Economic evaluation
In addition to the RCT, an economic evaluation will compare costs and consequences from a societal perspective of an intervention group receiving the DSL protocol compared with a waiting list control group. Therefore, all costs and consequences of the DSL protocol will be taken into account for patient, communication partner and society. The incremental cost-effectiveness ratios (ICER) will be calculated; the difference in mean costs between intervention and control group will be divided by the difference in outcome measures between the two groups. Because costs data are generally skewed, non-parametric bootstrapping with 5000 replications of both intervention and control group will be used to derive 95% confidence intervals for the ICER. Bootstrapped cost-effectiveness pairs will be plotted in a cost-effectiveness plane and cost-effectiveness acceptability curves will be estimated [90].