Esophageal Squamous Cell Carcinoma Treatment

The target population of the study was patients with advanced or metastatic esophageal squamous cell carcinoma who previously failed to receive first-line chemotherapy. The patients were assigned to receive either camrelizumab or chemotherapy (docetaxel or irinotecan). A partitioned survival model was established to reflect the disease progression. The model included three states: progression-free disease (PFD), progressive disease (PD), and death. The three states are mutually exclusive. All patients were assumed to enter the model in the PFD state, and that they could maintain their designated health state or develop into another health state in each cycle (Figure 1). The relative 5-year survival rate is 8% or less for patients diagnosed with metastatic disease; thus, the time horizon of the model was set to 10 years (ASCO, 2020 ; Cancer Information Service, 2020 ). The model period was set to 1 month to facilitate model operation and parameter calculation. The main results of the model output were total cost, incremental cost-effectiveness ratio (ICER), and quality-adjusted life years (QALYs). ICER refers to the additional cost required for each additional QALY. Cost and utility were discounted at a rate of 5% (Liu, 2020 ). All costs were converted to USD, with an average RMB exchange rate of $1 to 6.8974 Yuan for the full year of 2020 (National Bureau of statistics of China, 2020 ). In addition, 1–3 times the national per capita GDP in 2020 ($10,503.52) was used as the willingness-to-pay (WTP) threshold (World Health Organization, 2011 ; Liu, 2020 ; National Bureau of statistics of China, 2020 ). The TreeAge Pro 2020 software package was used to build the model and conduct statistical analysis.