Univariate deterministic sensitivity analyses were performed (modifying one variable in each analysis), together with probabilistic analyses (Monte Carlo simulation with 1,000 analyses). For the probabilistic analyses, the following variables were sampled on a random basis: utilities (beta distribution), PFS (Weibull distribution), sampled using Cholesky decomposition15 and postprogression survival (exponential distribution), all costs including adverse events (AEs), monthly cost of supportive therapy in PFS and progression, and the costs of administration of the medicines, as well as the rate of AEs (log-normal distribution). The economic model was generated using Microsoft Excel.
A panel of experts composed of two hematologists (coauthors LFC and JL) and two hospital pharmacists (coauthors AB and EG-H) validated all the premises of the model.
The initial age of the modeled CLL cohort was 71.7 years, according to the mean age of patients in the CLL11 clinical trial.7 The information on mean body weight (72.2 kg) and height (162.4 cm) was obtained from the Spanish Ministry of Health (MSSSI) databases.16 The mean body surface area was calculated based on the Mosteller formula (Table 1). Consent and ethical approval for the use of this data was deemed not necessary by the authors due to no individual patient data being used. All data used are published data.
(To view a larger version of Table 1, click here.)