Cost Effectiveness of Naloxegol for Opioid-Induced Constipation in the UK

Richard Lawson, James Ryan, Frederic King, Jo Wern Goh, Eszter Tichy, Kevin Marsh

Opioid-induced constipation (OIC) is the most common adverse effect reported in patients receiving opioids to manage pain. Initial treatment with laxatives provides inadequate response in some patients. Naloxegol is a peripherally acting µ-opioid receptor antagonist used to treat patients with inadequate response to laxative(s) (laxative inadequate responder [LIR]). A cost-effectiveness model was constructed from the UK payer perspective to compare oral naloxegol 25 mg with placebo in non-cancer LIR patients receiving opioids for chronic pain, and a scenario analysis of naloxegol 25 mg with rescue laxatives compared with placebo with rescue laxatives in the same patient population. The model comprised a decision tree for the first 4 weeks of treatment, followed by a Markov model with a 4-week cycle length and the following states: 'OIC', 'non-OIC (on treatment)', 'non-OIC (untreated)' and 'death'. Two phase III trials with a follow-up period of 12 weeks provided data on treatment efficacy, transition probabilities, adverse event frequency and patient utility. Resource utilisation data were sourced from a UK-based burden of illness study and physician surveys. A UK National Health Service and Personal Social Service perspective was adopted; costs and health-related quality of life gains were discounted at a rate of 3.5 %. The model was run over a time horizon of 5 years, reflecting the average period of opioid use. Naloxegol has an incremental cost-effectiveness ratio of £10,849 per quality-adjusted life-year gained versus placebo, and £11,179 when rescue laxatives are made available in both arms (2014 values). Model outcomes were only sensitive to variations in utility inputs. However, the probabilistic sensitivity analyses indicate that naloxegol has a 91 % probability of being cost effective at a £20,000 threshold when compared with placebo. Naloxegol is likely a cost-effective treatment option for LIR patients with OIC. This assessment should be supported by further work on the utility of patients with OIC, including how utility varies with more granular measures of OIC.