There are little data on the usefulness of different tests to diagnose asthma in children.
We assessed the contribution of a detailed history and a variety of diagnostic tests for diagnosing asthma in children.
We studied children aged 6-16 years referred consecutively for evaluation of suspected asthma to two pulmonary outpatient clinics in Basel and St. Gallen. Symptoms were assessed by parental questionnaire. The clinical evaluation included skin prick tests, measurement of fractional exhaled nitric oxide (FeNO), spirometry, bronchodilator reversibility and bronchial provocation tests (BPT) by exercise, methacholine, and mannitol. Asthma was diagnosed by the physicians at the end of the visit. We assessed diagnostic accuracy of symptoms and tests by calculating sensitivity, specificity, positive and negative predictive values, and area under the curve (AUC).
Of the 111 participants, 80 (72%) were diagnosed with asthma. The combined sensitivity and specificity (sensitivity/specificity) was highest for reported frequent wheeze (>3 attacks/year) (0.44/0.90), awakening due to wheeze (0.41/0.90), and wheeze triggered by pollen (0.46/0.83) or by pets (0.29/0.99). Of the diagnostic tests, the AUC was highest for FeNO measurement (0.80) and BPT by methacholine (0.81) or exercise (0.74), and lowest for FEV1 (0.62) and FEV1/FVC (0.66), assessed by spirometry.
This study suggests that specific questions about triggers and severity of wheeze, and measurement of FeNO and BPT by methacholine or exercise contribute more to the diagnosis of asthma in school-aged children than spirometry, bronchodilator reversibility and, skin prick tests and other BPTs.
This research was funded by Swiss National Science Foundation: 32003B_162820, AstraZeneca (Switzerland), the Lung League St. Gallen and the Schmidheiny Foundation (Heerbrugg, St. Gallen).
