Application of directed acyclic graphs in identification and control of selection bias in causal inference / 中华疾病控制杂志

In the etiology study of epidemiology, selection bias will lead to the fact that the research sample cannot represent the general population, the association between exposure and outcome among those selected for analysis differs from the association among those eligible, and the true causal association cannot be inferred. Directed acyclic graphs (DAGs) could visualize complex causality, introduce the Collider-stratification bias using simple graphics language, provide a simple and intuitive way to identify Selection bias, different types of selection bias are verified by the graphic structure of the Collider-stratification bias. In practical studies, there may be multiple biases at the same time, improper adjustment of the collider will lead to Collider-stratification bias, open a backdoor path, even change the size and direction of the confounding bias. In order to obtain an unbiased estimate of the exposure to the outcome, it is necessary to identify the collider and avoid the adjustment to prevent the occurrence of Collider-stratification bias by using DAGs.

Cognitive status and impact of tiered medical care system implementation on medical staff / 中国卫生政策研究

Objective:To understand the impact of hierarchical medical system on the medical staff at all levels of medical institutions in the pilot areas,and their cognitive status and influencing factors for hierarchical medical sys-tem,for the purpose of providing scientific reference for improving the hierarchical medical system. Methods:435 of medical staffs were selected with the help of by stratified random sampling from different levels of medical institutions from 15 pilot areas and a questionnaire survey methodology was used in this study to gather views of the medical staffs. Results:It has been revealed that after the system is implemented,there were differences in the total monthly salary,performance pay ratio,workload and the relationship between doctors and patients at different levels of medi-cal institutions. The medical staff at all levels of medical institutions had a high degree of awareness of hierarchical medical system,and the cognition rate was 81.4%. Among them,tertiary hospitals,township hospitals,community health service centers,secondary hospitals;different department categories,job titles,performance pay ratio and sal-ary changes in the medical staff have different cognition of the grading. Conclusions:To further develop the key role of medical staff in the hierarchical medical system, strengthen the attention of secondary hospitals to enhance the service capacity of primary healthcare units at the same time,reform the pay system,mobilize the enthusiasm of med-ical institutions and medical staff,and promote the development of hierarchical treatment system.

Effect of health service and its influence factors in flood disaster areas / 中南大学学报(医学版)

OBJECTIVE@#To explore the effect of health service and its influential factors in flood disaster areas.@*METHODS@#Fifty-five towns were sampled randomly from Dongting Lake area suffering from flood in 1998. The health service level, effect, and its influence factors were investigated retrospectively.@*RESULTS@#The incidence rate of notifiable infectious diseases was 11.7 per thousand, prevalence rate of chronic disease was 51.2 per thousand, infant mortality rate was 43.1 per thousand, neonatal mortality rate was 10.2 per thousand, and the total mortality rate was 554.3/100,000 in Dongting Lake area. The health investment level was significantly associated with the incidence rate of notifiable infectious diseases, the infant mortality rate, and total mortality rate. Duration of flood and income per capita were important factors for the effect of health investment.@*CONCLUSION@#Increasing health investment and residents' income in the flood disaster area, shortening the duration of flood would play positive role in residents' health in the flood disaster area.

Years of potential life of residents among different flood areas in Hunan province / 中南大学学报(医学版)

OBJECTIVE@#To determine the damage of different types of floods on the residents health.@*METHODS@#The methods of standard mortality rate (SMR) and years of potential life lost (YPLL) were used to analyze the death of sample residents from flood areas in Dongting Lake in Hunan province.@*RESULTS@#The order of death causes in the soaked area, the collapsed area and the non-flood area was the same. But the mortality rates of residents injury, poisoning and malignant neoplasm diseases in the soaked area and the collapsed area were higher than those of non-flood area. The resident standard rates of years of potential life lost (SYPLL) in the soaked area and the collapsed area were higher than that of the controls, especially in the age group of 30 to 45. The flood-attributed SYPLL in the male was higher than that of the female.@*CONCLUSION@#Flood actually affected the health of residents. The more serious the flood is, the worse the effect is. It is very important to decrease the resident mortality rate of the injury, poisoning and malignant neoplasm, and to pay attention to protect people of 30 to 45 years old in flood areas.

A research on the public health index related to the comprehensive assessment on floods / 中华流行病学杂志

<p><b>OBJECTIVE</b>To develop a public health index related to the comprehensive assessment on the impact caused by floods.</p><p><b>METHODS</b>A Analytic hierarchy process (AHP) theory was used to establish the initial evaluation system on the impact of floods. Modified-Delphi process was used to screen and determine the indicators and their weights while synthetical scored method was used to establish the comprehensive assessment model. Percentile was used to differentiate the degree of floods. Finally, analysis of variance (ANOVA) and correlation analysis were used to test the differentiability of the model for different degree of floods and the independence of these indicators.</p><p><b>RESULTS</b>The model of comprehensive assessment on the impact of floods was set up, including six first-ranking indicators and twenty-four sub-indicators. The values of comprehensive assessment were divided into five grades by the percentiles. Verified results indicated that there were significant difference among the five grades (F = 76.11, P < 0.01) and all indicators were independent.</p><p><b>CONCLUSION</b>An index of comprehensive assessment on the impact of floods was established, which could be used to evaluate the impact of floods and to differentiate the degree of flood, which seemed to have the characteristic of reliability, comprehensiveness and practicability.</p>

A study on the health status of residents affected by flood disasters / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the immediate and long-term effects of disasters caused by floods on residents health status.</p><p><b>METHODS</b>Stratified sampling by ranks of flood disaster occurred in 1996 and 1998, flood disaster areas and control areas were carried out. A retrospective study was also carried out to study all diseases involved during 1996 - 1999.</p><p><b>RESULTS</b>The incident rates of acute infectious disease in flooding areas in 1996 and 1998 were both higher than those of non-flooding areas (863.181/100 000 and 736.591/100 000, respectively). But there was no different between the incident rate of the first years in flooding areas and that of non-flooding areas. The prevalence rates of 8 kinds of chronic diseases related to circulatory system, nervous system, digestive system, injury and poisonous diseases in flooding areas were also higher than that in the non-flooding areas. The highest incidence rates of most diseases were in the mountainous flooding areas, followed by areas collapsed by flooding, and the lowest were seen in soakedareas by floods. The incidence rates of intestinal infectious diseases and respiratory infectious diseases were lower in areas where prevention and control measures were weak.</p><p><b>CONCLUSION</b>Flood could lead to the increase of incidence rates both on acute infectious diseases and non-infectious diseases. Interventions on non-infectious diseases should also be enforced to stop the epidemics when preventing and controlling acute infectious disease.</p>

Study on hospitalization expenses of flood disaster areas' residents of Dongting Lake in Hunan province in 1998 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the expenses of hospitalization among the population in the flood disaster areas of Dongting Lake in Hunan province in 1998.</p><p><b>METHODS</b>Descriptive epidemiologic study were conducted to analyze hospitalization expenses of the residents of 55 villages in flood disaster areas in 1998; single factors analysis and logarithmic linear regression analysis were carried out to explore influencing factors about hospitalization expenses of the residents.</p><p><b>RESULTS</b>The hospitalization rate was 4.59% with an average hospitalization expenses of 667.42 Yuan in the flood disaster areas' residents of Dongting Lake in 1998. Compared with populations without suffering from flood, hospitalization rate and the average hospitalization expenses of flood disaster Areas' residents of Dongting Lake in 1998 were higher and had significant difference. The average hospitalization expenses in 1998 was affected by flood types, family income, gender, age, literacy, occupation, outcome after leaving the hospital and hospital ranks.</p><p><b>CONCLUSION</b>These results implied that the flood disease aggravated inhabitants' burden of disease in Dongting Lake areas; the factors influencing the average hospitalization expenses were multiple, and synthetic measures should be taken in the prevention and control of flood disaster.</p>