Future directions in the clinical management of cough: ACCP evidence-based clinical practice guidelines.

OBJECTIVES: To impart a call for further research into the identified domains of particular interest in the etiology, management, and treatment of cough.

DESIGN/METHODOLOGY: A literature review was performed using the search term "cough" in PubMed between 1983 and 2004. The final draft of this guideline was reviewed, in addition to recent studies on cough, and suggestions provided by the authors were collated into a definitive inventory of specific areas in which the lack of quality evidence encumbered the development of clinically relevant evidence-based recommendations.

RESULTS/CONCLUSIONS: Although our understanding of the causes and optimal management of chronic cough have significantly increased over the past 25 years, further research remains to be done on this common symptom. This is reflected by the generally low level of evidence for many of the recommendations in these guidelines. Research is particularly needed on the optimal treatment of postinfectious cough, how to distinguish acute bronchitis from other conditions, how to reliably diagnose and treat cough due to gastroesophageal reflux disease, clearly identifying a role for nonpharmacologic protussive treatment modalities in diseases associated with an increased production of bronchial secretions, determining how often cough in patients with interstitial lung disease is due to conditions other than these, establishing the spectrum and frequency of causes of chronic cough in the immunocompromised hosts, and better characterizing psychogenic cough. Further studies are also needed on methods for the assessment of cough, in particular, noninvasive measures of airway inflammation, and pharmacotherapy. It should be determined how often unexplained cough (previously referred to as idiopathic cough) is due to the use of non-evidence-based guidelines or to environmental causes, and assessed whether an empiric, integrative approach of diagnosing chronic cough leads to better outcomes, including cost-effectiveness, than routine testing. While much work has been done on chronic cough, we need studies on the spectrum and frequency of acute and subacute coughs.