2.4 Sensitivity analyses
To address the uncertainty of costs and outcomes in our model, we did several 1-way sensitivity analyses. The parameters listed in Table 1-3 were varied in specified ranges of NAC and AC. In the base case analysis, a chance of ±20% to the original values were set as the upper and lower bounds.
We also performed probabilistic sensitivity analysis (PSA) to assess the combined effect of multiple parameter uncertainty on the increment cost effectiveness ratio (ICER.) Factors varied in sensitivity analyses included OS, base-case event probabilities, costs, utility weights and treatment time frames with distributions selected based on published literature [30]. Costs and treatment time obeyed gamma distribution, with a standard error of 10% of the original value. Utilities distribution reflected a triangular distribution, and base-case utility weights were set as the most likely value with minimum and maximum values of ±0.05. Events probabilities distribution were beta distribution, with alpha and beta parameters calculated through the event’s incidence in the study of Brandt et al [10]. The PSA was performed with 10,000 Monte Carlo simulations across all distributions.