A systematic review and economic evaluation of epoetin alpha, epoetin beta and darbepoetin alpha in anaemia associated with cancer, especially that attributable to cancer treatment.

OBJECTIVES

To assess the effectiveness and cost-effectiveness of epoetin alpha, epoetin beta and darbepoetin alpha (referred to collectively in this report as epo) in anaemia associated with cancer, especially that attributable to cancer treatment.

DATA SOURCES

Electronic databases were searched from 2000 (1996 in the case of darbepoetin alpha) to September 2004.

REVIEW METHODS

Using a recently published Cochrane review as the starting point, a systematic review of recent randomised controlled trials (RCTs) comparing epo with best standard was conducted. Inclusion, quality assessment and data abstraction were undertaken in duplicate. Where possible, meta-analysis was employed. The economic assessment consisted of a systematic review of past economic evaluations, an assessment of economic models submitted by the manufacturers of the three epo agents and development of a new individual sampling model (the Birmingham epo model).

RESULTS

In total 46 RCTs were included within this systematic review, 27 of which had been included in the Cochrane systematic review. All 46 trials compared epo plus supportive care for anaemia (including transfusions), with supportive care for anaemia (including transfusions), alone. Haematological response (defined as an improvement by 2 g/dl(-1)) had a relative risk of 3.4 [95% confidence interval (CI) 3.0 to 3.8, 22 RCTs] with a response rate for epo of 53%. The trial duration was most commonly 16-20 weeks. There was little statistical heterogeneity in the estimate of haematological response, and there were no important differences between the subgroups examined. Haemoglobin (Hb) change showed a weighted mean difference of 1.63 g/dl(-1) (95% CI 1.46 to 1.80) in favour of epo. Treatment with erythropoietin in patients with cancer-induced anaemia reduces the number of patients who receive a red blood cell transfusion (RBCT) by an estimated 18%. Health-related quality of life (HRQoL) data were analysed using vote counting and qualitative assessment and a positive effect was observed in favour of an improved HRQoL for patients on epo. Published information on side-effects was of poor quality. New trials provided further evidence of side-effects with epo, particularly thrombic events, but it is still unclear whether these could be accounted for by chance alone. The results of the previous Cochrane review had suggested a survival advantage for epo (HR 0.84, 95% CI 0.69 to 1.02), based on 19 RCTs. The update, based on 28 RCTs, suggests no difference (HR 1.03, 95% CI 0.88 to 1.21). Subgroup analysis suggested some explanations for this heterogeneity, but it is difficult to draw firm conclusions without access to the substantial amounts of missing or unpublished data, or more detailed results from some of the trials with heterogeneous patient populations. The conclusions are, however, broadly in line with those of a Food and Drug Administration (FDA) safety briefing, which recommended that patients with a haemoglobin above 12 g/dl(-1) should not be treated; the target rate of rise in Hb should not be too great, and further carefully conducted trials are required to determine which subgroups of patients may be harmed by the use of these products, in particular through the stimulation of tumour activity. Five published economic evaluations identified from the literature had inconsistent results, with estimates ranging from a cost per quality-adjusted life-year (QALY) under pound 10,000 through to epo being less effective and more costly than standard care. The more favourable evaluations assumed a survival advantage for epo. The three company models submitted each relied on assumed survival gains to achieve relatively low cost per QALY, from pound 13,000 to pound 28,000, but generated estimates from pound 84,000 to pound 159,000 per QALY when no survival gain was assumed. Each of these models relied on Hb levels alone driving utility, and each assumed gradual normalisation of Hb in the standard treatment arm after the end of treatment. The Birmingham epo model followed the company models in regard to the relationship between Hb levels and utility, and also assumed normalisation in the base case. With no survival gain, the incremental cost per QALY was pound 150,000, falling to pound 40,000 when the lower, more favourable, confidence interval for survival was used.

CONCLUSIONS

Epo is effective in improving haematological response and reducing RBCT requirements, and appears to have a positive effect on HRQoL. The incidence of side-effects and effects on survival remains highly uncertain. However, if there is no impact on survival, it seems highly unlikely that epo would be considered a cost-effective use of healthcare resources. The main target for further research should be improving estimates of impact on survival, initially through more detailed secondary research, such as the individual patient data meta-analysis started by the Cochrane group. Further trials may be required, and have been recommended by the FDA, although many trials are in progress, completed but unreported or awaiting mature follow-up. The Birmingham epo model developed as part of this project contains new features that improve its flexibility in exploring different scenarios; further refinement and validation would therefore be of assistance. Finally, further research to resolve uncertainty about other parameters, particularly quality of life, adverse events, and the rate of normalisation, would also be beneficial.