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The Work Productivity and Activity Impairment Questionnaire for Patients with Gastroesophageal Reflux Disease (WPAI-GERD)

Responsiveness to Change and English Language Validation

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Abstract

Background

A validated productivity questionnaire, the Work Productivity and Activity Impairment questionnaire for Gastroesophageal Reflux Disease (WPAIGERD), exists for Swedish patients with GERD.

Objective

To assess responsiveness to change of the WPAI-GERD and construct validity of the English language version.

Methods

We used the WPAI-GERD in a before-after treatment clinical study of Canadian GERD patients with moderate or severe symptoms treated with esomeprazole 40mg once daily for 4 weeks. We measured productivity variables including GERD-specific absence from work, reduced productivity while at work and reduced productivity while carrying out regular daily activities other than work during the preceding week.

Results

The analysis included 217 patients, of whom 71% (n = 153) were employed. Before treatment, employed patients reported an average 0.9 hours of absence from work due to GERD and 14.0% reduced work productivity (5.8 hours equivalent) in the previous week, as well as 21.0% reduced productivity in daily activities (all patients). After treatment, the corresponding figures decreased to 0.3 hours, 3.0% (1.1 hours equivalent) and 4.9%, respectively. Thus, the improvement (difference from start of treatment) in productivity was 0.6 hours (p = 0.011) for absence from work and 11.0% units (p < 0.001) for reduced work productivity (4.7 hours equivalent, p < 0.001). This translated into an avoided loss of work productivity of 5.3 hours in total on a weekly basis per employed patient. In addition, a 16.1% unit (p < 0.001) improvement for reduced productivity in activities was observed.

Cross-sectional correlation coefficients of WPAI variables with symptoms (range 0.04–0.63) and health-related quality of life (HR-QOL; range 0.02–0.65) supported cross-sectional construct validity. Corresponding change score correlations between WPAI variables and HR-QOL (range 0.0520.56) supported longitudinal construct validity of the WPAI-GERD while low change score correlations between productivity variables and relevant symptoms (range 0.06–0.34) did not.

Conclusion

The English version of the WPAI-GERD showed good cross-sectional construct validity, and results indicated that the WPAI-GERD is responsive to change. Although the results also indicated that longitudinal construct validity may be poor, the overall findings suggest that further study of the instrument remains warranted.

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References

  1. Vakil N, Rydén-Bergsten T, Bergenheim K. Systematic review: patient-centred endpoints in economic evaluations of gastroesophageal reflux disease. Aliment Pharmacol Ther 2002; 16: 1469–1480

    Article  PubMed  CAS  Google Scholar 

  2. Burton WN, Morrison A, Wertheimer AI. Pharmaceuticals and worker productivity loss: a critical review of the literature. J Occup Environ Med 2003; 45: 610–621

    Article  PubMed  Google Scholar 

  3. Prasad M, Wahlqvist P, Shikiar R, et al. A review of self-report instruments measuring health-related work productivity: a patient-reported outcomes perspective. Pharmacoeconomics 2004; 22 (4): 225–244

    Article  PubMed  Google Scholar 

  4. Dent J, El-Serag HB, Wallander MA, et al. Epidemiology of gastro-oesophageal reflux disease: a systematic review. Gut 2005; 54: 710–717

    Article  PubMed  CAS  Google Scholar 

  5. Kennedy T, Jones R. The prevalence of gastro-oesophageal reflux symptoms in a UK population and the consultation behaviour of patients with these symptoms. Aliment Pharmacol Ther 2000; 14: 1589–1594

    Article  PubMed  CAS  Google Scholar 

  6. Locke GR, Talley NJ, Fett SL, et al. Prevalence and clinical spectrum of gastroesophageal reflux: a population-based study in Olmsted County, Minnesota. Gastroenterology 1997; 112: 1448–1456

    Article  PubMed  Google Scholar 

  7. Spechler SJ. Epidemiology and natural history of gastro-oesophageal reflux disease. Digestion 1992; 51 Suppl. 1: S24–S29

    Article  Google Scholar 

  8. Tougas G, Chen Y, Hwang P, et al. Prevalence and impact of upper gastrointestinal symptoms in the Canadian population: findings from the DIGEST study. Am J Gastroenterol 1999; 94: 2845–2854

    Article  PubMed  CAS  Google Scholar 

  9. Penston JG, Pounder RE. A survey of dyspepsia in Great Britain. Aliment Pharmacol Ther 1996; 10: 83–89

    Article  PubMed  CAS  Google Scholar 

  10. Wiklund I. Quality of life in patients with gastroesophageal reflux disease. Am J Gastroenterol 2001;96 Suppl.: S46–S53

    Article  CAS  Google Scholar 

  11. Henke CJ, Levin TR, Henning JM, et al. Work loss costs due to peptic ulcer disease and gastroesophageal reflux disease in a health maintenance organization. Am J Gastroenterol 2000; 95: 788–792

    Article  PubMed  CAS  Google Scholar 

  12. Dean B, Aguilar D, Crawley JA, et al. Impact of gastroesophageal reflux disease on worker productivity in an employed US population [abstract]. Gastroenterology 2003; 124 Suppl. 1: A505

    Article  Google Scholar 

  13. Reilly Associates Health Outcomes Research [online]. Available from URL: http://www.reillyassociates.net/WPAI_GH.html [Accessed 2007 Mar 23]

  14. Reilly M, Tanner A, Meltzer EO. Work, classroom, and activity impairment instruments: validation studies in allergic rhinitis. Clin Drug Invest 1996; 11: 278–288

    Article  Google Scholar 

  15. Wahlqvist P, Carlsson J, Stålhammar N-O, et al. Validity of a work productivity and activity impairment questionnaire for patients with symptoms of gastro-esophageal reflux disease (WPAI-GERD): results from a cross-sectional study. Value Health 2002; 5: 106–113

    Article  PubMed  Google Scholar 

  16. Schunemann HJ, Armstrong D, Degl’Innocenti A, et al. A randomized multi-center trial to evaluate simple utility elicita-tion techniques in patients with gastroesophageal reflux disease. Med Care 2004; 42: 1132–1142

    Article  PubMed  Google Scholar 

  17. Reilly Associates Health Outcomes Research [online]. Available from URL: http://www.reillyassociates.net/WPAI_SHP.html [Accessed 2007 Mar 23]

  18. Ware JE, Snow KK, Kosinski MA. SF-36 health survey manual and interpretation guide. Boston (MA): New England Medical Centre, 1993

    Google Scholar 

  19. Talley NJ, Fullerton S, Junghard O, et al. Quality of life in patients with endoscopy-negative heartburn: reliability and sensitivity of disease-specific instruments. Am J Gastroenterol 2001; 96: 1998–2004

    Article  PubMed  CAS  Google Scholar 

  20. Fairclough DL, Cella DF. Functional assessment of cancer therapy (FACT-G): non-response to individual questions. Qual Life Res 1996; 5: 321–329

    Article  PubMed  CAS  Google Scholar 

  21. Hinkle DE, Jurs SG, Wiersma W. Applied statistics for the behavioral sciences. 2nd ed. Boston (MA): Houghton Mifflin, 1988

    Google Scholar 

  22. Curtin F, Schulz P. Multiple correlations and Bonferroni’s correction. Biol Psychiatry 1998; 44: 775–777

    Article  PubMed  CAS  Google Scholar 

  23. Brouwer W, Meerding W-J, Lamers L, et al. The relationship between productivity and health-related QOL. Pharmacoeconomics 2005; 23 (3): 209–218

    Article  PubMed  Google Scholar 

  24. Burke L, Piault E. Patient-reported measures in drug development: FDA perspective. In: Chassany C, Caulin C, editors. Health-related quality of life and patient-reported outcomes: scientific and useful outcome criteria. Paris: Springer-Verlag, 2003: 117–122

    Google Scholar 

  25. Cohen J. Statistical power analysis for the behavioral sciences. New York: Academy Press, 1977

    Google Scholar 

  26. Lerner D, Adler DA, Chang H, et al. The clinical and occupational correlates of work productivity loss among employed patients with depression. J Occup Environ Med 2004; 46 (6 Suppl.): S46–S55

    Article  Google Scholar 

  27. Dean BB, Crawley JA, Reeves JD, et al. The cost of gastroesophageal reflux disease: it’s what you don’t see that counts. J Managed Care Med 2003; 7: 6–13

    Google Scholar 

  28. Stewart WF, Ricci J, Leotta CR. Health-related lost productive time (LPT): recall interval and bias in LPT estimates. J Occup Environ Med 2004; 46: S12–S22

    Article  PubMed  Google Scholar 

  29. Wahlqvist P, Reilly M, Barkun A. Systematic review: the impact of gastro-oesophageal reflux disease on work productivity. Aliment Pharmacol Ther 2006; 24: 259–272

    Article  PubMed  CAS  Google Scholar 

  30. Koopmanschap M, Burdorf A, Jacob K, et al. Measuring productivity changes in economic evaluation: setting the research agenda. Pharmacoeconomics 2005; 23: 47–54

    Article  PubMed  Google Scholar 

  31. Torrance G, Feeny D, Furlong W. Visual analog scales: do they have a role in measurement of preferences for health states? Med Decis Making 2001; 21: 329–334

    PubMed  CAS  Google Scholar 

Download references

Acknowledgements

This study was funded by AstraZeneca R&D Mölndal, Sweden, which markets esomeprazole, a proton pump inhibitor for GERD. At the time of the study L. Tanser, A. Degl’Innocenti, P. Wahlqvist and I. Wiklund were employees of AstraZeneca and as such were eligible to receive stock options. H.J. Schünemann, N. Chiba, A. Barkun, S. Veldhuyzen van Zanten, C. Fallone, G. Guyatt and D. Armstrong have all either received grants or honoraria, or have consulted for AstraZeneca in the past 5 years. The funding received by G. Guyatt and H.J. Schünemann was institutional and not personal.

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Authors and Affiliations

  1. AstraZeneca R&D, S-431 83, Mölndal, Sweden

    Peter Wahlqvist, Alessio Degl’Innocenti & Ingela Wiklund

  2. McMaster University, Hamilton, Ontario, Canada

    Gordon H. Guyatt, David Armstrong, Diane Heels-Ansdell, Peggy Austin & Naoki Chiba

  3. University at Buffalo, State University of New York, Buffalo, New York, USA

    Samer El-Dika

  4. The McGill University Health Center, McGill University, Montreal, Quebec, Canada

    Carlo A. Fallone & Alan N. Barkun

  5. AstraZeneca Canada, Mississauga, Ontario, Canada

    Lisa Tanser

  6. Dalhousie University, Halifax, Nova Scotia, Canada

    Sander Veldhuyzen van Zanten

  7. Department of Epidemiology, Italian National Cancer Institute, Regina Elena, Rome, Italy

    Holger J. Schünemann

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  1. Peter Wahlqvist
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  2. Gordon H. Guyatt
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  4. Alessio Degl’Innocenti
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  7. Ingela Wiklund
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  9. Lisa Tanser
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  11. Peggy Austin
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  12. Alan N. Barkun
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  13. Naoki Chiba
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  14. Holger J. Schünemann
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Corresponding author

Correspondence to Peter Wahlqvist.

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Wahlqvist, P., Guyatt, G.H., Armstrong, D. et al. The Work Productivity and Activity Impairment Questionnaire for Patients with Gastroesophageal Reflux Disease (WPAI-GERD). Pharmacoeconomics 25, 385–396 (2007). https://doi.org/10.2165/00019053-200725050-00003

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  • DOI: https://doi.org/10.2165/00019053-200725050-00003

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