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.

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

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

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*

BACKGROUND: Idiopathic scoliosis (IS) affects patients' quality of life, yet there have been few reports of its morphology and epidemiological study in the southeast region of China. The aim of this study is to access the curve characteristics, prevalence, and factors associated with IS in Chaozhou city. METHODS: A cross-sectional study was performed in 2018, in which scoliosis screening was conducted among 5497 primary school students in Chaozhou city. Then, a case-control study based on the screening involving 2547 children was followed for the exploration of the associated factors. The questionnaires covering demographic characteristics, postural habits, cognition and self-sensation of scoliosis, and physical conditions were addressed for the investigation. ORs with 95%CIs were calculated based on logistic regression analysis to evaluate the factors associated with scoliosis. RESULTS: The prevalence of IS among primary school students was 6.15% in Chaozhou city, with 4.04% for males and 8.71% for females. The average Cobb angle was 15° (range 8 to 37°). Multiple logistic regression analysis suggested that female (OR=2.45), BMI (OR=0.67), having myopia (OR=1.49), self-sensation of scoliosis with symptoms (OR=5.52), insufficient sleep time (OR=2.65, 3.33), and less exercise time (OR=7.09, 7.29) were significantly associated with IS. CONCLUSIONS The prevalence of IS among primary school students in Chaozhou was at an average level, and it was significantly higher in females than in males. Lower body mass, having myopia, insufficient sleep time, and lower physical activity were associated with IS.
Case-Control Studies ; Child ; China/epidemiology* ; Cross-Sectional Studies ; Epidemiologic Studies ; Female ; Humans ; Male ; Myopia/complications* ; Risk Factors ; Schools ; Scoliosis/physiopathology* ; Students

BACKGROUND: Given the important repercussions that sociodemographic factors can have on physical activity, especially in the field of leisure, and cardiometabolic risk, it seems relevant to analyze the implications of these variables on the relationship between physical activity in leisure time (LTPA) and cardiometabolic risk. In this sense, the present study aims to verify the moderating role of biologic and socioeconomic factors in the relationship between LTPA and cardiometabolic risk in adolescents in southern Brazil. METHODS: Cross-sectional study that included 1596 adolescents selected at random (58.2% girls), aged between 10 and 17 years. LTPA, biological and socioeconomic factors were assessed using a self-reported questionnaire and the cardiometabolic risk score (total cholesterol/HDL-c ratio, triglycerides, fasting glucose, systolic blood pressure, and waist circumference, considering the participant's age and sex) was included as an outcome. Associations and moderations were tested by multiple linear regression models. RESULTS: It was observed a positive interaction of LTPA and sex (p = 0.048) and LTPA and school system (p = 0.037), and negative interaction of LTPA and skin color (p = 0.040), indicating that these factors were moderators in the relationship between LTPA and clustered cardiometabolic risk score (cMetS) in adolescents. A reduction in cardiometabolic risk was observed according to the increase in weekly minutes of LTPA among boys, non-white adolescents, and students from municipal schools. CONCLUSIONS The association between LTPA and cardiometabolic risk was moderated by sex, skin color, and school system in adolescents from southern Brazil.
Adolescent ; Age Factors ; Brazil/epidemiology* ; Cardiometabolic Risk Factors ; Child ; Cross-Sectional Studies ; Effect Modifier, Epidemiologic ; Exercise ; Female ; Humans ; Leisure Activities ; Male ; Sex Factors ; Skin Pigmentation ; Socioeconomic Factors

E-cigarettes (ECs) and heated tobacco products (HTPs) have become popular in Korea; hence, it is important to determine whether ECs and HTPs are less hazardous than combustible cigarettes (CCs). In general, the levels of harmful and potentially harmful constituents (HPHCs) are lower in ECs and HTPs than in CCs, although the levels of some heavy metals and HPHCs are higher in ECs and HTPs than in CCs. ECs and HTPs showed possible adverse effects on respiratory and cardiovascular system function, which could result in chronic respiratory and cardiovascular system diseases in animals. An analysis of biomarkers showed that ECs had possible adverse health effects on the respiratory and cardiovascular systems, in addition the effects of HTP on respiratory and cardiovascular systems were not significantly different than those of CC. Epidemiological studies identified positive associations between EC use and asthma, chronic obstructive pulmonary disease, and myocardial infarction. Only one epidemiologic study reported a positive association between ever using HTPs and asthma, allergic rhinitis, and atopic dermatitis among adolescents. Modelling studies of ECs did not show consistent findings regarding the health effects compared with those of CCs. A modeling study of HTPs, performed by tobacco industry, has been criticized for many unfounded assumptions. Lower levels of HPHCs in ECs and HTPs, compared with those in CCs, cannot be directly translated into health benefits because the relationship between exposure and effects is non-linear for cardiovascular diseases and because the duration of exposure is more important than the level of exposure in determining lung cancer mortality. In summary, there is no definite health benefit in using ECs or HTPs instead of CCs, for the individual or the population; hence, tobacco control measures should be the same for ECs, HTPs, and CCs. ECs and HTPs have become popular in Korea; hence, it is important to determine whether ECs and HTPs are less hazardous than CCs.
Adolescent ; Animals ; Asthma ; Biomarkers ; Cardiovascular Diseases ; Cardiovascular System ; Dermatitis, Atopic ; Electronic Cigarettes ; Epidemiologic Studies ; Hot Temperature ; Humans ; Insurance Benefits ; Korea ; Lung Neoplasms ; Metals, Heavy ; Mortality ; Myocardial Infarction ; Pulmonary Disease, Chronic Obstructive ; Rhinitis, Allergic ; Smoking ; Tobacco Industry ; Tobacco Products ; Tobacco