1 Cough for at least 8 weeks without wheezing. No wheezing on auscultation of chest
2 No past history of asthma symptoms such as wheezing or dyspnoea
3 No history of upper respiratory infection within previous 8 weeks
4 Increased airway responsiveness†
5 Effective response to bronchodilator therapy‡
6 No increase in cough sensitivity§
7 No abnormal findings on CXR
†Reference values for increased airway responsiveness: Dmin <12.5 units, PC20-FEV1 <10 mg/dL with methacholine.‡ Evaluate response to bronchodilator therapy using oral or inhaled β2 agonists. Use of an objective parameter (e.g. VAS, symptom score) is preferable.§ Cough
sensitivity is not increased in some reports and decreases with treatment in other reports, but in pure cough-variant asthma there is no increase. The issue of cough sensitivity is currently under review.
Some studies suggest that peripheral airway obstruction plays a role. In some cases, decreases in FEV1 and FEV1/FVC have been reported.
Table 3: Diagnostic criteria for cough-variant asthma (must meet all criteria 1–7)