Strengths and limitations
PD
DISEASE
A major strength of the basic analysis was its dependence on a direct comparison of pembrolizumab and standard chemotherapy, utilizing data and information from a randomized controlled trial. In addition, the PSM structure is unnecessary for building assumptions for the transition probabilities of patients but has the advantage of being able to partition patients to different health states directly based on the trial’s K-M curves. Moreover, the time dependence of risk can be handled automatically instead of applying constant transition risks within a traditional Markov model.It is essential to note that our study had several limitations. First, the development of the cost-effectiveness analysis was based on the results of the KEYNOTE-177 trial, in which the participants were mainly from the Western Europe or North America (> 70%). To some extent, this may impair the application of our research results. Second, the values of utilities of PFS and PD were derived from the study on the health-related quality of life in the trial population (the sample size might not be sufficient to reflect the true utilities), and the disutilities of AEs were derived from previously published studies, which might not reflect the health state of patients in China. This defect may also affect the robustness of our results. Updated health utility data for patients with dMMR/MSI-H metastatic or unresectable CRC in Chinese populations might enhance the accuracy and robustness of the analyses. Third, the efficacy data of PFS and the incidence of AEs were from the interim results of the trial because the final results have not been officially published. Thus, it is possible that projections of cost-effectiveness could change with additional follow-up. Fourth, without considering patient compliance, the cost of follow-up may be overestimated. Because of this, the cost of follow-up as a variable was included in the DSA, and we found that the impact of the follow-up cost on the results was small. In addition, for the longer-term extrapolation of PFS and OS, there existed an inherent uncertainty, and the perspective of the Chinese health-care system may limit the scope of application of the results. Finally, due to the research perspective, our study only included direct medical costs. If indirect costs were added, the advantage of Group P might be more significant as disease improvement could reduce indirect costs.