. It presents with symptoms which have a broad differential diagnosis and examination can be entirely normal. There is no agreed gold standard to diagnose asthma, and the objective tests that can aid diagnosis are often poorly available to primary care physicians. There is evidence that asthma is widely misdiagnosed. Overdiagnosis leads to unnecessary treatment and a delay in making an alternative diagnosis. Underdiagnosis risks daily symptoms, (potentially serious) exacerbations and long-term airway remodelling. An agreed standardised approach to diagnosis, with inclusion of objective measurements prior to treatment, is required to reduce misdiagnosis of asthma. KEY POINTS: Asthma presents with common respiratory symptoms and physical examination is often normal; in addition, the most widely available tests (peak flow and spirometry) can be normal unless the patient is exacerbating. Treating asthma prior to carrying out objective tests decreases their sensitivity and can make confirmation of the diagnosis difficult. There is no single gold standard test to diagnose asthma, and there are significant differences between the suggested algorithms in commonly used guidelines. Both under- and over-diagnosis are widespread and lead to significant risks to patients.