Clinical Cough IV:What is the Minimal Important Difference for the Leicester Cough Questionnaire?

  • A. A. Raj
  • D. I. Pavord
  • S. S. Birring
Part of the Handbook of Experimental Pharmacology book series (HEP, volume 187)

Abstract

Background: The Leicester Cough Questionnaire (LCQ) is a valid, reproducible, responsive self-reported cough-specific health status measure. It has been used to assess overall efficacy of treatments for cough, but its threshold for clinical significance, or patient importance, is unknown. The aim of this study was to determine the minimal important difference (MID) of the LCQ for patients with chronic cough; this is the smallest change in quality-of-life score considered to be clinically meaningful.

Methods: The LCQ MID was first estimated by a multidisciplinary panel of experts who reviewed two cases of chronic cough. It was subsequently determined using a standardized method. Fifty-two patients with chronic cough of more than 8 weeks' duration attending a respiratory outpatient clinic were recruited. Participants completed the LCQ at initial evaluation and repeated the LCQ with four Global Rating of Change Questionnaires (GRCQ) more than 2 months later. The LCQ total score ranges from 3 to 21 and from 1 to 7 for physical, psychological and social domains; a higher score indicates a better health-related quality of life. The GRCQ, a 15-point scale scored between +7 (a great deal better) and −7 (a great deal worse), was used to record patient ratings of change in cough symptoms. The MID was defined as the change in LCQ health status corresponding to a small change in the GRCQ score.

Results: The mean (standard deviation) LCQ MID corresponding to a small change in the GRCQ score was 1.3 (3.2); the MIDs for domains were as follows: physical 0.2 (0.8), social 0.2 (1.1) and psychological 0.8 (1.5). This MID for LCQ total score was similar to that determined by the expert panel. The global rating of change scores correlated significantly with the change in LCQ total and domain scores (r = 0.4−0.5; p < 0.005).

Conclusion: We have demonstrated that the LCQ MID is 1.3. The LCQ MID should aid clinicians and researchers to make meaningful interpretations of healthrelated quality-of-life data relating to chronic cough.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Beaton DE, Boers M, Wells GA (2002) Many faces of the minimal clinically important difference (MCID): A literature review and directions for future research. Curr Opin Rheumatol 14: 109–114PubMedCrossRefGoogle Scholar
  2. Birring SS, Prudon B, Carr AJ et al (2003) Development of a symptom specific health status measure for patients with chronic cough: Leicester cough questionnaire (LCQ). Thorax 58:339–343PubMedCrossRefGoogle Scholar
  3. Brightling CE, Ward R, Goh VV et al (1999) Eosinophilic bronchitis is an important cause of cough. Am J Respir Crit Care 160:406–410Google Scholar
  4. Decalmer S, Webster D, Kelsall A, McGuinness K, Woodcock A, Smith A (2007) Chronic cough: How do cough reflex sensitivity and subjective assessments correlate with objective cough counts during ambulatory monitoring? Thorax 62:329–334PubMedCrossRefGoogle Scholar
  5. French CT, Irwin RS, Fletcher KE et al (2002) Evaluation of a cough-specific quality-of-life questionnaire. Chest 121:1123–1131PubMedCrossRefGoogle Scholar
  6. Guyatt GH, Berman LB, Townsend M et al (1987) A measure of quality of life for clinical trials in chronic lung disease. Thorax 42:773–778PubMedGoogle Scholar
  7. Guyatt GH, Nogradi S, Halcrow VV et al (1989) Development and testing of a new measure of health status for clinical trials in heart failure. J Gen Intern Med 4:101–107PubMedCrossRefGoogle Scholar
  8. Guyatt GH, Norman GR, Juniper EF, Griffith LE (2002a) A critical look at transition ratings. J Clin Epidem 55:900–908CrossRefGoogle Scholar
  9. Guyatt GH, Osoba D, Wu AW, Wyrwich KW, Norman GR (2002b) Methods to explain the clinical significance of health status measures. Mayo Clin Proc 77:371–383Google Scholar
  10. Jaeschkle R, Singer J, Guyatt GH (1989) Measurements of health status: Ascertaining the minimally clinically important difference. Control Clin Trials 10:407–415CrossRefGoogle Scholar
  11. Jones PW (2002) Interpreting thresholds for a clinically significant change in health status in asthma and COPD. Eur Respir J 19:398–404PubMedCrossRefGoogle Scholar
  12. Jones PW, Quirk FH, Baveystock CM (1991) The St George's Respiratory Questionnaire. Respir Med 85:25–31PubMedCrossRefGoogle Scholar
  13. Juniper EF, Guyatt GH, Willan A et al (1994) Determining a minimal important change in a disease-specific quality of life questionnaire. J Clin Epidemiol 47:81–87PubMedCrossRefGoogle Scholar
  14. McGarvey LPA, Heaney LG, MacMahon J (1998) A retrospective survey of diagnosis and management of patients presenting with chronic cough to a general chest clinic. Int J Clin Pract 52:158–161PubMedGoogle Scholar
  15. Morice AH, Menon MS, Mulrennan SA et al (2007) Opiate therapy in chronic cough. Am J Respir Crit Care Med 175:312–315PubMedCrossRefGoogle Scholar
  16. Redelmeier DA, Guyatt GH, Goldstein RS (1996) Assessing the minimal important difference in symptoms: A comparison of two different techniques. J Clin Epidemiol 49:1215–1219PubMedCrossRefGoogle Scholar
  17. Wyrwich KW, Tierry WM (2002) Using the standard error of measurement to identify important changes in the asthma quality of life questionnaire. Qual Life Res 11:1–7PubMedCrossRefGoogle Scholar
  18. Wyrwich KW, Nienaber NA, Tierney WM, Wolinsky FP (1999) Linking clinical relevance and statistical significance in evaluating intra-individual changes in health-related quality of life. Med Care 37:469–478PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • A. A. Raj
    • 1
  • D. I. Pavord
    • 1
  • S. S. Birring
    • 1
  1. 1.Department of Respiratory MedicineKing's College HospitalLondonUK

Personalised recommendations