Bias ; Confounding Factors (Epidemiology) ; Epidemiologic Methods ; Humans

BACKGROUND: Several contradictory studies exist on the relationship between raising grandchildren and the grandparent's health. The present study identified the association between raising grandchildren and depression among Korean grandparents.METHODS: The wave 1 (2006) and wave 2 (2008) databases of the Korean longitudinal study on aging (KLoSA) were analyzed. T-test and chi-square test were used to compare the demographics and health condition variable between the two groups based on the presence or absence of raising grandchildren. Logistic regression analysis, including demographics and health conditions, was conducted to identify the relationship between depression and raising grandchildren. Depression was assessed using the Center for Epidemiologic Studies Depression scale (CES-D-10).RESULTS: In all, 4,784 participants (4,636: not raising grandchildren; 148: raising grandchildren) were examined. Significantly lower CES-D-10 scores (3.34 vs. 4.35, P<0.001), and therefore, lower depression (25% vs. 39.9%, P<0.001) was found among grandparents raising grandchildren than those who did not raise grandchildren. After adjusting the confounding variables through logistic regression analysis, the odds ratio of depression when raising grandchildren was 0.57 (95% confidence interval=0.37–0.89), which indicates significant relevance.CONCLUSION: The results show lower depressive symptoms among grandparents raising grandchildren. Even after adjusting the variables, the results presented a lower risk of depression among them.
Adult ; Aging ; Confounding Factors (Epidemiology) ; Demography ; Depression ; Epidemiologic Studies ; Grandparents ; Humans ; Logistic Models ; Longitudinal Studies ; Odds Ratio

Head computed tomography (CT) is instrumental for managing patients of all ages. However, its low dose radiation may pose a low but non-zero risk of tumor induction in pediatric patients. Here, we present a systematic literature review on the estimated incidence of brain tumor induction from head CT exams performed on children and adolescents. MEDLINE was searched using an electronic protocol and bibliographic searches to identify articles related to CT, cancer, and epidemiology or risk assessment. Sixteen studies that predicted or measured head CT-related neoplasm incidence or mortality were identified and reviewed. Epidemiological studies consistently cited increased tumor incidence in pediatric patients (ages 0–18) exposed to head CTs. Excess relative risk of new brain tumor averaged 1.29 (95% confidence interval, 0.66–1.93) for pediatric patients exposed to one or more head CTs. Tumor incidence increased with number of pediatric head CTs in a dose-dependent manner, with measurable excess incidence even after a single scan. Converging evidence from epidemiological studies supported a small excess risk of brain tumor incidence after even a single CT exam in pediatric patients. However, refined epidemiological methods are needed to control for confounding variables that may contribute to reverse causation, such as patients with pre-existing cancer or cancer susceptibility. CT remains an invaluable technology that should be utilized so long as there is clinical indication for the study and the radiation dose is as small as reasonably achievable.
Adolescent ; Brain Neoplasms* ; Brain* ; Child ; Confounding Factors (Epidemiology) ; Epidemiologic Methods ; Epidemiologic Studies ; Epidemiology ; Head* ; Humans ; Incidence ; Mortality ; Patient Safety ; Pediatrics ; Radiometry ; Risk Assessment ; Tomography, X-Ray Computed

OBJECTIVETo establish a new method on stratification analysis when the stratification limits of confounding factors was not clear or contradictory.

METHODData on a study of diabetes mellitus in Guangdong province collected in the year of 1997 and 1998 was analyzed using cluster-stratification analysis.

RESULTSThe efficiency of stratification analysis was improved and the confounding bias was effectively controlled with information bias avoided when the clusters-stratification analysis was applied.

CONCLUSIONThe problem was logically solved using cluster analysis as an assistant stratification means.

Adult ; Age Factors ; Aged ; Bias ; China ; epidemiology ; Cluster Analysis ; Confounding Factors (Epidemiology) ; Data Interpretation, Statistical ; Diabetes Mellitus ; epidemiology ; Epidemiologic Methods ; Humans ; Middle Aged ; Multivariate Analysis ; Reproducibility of Results ; Risk Factors

BACKGROUND: Recently in Europe, some epidemiologic studies reported that various physical symptoms and social, psychological wellbeing are related to low blood pressure. But in Korea, none has been studied on symptoms related to low blood pressure yet. In this study, we would like to see if the somatic symptoms and social, psychological wellbeing shown t,o be related to low SBP is truly associated with it. METHODS: Questionnaire interview was done to the people who have visited Department of family practice in two university hospitals and two health promotion center from April, 1996 to August, 1996. Seven somatic symptoms and Psychosocial Wellbeing Index(PWI) for the evaluation of social, psychological health status were included in the questionnaire. SAS statistics packages was used in statistical precess. We used logistic regression to see the frequency of somatic symptoms related to the systolic blood pressure(SBP) group and the confirmation of confounding variables was done by ANOVA. RESULTS: Total of 304 completed the questionnaire. Average age was 44 years old and average SBP was 115.4+/-16.4. 84 of them (27.6%) felt that they had a low BP & 69 were women compared to 21 men, being meaningfully more common. 107(35.2%) people answered that they had heard that their blood pressure was low and 66% were from doctors. Only 32(38.1%) of the group who felt of having hypotensive symptoms and 38 of the group who heard of having hypotension actually had SBP of below 100 mmHg. Vocation, income, smoking & alcohol history, present illness, marital status were not significant as a confounding variable. SBP of 100 or below group had a less presentation of fatigue & significantly higher PWI than the group of above 100mmHg (p<0.05). The group who felt that they had a low BP had more complaints of fatigue, dizziness, palpitation, cold hands and feet and had significnatly higher PWI than the group who didnt. CONCLUSIONS: SBP of 100mmHg or below group has more frequent manifestion of fatigue and low level of sociopsycholgiacl health index than the above 100mmHg group. But most of the people who complained of hypotensive symptoms didnt have low blood pressure and a lot of them misunderstand of having low blood pressure and after checking blood pressure by doctors, so great deal of caution is called for when seeing patients.
Adult ; Blood Pressure* ; Confounding Factors (Epidemiology) ; Dizziness ; Epidemiologic Studies ; Europe ; Family Practice ; Fatigue ; Female ; Foot ; Hand ; Health Promotion ; Hospitals, University ; Humans ; Hypotension ; Korea ; Logistic Models ; Male ; Marital Status ; Occupations ; Smoke ; Smoking ; Surveys and Questionnaires

BACKGROUND: Colon cancer is one of the main causes of mortality. Early adenomatous colon polyp is a precursor of colon cancer through the ‘adenomacarcinoma sequence.’ Epidemiological studies suggest that the neutrophil to lymphocyte ratio can be one of useful inflammatory markers in clinical settings. This study aimed to evaluate the association between neutrophil to lymphocyte ratio and development of early adenomatous colon polyps.METHODS: This cross-sectional study retrospectively examined 960 middle-aged and elderly individuals aged ≥45 years who underwent colonoscopy in a health examination program. Multivariate logistic regression was used to analyze the association between neutrophil to lymphocyte ratio and development of early adenomatous colon polyps.RESULTS: Among the 960 subjects, the prevalence of early adenomatous polyps was 20.7% (n=199). The mean age, body mass index, number of current smokers, white blood cell count, triglyceride level, and number of subjects receiving hypolipidemic drugs were higher in the group with early adenomatous polyps than in the multivariate analysis, the odds ratio (95% confidence interval) for the development of early adenomatous polyps was 1.23 (1.01–1.50) with neutrophil to lymphocyte ratio increment after adjusting the confounding variables (P=0.037).CONCLUSION: We found that the neutrophil to lymphocyte ratio was associated with the development of early adenomatous colon polyps among middle-aged and elderly individuals. Accordingly, this result suggests that regular monitoring of early adenomatous colon polyps may be useful among individuals with a higher neutrophil to lymphocyte ratio.
Adenomatous Polyps ; Aged ; Body Mass Index ; Colon ; Colonic Neoplasms ; Colonic Polyps ; Colonoscopy ; Confounding Factors (Epidemiology) ; Cross-Sectional Studies ; Epidemiologic Studies ; Humans ; Hypolipidemic Agents ; Korea ; Leukocyte Count ; Logistic Models ; Lymphocytes ; Middle Aged ; Mortality ; Multivariate Analysis ; Neutrophils ; Odds Ratio ; Polyps ; Prevalence ; Retrospective Studies ; Triglycerides

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

The overall details of causality frames in the objective world remain obscure, which poses difficulty for causality research. Based on the temporality of cause and effect, the objective world is divided into three time zones and two time points, in which the causal relationships of the variables are parsed by using Directed Acyclic Graphs (DAGs). Causal DAGs of the world (or causal web) is composed of two parts. One is basic or core to the whole DAGs, formed by the combination of any one variable originating from each time unit mentioned above. Cause effect is affected by the confounding only. The other is an internal DAGs within each time unit representing a parent-child or ancestor-descendant relationship, which exhibits a structure similar to the confounding. This paper summarizes the construction of causality frames for objective world research (causal DAGs), and clarify a structural basis for the control of the confounding in effect estimate.
Causality ; Computer Graphics ; Confounding Factors, Epidemiologic ; Data Interpretation, Statistical ; Epidemiologic Methods ; Humans

One of the commonly accepted merits of cohort studies (CSs) refers to the exposure precedes outcome superior to other observational designs. We use Directed Acyclic Graphs to construct a causal graph among research populations under CSs. We notice that the substitution of research population in place of a susceptible one can be used for effect estimation. Its correctness depends on the outcome-free status of the substituted population and the performance of both screening and diagnosis regarding the outcomes under study at baseline. The temporal precedence of exposure over outcome occurs theoretically, despite the opposite happens in realities. Correct effect estimate is affected by both the suitability of population substitution and the validities of outcome identification and exclusion.
Causality ; Cohort Studies ; Confounding Factors, Epidemiologic ; Epidemiologic Methods ; Mass Screening ; Research Design