Progress on development and application of the diet-related inflammatory index in cancer epidemiological studies / 中华流行病学杂志

Cancer is a major public health problem worldwide, causing an more serious burden of disease. Inflammation is considered a predisposing factor for cancer with close relationship with its incidence. In recent years, the public and epidemiologists has paid more attention to the association between nutrition and cancer and other chronic diseases in the perspective of inflammation. This paper summarizes the development and application of the diet-related inflammatory index in cancer epidemiological studies based on the literature retrieval of common diet-related inflammatory index. Firstly, we highlight the common diet-related inflammatory indices and their construction methods, such as the Dietary Inflammatory Index, a literature-derived diet-related inflammatory index, and the Empirical Dietary Inflammatory Index, an empirically derived diet-related inflammatory index, and so on. Secondly, the epidemiological research progress on the commonly used diet-related inflammatory indices is briefly introduced. Finally, the advantages and disadvantages of the two types of this inflammatory indices are also briefly described for the purpose of providing reference for nutrition epidemiological studies of cancer and other chronic diseases in China.

Statistical methods for relative risk estimation and applications in case-cohort study / 中华流行病学杂志

Objective: To systematically introduce the design of case-cohort study and the statistical methods of relative risk estimation and their application in the design. Methods: First, we introduced the basic principles of case-cohort study design. Secondly, Prentice's method, Self-Prentice method and Barlow method were described in the weighted Cox proportional hazard regression models in detail, finally, the data from the Shanghai Women's Health Study were used as an example to analyze the association between obesity and liver cancer incidence in the full cohort and case-cohort sample, and the results of parameters from each method were compared. Results: Significant association was observed between obesity and risk for liver cancer incidence in women in both the full cohort and the case-cohort sample. In the Cox proportional hazard regression model, the partial regression coefficients of the full cohort and the case-cohort sample fluctuated with the adjustment of confounding factors, but the hazard ratio estimates of them were close. There was a difference in the standard error of the partial regression coefficient between the full cohort and the case-cohort sample. The standard error of the partial regression coefficient of the case-cohort sample was larger than that of the full cohort, resulting in a wider 95% confidence interval of the relative risk. In the weighted Cox proportional hazard regression model, the standard error of the partial regression coefficient of Prentice's method was closer to the parameter estimates from full cohort than Self-Prentice method and Barlow method, and the 95% confidence interval of hazard ratio was closer to that of the full cohort. Conclusions: Case-cohort design could yield parameter results closer to the full cohort by collecting and analyzing data from sub-cohort members and patients with the disease, and reduce sample size and improve research efficiency. The results suggested that Prentice's method would be preferred in case-cohort design.