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Assessment and Management of Chronic Cough

Comparative Effectiveness Reviews, No. 100

Investigators: , MD, MHS, , MD, PhD, , MD, MHSc, , MD, MPH, , MD, MPH, MS, , PT, DPT, PhD, , PhD, , PhD, , MCM, , , DPhil, and , PhD.

Duke Evidence-based Practice Center
Rockville (MD): Agency for Healthcare Research and Quality (US); .
Report No.: 13-EHC032-EF

Structured Abstract

Objectives:

Cough is the most common complaint for patients seeking medical attention in the United States. Although the most common cause of cough is acute self-limited viral infections, chronic cough (cough that lasts more than 4 weeks in children <14 years of age or more than 8 weeks in adolescents and adults) has a significant impact on quality of life and is responsible for up to 38 percent of pulmonary outpatient visits. Furthermore, a treatable cause is absent in up to 46 percent of patients with chronic cough despite a thorough diagnostic investigation. The comparative value of tools for assessing cough and the comparative effectiveness of treatments for unexplained or refractory cough are uncertain.

Data sources:

We searched PubMed®, Embase®, and the Cochrane Database of Systematic Reviews (June 4, 2012) for relevant English-language comparative studies.

Review methods:

Two investigators screened each abstract and full-text article for inclusion, abstracted data, rated quality and applicability, and graded evidence. Random-effects models were used to compute summary estimates of effects. We supplemented the meta-analysis of direct comparisons with a mixed treatment meta-analysis that incorporated data from placebo comparisons and head-to-head comparisons.

Results:

To evaluate instruments for assessing cough, we considered the dimensions of cough frequency, cough severity, and cough-specific quality of life (QOL). We sought to measure the validity, reliability, and responsiveness of various instruments used to assess each of these dimensions. Seventy-eight studies (5,927 subjects) evaluated instruments for assessing cough. The Leicester Cough Questionnaire (LCQ) and Cough-specific Quality of Life Questionnaire (CQLQ) were the most widely studied instruments in adults; there is moderate strength of evidence (SOE) to support both the LCQ's and the CQLQ's validity in assessing severity/QOL of cough. For pediatric populations, there is moderate SOE to support the Parent Cough-specific Quality of Life questionnaire's (PC-QOL) validity in assessing severity/QOL of cough. Electronic recording devices are accurate for assessing cough frequency, but show variable correlation with other tools. Although visual analog scales (VAS) are easy to administer and have face validity, we did not identify any studies to formally validate their accuracy in assessing cough. We identified no studies exploring the impact of cough assessment instruments on therapeutic efficacy or patient outcome efficacy.

Forty-eight studies (2,923 patients) evaluated 67 therapeutic comparisons for patients with chronic cough. Classes of drugs evaluated included opioid, anesthetic, and nonopioid/nonanesthetic antitussives; expectorant and mucolytic protussives; antihistamines; antibiotics; inhaled corticosteroids; and inhaled anticholinergics. The opioid and certain nonopioid/nonanesthetic antitussives most frequently demonstrated efficacy for managing chronic cough in adults. In particular, codeine and dextromethorphan reduced cough severity and frequency. Relative to placebo, the effect of dextromethorphan on cough severity was 0.54 (95% confidence interval [CI], 0.27 to 0.80; p=0.0008), and the effect of opiates was 0.63 (95% CI, 0.40 to 0.86; p<0.0001). Relative to placebo, the effect of dextromethorphan on cough frequency was 0.40 (95% CI, 0.18 to 0.85; p=0.0248), and the effect of codeine was 0.57 (95% CI, 0.36 to 0.91; p=0.0260). However, due to inconsistency and imprecision of results, and small numbers of direct comparisons, the overall SOE is insufficient to draw firm conclusions about the comparative effectiveness of these agents. Very few studies evaluated nonpharmacological therapies (two studies) or the management of cough in children (three studies).

Conclusions:

Several instruments for assessing cough severity, frequency, and impact on cough-specific quality of life show good internal consistency but variable correlation with other cough measurement tools, meaning that a number of instruments are precise but their accuracy is less clear. Although the evidence is sparse, the opioid and certain nonopioid/nonanesthetic antitussives most frequently demonstrated efficacy for managing the symptom of chronic cough in adults. Our review highlights the need for further studies in patient populations with unexplained or refractory chronic cough as determined by current diagnostic and empiric treatment recommendations. Further, it shows the need for more systematic design and reporting of these studies and assessment of their patient-centered outcomes. This is in contrast to the more extensive literature on the management of acute cough.

Contents

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Errata March 2014: Table A in the Executive Summary and Tables 6, 11, and 12 in the full report have been updated to reflect the following changes: 1. CQLQ--corrected sample size and correlation coefficients for French 2002 paper for Internal Consistency; 2. CQLQ--corrected sample size and correlation coefficients for French 2002 paper for Repeatability; 3. PC-QOL--added data from Newcombe 2010 study for Repeatability. The text and conclusions remain unchanged.

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services1, Contract No. 290-2007-10066-I. Prepared by: Duke Evidence-based Practice Center, Durham, NC

Suggested citation:

McCrory DC, Coeytaux RR, Yancy WS Jr., Schmit KM, Kemper AR, Goode A, Hasselblad V, Heidenfelder BL, Irvine RJ, Musty MD, Gray R, Sanders GD. Assessment and Management of Chronic Cough. Comparative Effectiveness Review No. 100. (Prepared by the Duke Evidence-based Practice Center under Contract No. 290-2007-10066-I.) AHRQ Publication No. 13-EHC032-EF. Rockville, MD: Agency for Healthcare Research and Quality; January 2013. Errata March 2014. www.effectivehealthcare.ahrq.gov/reports/final.cfm.

This report is based on research conducted by the Duke Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-2007-10066-I). The findings and conclusions in this document are those of the authors, who are responsible for its contents; the findings and conclusions do not necessarily represent the views of AHRQ. Therefore, no statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help health care decisionmakers—patients and clinicians, health system leaders, and policymakers, among others—make well-informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information, i.e., in the context of available resources and circumstances presented by individual patients.

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

None of the investigators have any affiliations or financial involvement that conflicts with the material presented in this report.

1

540 Gaither Road, Rockville, MD 20850; www​.ahrq.gov

Bookshelf ID: NBK116707PMID: 23367526
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