Estimating the treatment effect in patients with gastric cancer in the presence of Noncompliance
Gastroenterology and Hepatology from Bed to Bench,
26 April 2021
Background: In medical sciences, to estimate of treatment effect in the presence of Noncompliance simple and advance method is used. In this paper, the treatment effect was estimated in patients with gastric cancer using these methods in the presence of Noncompliance.
Methods: In this historical cohort study, 178 patients with gastric cancer underwent chemotherapy (surgery plus chemotherapy group) and 193 patients underwent surgery, and chemotherapy (chemotherapy alone group) who entered from 2003 to 2007 to the cancer institute of Imam Khomeini Hospital (Tehran) were surveyed. Demographic and clinical characteristics were extracted from patients' hospital records. The survival of patients was calculated from diagnosis to death or the end of the study. The treatment effect was estimated using three methods: treatment as a time-dependent covariate, IPCW, and Structural Nested Models using STATA and R software.
Results: Fifty-six patients (31.5%) undergoing chemotherapy and 69 patients (35.8%) undergo surgery-chemotherapy died by the end of the study. The hazard ratio in the group I compared to group II was estimated between 1.5 to 2.07 times based on the simple analysis method. Still, the modified hazard ratio was estimated to be 1.21 (95% CI: 1.11-1.32) based on SNM method. surgery plus chemotherapy is superior to chemotherapy alone, and it improves the OS of gastric cancer patients.
Conclusion: the survival in patients undergoing chemotherapy and surgery compared to chemotherapy alone improved. The results of our study suggest that we can estimate treatment effect be unbiasely using the appropriate method.
Keywords: Treatment effect, Noncompliance, time-dependent covariate, Inverse Probability of Censoring Weights, Structural Nested Model
- Keywords: Treatment effect, Non-compliance, PP, ITT, SNM
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