[Changes in the spectrum and frequency of causes for chronic cough: a retrospective analysis].

OBJECTIVE To investigate the changing patterns of the spectrum and frequency of causes for chronic cough, and to explore its clinical implications. METHODS Nine hundred and forty patients consecutively referred to Department of Respiratory Medicine for evaluation of chronic cough between January 2004 and December 2008 were collected and divided into 5 groups by periods of 5 years. The causes of cough had been primarily evaluated according to a step-by-step protocol and confirmed by the specific therapy. The changes in spectrum and frequency of causes were retrospectively analyzed by chi2 test. RESULTS The common causes of chronic cough were cough variant asthma (n = 437, 46%), upper airway cough syndrome/postnasal drip syndrome (n = 304, 32%), eosinophilic bronchitis (n = 87, 9%), gastroesophageal reflux-related chronic cough (n = 83, 9%), postinfectious cough (n = 60, 6%) and angiotensin-converting enzyme inhibitors-induced cough (n = 46, 5%) in descending order. There were significant differences in the distribution and frequency of etiologies when analyzed by year (chi2 = 60.6, P = 0.0001). During a 5-year period, chronic cough due to cough variant asthma increased from 44% to 51% (chi2 = 12.8, P = 0.010), upper airway cough syndrome/postnasal drip syndrome decreased from 49% to 29% (chi2 = 20.1, P = 0.001), and gastroesophageal reflux increased from 2% to 10% (chi2 = 17.6, P = 0.002). However, chronic cough associated with eosinophilic bronchitis, postinfection and angiotensin-converting enzyme inhibitors remained stable. CONCLUSION The common causes of chronic cough vary with time, which may have an impact on the strategy for the management of chronic cough.