Rimonabant for the treatment of overweight and obese people

Abstract

This paper presents a summary of the evidence review group (ERG) report into the clinical and cost-effectiveness of rimonabant for the treatment of obese or overweight patients based upon a review of the manufacturer’s submission to the National Centre for Health and Clinical Excellence (NICE) as part of the single technology appraisal (STA) process. The submission’s main evidence came from four randomised controlled trials. Rimonabant resulted in a significantly greater benefit than placebo for all primary weight loss outcomes. At 1 year, rimonabant had a statistically significant beneficial effect on systolic blood pressure, high-density lipoprotein cholesterol, triglycerides and fasting plasma glucose in diabetics and non-diabetics, and glycosylated haemoglobin in diabetics. Improvements were maintained over 2 years with rimonabant; withdrawal of rimonabant at 1 year resulted in a reduction in weight loss until there was no difference from placebo at 2 years. Psychiatric adverse events were experienced by 26% and 14% of rimonabant and placebo patients respectively; figures for symptoms of depression were 9% and 5% respectively. Pairwise comparisons of orlistat, sibutramine and rimonabant showed beneficial effects of rimonabant over orlistat and sibutramine for weight loss outcomes; however, response hurdles imposed on orlistat or sibutramine in clinical practice may not have been applied in the orlistat and sibutramine trials. The manufacturer’s Markov cohort model evaluated rimonabant versus orlistat, sibutramine and diet and exercise alone for three base-case populations. The incremental cost-effectiveness ratio (ICER) of rimonabant varied from £10,534–£13,236 per quality-adjusted life-year (QALY) versus diet and exercise, to £8977–£12,138 per QALY versus orlistat, to £1463–£3908 per QALY versus sibutramine. In subgroup analysis there was a wider variation in the ICER estimates although none exceeded £20,000 per QALY. The ICER of rimonabant remained under £20,000 per QALY in reanalyses by the manufacturer and the ERG, with the results sensitive to the source of health-related quality of life (HRQoL) benefits in the model. Four treatment strategies were modelled in comparisons of rimonabant versus diet and exercise alone and orlistat and sibutramine in which rimonabant was continued only in patients achieving 5% weight loss at 3, 6, 9 or 12 months. In pairwise comparisons rimonabant remained below a threshold of £30,000 per QALY in 70% of the comparisons reported. The results were most sensitive to the decrement applied to depression and the costs of screening for depression. In conclusion, areas of uncertainty remain in relation to the clinical effectiveness and cost-effectiveness of rimonabant, for example lack of evidence on long-term outcomes and the effect of rimonabant on cardiovascular events, developing diabetes and mortality, and lack of data on the HRQoL benefits associated with rimonabant. The lack of response hurdles applied to sibutramine and orlistat means that the comparator strategies were not considered by the ERG to reflect their respective product licenses or current NHS use. The NICE guidance issued as a result of the STA states that rimonabant is recommended as an adjunct to diet and exercise for adults who are obese or overweight and who have had an inadequate response to, are intolerant of or are contraindicated to orlistat and sibutramine.