Quality of life benefits and cost impact of prolonged release oxycodone/naloxone versus prolonged release oxycodone in patients with moderate-to-severe non-malignant pain and opioid-induced constipation: a UK cost-utility analysis

Abstract

Objective:

To compare the cost effectiveness of prolonged release oxycodone/naloxone (OXN) tablets (Targinact) and prolonged release oxycodone (OXY) tablets (OxyContin) in patients with moderate-to-severe non-malignant pain and opioid-induced constipation (OIC) from the perspective of the UK healthcare system.

Methods:

A cohort model used data from a phase III randomised, controlled trial (RCT). It calculated the cost difference between treatments by combining the cost of pain therapy with costs of laxatives and other resources used to manage constipated patients. SF-36 scores were converted into EQ-5D utility values to calculate the quality-adjusted life-year (QALY) gains. Deterministic and probabilistic sensitivity analyses were performed.

Results:

The incremental cost of OXN versus OXY was £159.68 for the average treatment duration of 301 days. OXN gave an incremental QALY gain of 0.0273. The estimated incremental cost-effectiveness ratio (ICER) was £5841.56 per QALY. Sensitivity analyses gave a maximum ICER of £10,347.03. In some scenarios, OXN dominated with a cost saving of up to £4254.70. Probabilistic sensitivity analysis showed that OXN had approximately 96.6% probability of cost effectiveness at the £20,000 threshold.

Limitations:

The model was conservative in predicting the probability of constipation beyond the 12-week RCT period. UK cost of constipation data were limited and based on primary care physician opinion.

Conclusions:

In the base case, direct treatment costs were slightly higher for patients treated with OXN than for those treated with OXY. However, patients treated with OXN experienced a quality of life gain, and had an ICER considerably below thresholds commonly applied in the UK. The model was most sensitive to the estimated cost of constipation with a number of realistic scenarios in the sensitivity analysis demonstrating a cost saving with OXN (OXN dominant). OXN is therefore estimated to be a cost-effective option for treating patients with severe non-malignant pain and OIC.

Keywords::

• Bowel function index
• Cost-utility analysis
• Naloxone
• Opioid-induced constipation
• Oxycodone
• Pain

Transparency

Declaration of funding

This cost-utility study was sponsored by Napp Pharmaceuticals Limited.

Declaration of financial/other relationships

At the time of the study, W.D. was an employee of Napp Pharmaceuticals Limited; he is currently an employee of Mundipharma International Limited. R.U. is an employee of Mundipharma Research GmbH & Co. KG. I.K. is an employee of Mundipharma Research Limited. A.T. is an employee of Napp Pharmaceuticals Limited. Napp Pharmaceuticals Limited, Mundipharma Research GmbH & Co. KG, Mundipharma Research Limited and Mundipharma International Limited are independent associated companies. G.B. is employed by the University of East Anglia (UEA). UEA Consulting Limited received funding from Napp Pharmaceuticals Limited in order to critically appraise the model outlined in this paper.

Acknowledgements

Itrat Iqbal (Napp Pharmaceuticals Limited) provided support with the economic analyses. Dr Joanna Todd and Iain Leslie (Napp Pharmaceuticals Limited) provided medical writing services.

Notes

*[Targinact, Napp Pharmaceuticals, Cambridge, UK]

†[OxyContin, Purdue Pharma LP, Stamford, CT, USA]

*Exchange rates taken from http://www.xe.com. $1 US = £0.615574023 (2nd March 2011). €1 = £0.887653 (10th June 2011)