Environmental Exposure/adverse effects* ; Risk Assessment ; Epidemiologic Studies

Cohort studies is an epidemiologic study that follows a group of individuals who share a common characteristic at the start of the study to observe the emergence of outcomes. Cohort studies are classified based on the population characteristics from where they were drawn, the way the data collection occurred or if its open or closed. This allows the computation of the absolute risk or the incidence of an outcome. There are several advantages in conducting a cohort study, such as clarity of temporal relationship of the exposure and outcome, permits the computation of incidence, permits multiple effects of a single exposure, and avoids selection bias on admission. While there are advantages, there are also disadvantages in doing this study, such as it requires long follow-up, need of large sample size, maybe costly, and may make it difficult to argue causation due to the presence of confounding. The statistical test that can be used to analyze the results will depend on the type of variable used. Statistical test such as T-test, Chi square test, and Regression can be used. Writing the final report follows the STROBE guidelines.

Measurement bias (MB) has been described in causal structures but is still not entirely clear. In practice, the correctness of substitution estimate (SE) of effect is a prerequisite for causal inference, usually based on a bidirectionally non-differential misclassification between the measured exposure and the measured outcome. Based on a directed acyclic graph (DAG), this paper proposes a structure for the single-variable measure, where its MB is derived from the choice of an imperfect, "input/output device-like" measurement system. The MB of the SE is influenced both by the measurement system itself and by factors outside the measurement system: while the independence or dependence mechanism of the measurement system still ensures that the MB of the SE is bidirectionally non-differential; however, the misclassification can be bidirectionally non-differential, unidirectionally differential, or bidirectionally differential resulted from the factors outside the measurement system. In addition, reverse causality should be defined at the level of measurement, where measured exposures can influence measured outcomes and vice versa. Combined with temporal relationships, DAGs help elucidate MB's structures, mechanisms, and directionality.
Humans ; Confounding Factors, Epidemiologic ; Data Interpretation, Statistical ; Bias ; Causality

Controlling unmeasured confounders in non-randomized controlled studies is challenging. Negative control theory is based on the theoretical concept that the test result of negative controls must be negative. Setting appropriate negative control incorporates the specificity of association into population studies for the identification and control of unmeasured confounders. This paper explains the principles to control unmeasured confounders using negative control theory from a statistical perspective. A detailed introduction of derived methods based on negative control theory is also introduced, including adjusted standardized mortality ratio method, calibrating P-value method, generalized difference-in-difference model and double negative control method. The reasonable application of those derived methods is also comprehensively summarized based on representative case studies. Negative control is an important statistical design to identify, revise and control unmeasured confounders and a valuable method for comparative effectiveness research based on real-world data.
Humans ; Confounding Factors, Epidemiologic ; Research Design ; Comparative Effectiveness Research ; Bias

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.
Humans ; Diet ; Inflammation ; Neoplasms/epidemiology* ; Epidemiologic Studies ; Chronic Disease

With the increasing demand to study the cause of complex diseases, mega cohort has gradually replaced the traditional small sample cohort and become the hotspot of epidemiological research. Follow-up is the essential step in a cohort study to obtain the information about the onset and death of diseases, migration or loss of follow-up of the cases. Its quality has a direct impact on the conclusions of cohort study. Therefore, it is necessary to develop a reasonable follow-up monitoring program for a mega cohort.In this paper, we summarized the contents and methods of the follow-up monitoring program in the mega cohorts at home and abroad, which aimed to provide suggestions for the new cohort and improve the follow-up program for the existing cohort.
Cohort Studies ; Epidemiologic Studies ; Follow-Up Studies ; Humans

The rapid development of sequencing technology brings the explosive growth of pathogen genetic data. The combination of genomic data and phylogenetic method is being used to elaborate the origin and evolution of pathogens, the time and space distribution and parameter changes in the prevalence process, and how phenotypes like antigen, virulence, and resistance change over time. This method is also being used to predict pathogen transmission trends. In this study, we described the aim of phylogeny and the process of the phylogenetic construction method. We elaborated the advantages and disadvantages and scope of application of tree-building methods including distance-based, maximum parsimony, maximum likelihood and bayesian methods. We have reviewed the application and the estimation methods of major epidemiological parameters of phylodynamics and phylogeography in domestic and foreign studies. We concluded that the time- and location-scaled phylogenetic trees are increasingly used for outbreak investigation and routine surveillance of infectious diseases.
Bayes Theorem ; Communicable Diseases/genetics* ; Epidemiologic Studies ; Genomics ; Humans ; Phylogeny

Health impact assessment (HIA) system has been listed in the Outline of the Healthy China 2030 Plan and the Law of Basic Health Care and Health Promotion of the People's Republic of China, however, the technique guideline of HIA needs to be established and improved. This paper summarizes the applications of different epidemiological methods in HIA and focus on the introduction of the application of ecology model of health social determinants as theory basis in the establishment of HIA system along with the introduction of HIA cases in the world. The applications of epidemiological methods in domestic HIA research are limited. Therefore, appropriate applications of epidemiological methods should be strengthened in HIA guideline and system development, especially the applications of big health data, mobile health techniques, systems epidemiology and implementation science, to facilitate data collection and potential health hazard evaluation and surveillance for HIA, establishment and improvement of HIA system and the implementation of Healthy China Strategy.
China/epidemiology* ; Epidemiologic Methods ; Health Impact Assessment ; Health Promotion ; Humans

SARS-CoV-2 has infected more than 600 million people worldwide and caused more than 6 million deaths. The emerging novel variants have made the epidemic rebound in many places. Meteorological factors can affect the epidemic spread by changing virus activity, transmission dynamic parameters and host susceptibility. This paper systematically analyzed the currently available laboratory and epidemiological studies on the association between the meteorological factors and COVID-19 incidence, in order to provide scientific evidence for future epidemic control and prevention, as well as developing early warning system.
Humans ; SARS-CoV-2 ; COVID-19 ; Meteorological Concepts ; Laboratories ; Epidemiologic Studies

Isotemporal substitution model is a powerful tool to explore the real association between physical behavior and health outcomes, which has the potential of the application in large-scale cohort study. This paper systematically introduces the principle of isotemporal substitution model and its implementation method in specific analysis to provide analytical ideas for the epidemiological research related to physical behavior in China. The baseline data of Regional Ethic Cohort Study in Northwest China conducted in Shaanxi province were used to analyze the relationship between physical behavior and cardiovascular disease with single-factor model, partition model and isotemporal substitution model. The advantages and disadvantages of different models were compared, and the advantages of isotemporal substitution model in quantifying physical activity health risk were introduced. Isotemporal substitution model could qualify physical behavior and health outcomes, which has wide application value in epidemiological research.
Humans ; Cohort Studies ; Epidemiologic Studies ; Cardiovascular Diseases ; China/epidemiology*