Quality of life in relation to constipation among opioid users

Abstract

Objective: Opioid users often experience constipation. In this study the impact of constipation on QoL was assessed in patients using opioids either for non-advanced illness or advanced illness.

Methods: Patients using opioids, recruited via public pharmacies, were asked to complete questionnaires on opioid use, constipation and the EuroQol five-dimension questionnaire (EQ-5D). Patients with a severe non-curable disease and relatively short life-expectancy were classified as having an advanced illness; a disabling yet not directly life-threatening condition was defined as non-advanced illness. Constipation was assessed based on questions on opioid side-effects and laxative use. EQ-5D index scores were compared between patients with and without constipation using Wilcoxon two-samples test.

Results: Questionnaires were returned by 588 patients with non-advanced illness, of whom 326 (55%) were classified as having constipation and by 113 patients with advanced illness, of whom 76 (67%) were classified as having constipation. The median EQ-5D index, a weighted health state index score with 1 = full health, was lower in patients with constipation than in patients without constipation (0.31 vs. 0.65, p< 0.01 for non-advanced illness and 0.41 vs. 0.61, p=0.12 for advanced illness).

Conclusion: The results of this study suggest that, in patients using opioids either for non-advanced illness or advanced illness, constipation negatively influences QoL. By separately analysing patients with advanced illness and patients with non-advanced illness, possible selective non-response and confounding was accounted for, but not completely solved.

Key words::

• constipation
• opioid
• quality of life
• questionnaires

Transparency

Declaration of funding: This study was financially supported by an unrestricted grant from Wyeth Pharmaceuticals BV, Hoofddorp, The Netherlands. No limitations were set with regard to the conduct of the study and the writing of the manuscript. Wyeth is now a part of Pfizer, Inc., the merger of local entities may be pending and is subject to full local regulatory approval.

Declaration of financial/other relationships: F.J.A. Penning-van Beest. P. van den Haak and R.M.C. Herings have disclosed that they are employees of the PHARMO Institute, which receives grants from several pharmaceutical companies, including Wyeth. R.M. Klok and Y.F.D.M. Prevoo have disclosed that they are employees of Wyeth Pharmaceuticals BV.

The JME peer reviewers 1 and 2 have not received an honorarium for their review work on this manuscript. Both have disclosed that they have no relevant financial relationships.

Acknowledgements: The authors would like to thank M.W. van der Linden for his work in the design and conduct of the study.

In addition, the results have been presented on a poster at the 11th Annual European Congress of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR, 8–11 November 2008, Athens, Greece).