Modelling the cost effectiveness of rituximab in chronic lymphocytic leukaemia in first-line therapy and following relapse.

BACKGROUND: The efficacy and safety of adding rituximab to fludarabine and cyclophosphamide (R-FC) for the treatment of chronic lymphocytic leukaemia (CLL) has been demonstrated in two randomised trials: CLL-8 was conducted in previously untreated patients, and REACH was conducted in previously treated patients. In both trials, progression-free survival was increased in the R-FC treatment groups compared with the FC treatment groups. In CLL-8, overall survival was also significantly increased.

OBJECTIVE: To develop an economic model to assess the cost effectiveness, from the Australian healthcare perspective, of rituximab when used as a treatment for both previously untreated and relapsed/refractory CLL.

METHODS: A Markov model with three health states (unprogressed, progressed and death) was developed to extrapolate the trial results over a 15-year time horizon. A treatment algorithm was developed with Australian haematologists to inform the treatments to be modelled. The base-case compares up to three courses of six cycles of R-FC ('first-line' treatment) followed by three courses of post-progression salvage ('Salvage') treatment (including rituximab) with three courses of FC followed by three courses of Salvage treatment (excluding rituximab). Subsequent treatments are incorporated into the model by repeating the unprogressed and progressed health states for each treatment. Time-dependent transition probabilities for the model were estimated from an analysis of individual patient data from CLL-8 and REACH. Comparisons of the hazard rates for the CLL-8 and REACH trials enabled an assessment of the impact on the transitions of receiving the same regimen as the first or second treatment, and hence inform assumptions regarding transitions for third and subsequent treatments. Costs applied in the model were based on published Australian prices in 2009.

RESULTS: The model predicts patients receive an average of approximately two courses of treatment, and the addition of rituximab results in an incremental gain of 0.94 quality-adjusted life-years (QALYs). The incremental cost associated with the addition of rituximab is A$40,268, and hence the cost per QALY gained (QALYG) is A$42,906.

CONCLUSION: Rituximab, in combination with chemotherapy, when used multiple times throughout the treatment algorithm, appears to be cost effective for CLL from the Australian healthcare perspective, with a cost/QALYG within the range generally accepted as providing value.