Dich te moi truong dai hoc
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DH Y DUOC TP.HCM KHOA YTCC BM DICH TE HOC GIANG VIEN: TS. DO VAN DUNG
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Dich te moi truong dai hoc
- 1. Dịch tễ học môi trường Đỗ Văn Dũng
- 13. Dose-Response Between Occupational Sound Levels and Percentage of Workers with Impaired Hearing for Different Age Groups … . Noise exposed factory workers ---- General population
- 22. Dose-Response curve for various health effects of lead on children
- 24. Dose-Response Between Occupational Sound Levels and Percentage of Workers with Impaired Hearing for Different Age Groups … . Noise exposed factory workers ---- General population
- 25. Dose-Response relationship between Speed and Risk of Injury for seatbelt use and non-use
- 26. Dose-Response Relationship Between Noise Level and Annoyance
- 49. Cảm ứng bệnh và tiềm tàng Thời kì cảm ứng Khoảng tiềm tàng Phơi nhiễm Thời gian cảm ứng thực tiễn
- 61. Nghiên cứu cắt ngang về tỉ lệ hiện mắc của các triệu chứng hô hấp và phơi nhiễm với khí thải giao thông OR=2,5 Khoảng cách đến đường Ran rít mãn tính Không bị ran rít mãn tính <20 m 56 514 20-150m 24 554
- 63. Thiết kế nghiên cứu đoàn hệ
- 67. Điểm chỉ số phát triển trí tuệ trung bình theo nồng độ chì máu cuống rốn
- 70. Thiết kế nghiên cứu bệnh chứng
- 76. Thiết kế nghiên cứu thực nghiệm
- 78. Thử nghiệm cộng đồng: Sâu mất trám (SMT) ở răng vĩnh viễn trên 100 trẻ tuổi 6-16 dự trên khám lâm sàng và X-quang 10 năm sau khi bắt đầu Flour hóa - New York, 1954–55 Tuổi Số trẻ ở Newburg Số trẻ Kingston SMT/100 Newberg SMT/100 Kingston Sự khác biệt 6–9 708 913 98.4 233.7 -57.9 10–12 521 640 328.1 698.6 -53 13–14 263 441 610.1 1170.3 -47.9 15–16 109 119 975.2 1648.7 -40.9
- 79. Tỉ lệ triệu chứng với 70% không khí tuần hoàn lại so với không khí hoàn toàn mới Jaakkola et al., 1994 Outcome Nhiều hơn Ít hơn Như cũ Tỉ số Nhức đầu 25 16 31 1.6 Khô mũi 22 15 35 1.5 Xung huyết mũi 20 18 34 1.1 Ban 10 9 53 1.1 Chảy mũi 14 19 40 0.7 Ngủ gà 11 12 49 0.9
- 84. Thay đổi nhịp tim và nồng độ các hạt lơ lửng ở ngày trước
- 88. Thay đổi nhịp tim và nồng độ các hạt lơ lửng ở ngày trước
Notas do Editor
- Basic Study Designs Type of study Unit of study Descriptive studies Individuals or populations Analytical studies Ecological Populations Cross-sectional Individuals Cohort Individuals Case–control Individuals Experimental studies Randomized controlled trial Patients Field trials Healthy people Community trials Communities Descriptive Studies • Description of the health status of a population (community, nation, etc.) – Person, place, and time • No formal attempt to test hypothesis or link exposure and health outcome • Generally based on existing data – Birth or death statistics – Hospital discharge data – Health surveys
- Descriptive Studies • Description of the health status of a population (community, nation, etc.) – Person, place, and time • No formal attempt to test hypothesis or link exposure and health outcome • Generally based on existing data – Birth or death statistics – Hospital discharge data – Health surveys
- Ecological Studies • Unit of analysis is group or population, rather than individuals – Schools, factories, counties, or nations • Compare aggregate measure of health outcome with aggregate measure of exposure and covariates across groups – Spatial or temporal patterns • Generally based on existing data
- Ecological Studies • Advantages – Can be done quickly and inexpensively, often using already available information – May be able to identify associations by examining greater range in exposure – May be able to evaluate ecological or contextual effects
- Ecological Studies • Disadvantages – Quality of existing data may be limited – Cannot link exposure with disease in individuals • Ecological fallacy: pattern in aggregate data does not reflect relationships at individual level • Average exposure and disease data may mask more complex associations – Difficult to control for confounding effects and bias
- Design of Cross-Sectional Study • Choose sampling frame for selecting study participants • Measure exposure and health outcome status of the study participants – Health outcomes are based on prevalence, not incidence of conditions
- Cross-sectional Study of Respiratory Symptom Prevalence and Exposure to Automobile Exhaust Distance from Chronic No chronic roadside wheeze wheeze < 20 m 56 514 20–150 m 24 554 Odds ratio = 2.5
- Limitations of Cross-Sectional Studies • Distinguishing incident versus prevalent cases • Interpreting temporal sequence • Selective survival of study subjects
- Steps in a Cohort Study • Identify and select study population • Classify study population according to exposure status and other risk factors • Follow cohort members over time to determine health outcome occurrence by exposure status sub-groups
- Examples of Cohort Studies • Populations exposed to radiation – Japanese populations who experienced WW II nuclear bomb explosions – Children who underwent radiation treatment for an enlarged thymus – Women treated with radiation for post-partum mastitis – Communities who were affected by the Chernobyl nuclear accident
- Examples of Cohort Studies • Environmental poisoning episodes – Yusho Disease - due to ingestion of rice oil contaminated with polychlorinated biphenyls – Minamata - children living near Minamata who were exposed to methyl mercury • Populations exposed to acute releases of toxic chemicals from industrial facilities – Pesticide factory in Bhopal, India, from which methyl-isocynate leakage killed more than 2000 people and poisoned 200,000 others in 1984
- Cohort Studies • Advantages – Can determine incidence rates and attributable risk directly – Exposure can be determined with less potential for bias than if outcome were already known – Can be efficient for studying rare exposures
- Cohort Studies • Advantages – Can determine incidence rates and attributable risk directly – Exposure can be determined with less potential for bias than if outcome were already known – Can be efficient for studying rare exposures
- Cohort Studies • Disadvantages – Inefficient, because must follow many more subjects than will experience the event of interest – Expensive – Results not available for long time – Bias due to attrition or loss to follow-up
- Steps in a Case–Control Study • Establish a case definition • Identify sampling frame for selecting cases and controls • Assess prior exposure status and other risk factors for cases and controls • Compare prior exposure experiences of cases and controls in order to estimate association between exposures and health outcome
- Examples of Case-Control Studies • Lung cancer and residential exposure to radon • Lung cancer and indoor air pollution in China • Leukemia in individuals exposed to radioactive fallout from nuclear testing facilities in the USA
- Case-Control Studies • Advantages – Relatively efficient and inexpensive. Especially efficient for rare diseases – Useful for studying diseases with long latencies – Can assess the potential effects of several exposures on disease
- Disadvantages – Difficulty selecting appropriate comparison group – Potential bias in measuring exposure: • Outcome may affect subject's recollection of the exposure • Outcome may affect the measurement or recording of the exposure – Cannot directly estimate attributable risk
- Experimental Studies • “ Natural Experiments” – Monitor changes in health outcomes associated with change in environmental condition or regulation • Controlled human exposure studies – Respiratory and neurobehavioral effects of exposure to air pollutants or solvents – Reproductive hormone and immune mediators changes • Community trials
- Community Trial : Permanent Teeth Decayed, Missing, or Filled (DMF) per 100 Children, Ages 6–16, Based on Clinical and Roentgenographic Examination Ten Years After Start of Fluoridation — New York, 1954–55 6–9 708 913 98.4 233.7 -57.9 10–12 521 640 328.1 698.6 -53 13–14 263 441 610.1 1170.3 -47.9 15–16 109 119 975.2 1648.7 -40.9
- Outcome Nhiều hơn Ít hơn Như cũ Tỉ số Nhức đầu 25 16 31 1.6 Khô mũi 22 15 35 1.5 Xung huyết mũi 20 18 34 1.1 Ban 10 9 53 1.1 Chảy mũi 14 19 40 0.7 Ngủ gà 11 12 49 0.9
- Experimental Studies Strengths Most definitive study design because investigators “assign” exposure Possible to evaluate effects of dose Able to study temporal relationships Weaknesses Limited to study of short-term, reversible effects of potentially harmful agents, or of treatment or preventive interventions. Generalizability when studying volunteers Potential high cost and lost to follow-up
- Common Study Designs for Environmental Epidemiology • Community-based cross-sectional and case-control studies – Cancer studies using registry • Ecological studies – Spatial and temporal patterns • Increasing use of spatial mapping (GIS) • Time series studies – Ecological time-series – Panel studies
- Time-series Studies • Correlation between changes in exposure over time with changes in outcome over time • Strengths – Communities or persons serve as their own controls (reduces confounding) • Weaknesses – Can study only reversible effects in individuals – Requires sophisticated statistical analysis • Time-series modeling (GEE, GAM) • Case-crossover analysis
- Examples of Time-Series Studies • Ecological Studies – Variation in mortality, hospitalizations, and emergency room visits with changes in air pollution using aggregate data in major cities • Panel Studies – Variation in asthma symptoms, medication use, and peak flow with changes in exposure to air pollutants and fungal spores, measured via air and personal monitoring – Heart rate variability and exposure to ultrafine particles
- Common Study Designs for Environmental Epidemiology • Community-based cross-sectional and case-control studies – Cancer studies using registry • Ecological studies – Spatial and temporal patterns • Increasing use of spatial mapping (GIS) • Time series studies – Ecological time-series – Panel studies
- Time-series Studies • Correlation between changes in exposure over time with changes in outcome over time • Strengths – Communities or persons serve as their own controls (reduces confounding) • Weaknesses – Can study only reversible effects in individuals – Requires sophisticated statistical analysis • Time-series modeling (GEE, GAM) • Case-crossover analysis
- Examples of Time-Series Studies • Ecological Studies – Variation in mortality, hospitalizations, and emergency room visits with changes in air pollution using aggregate data in major cities • Panel Studies – Variation in asthma symptoms, medication use, and peak flow with changes in exposure to air pollutants and fungal spores, measured via air and personal monitoring – Heart rate variability and exposure to ultrafine particles
- - In summary, case crossover design is used when a brief exposure causes a transient change in risk of an acute onset event. The event can be the onset of type I diabetes, a motor vehicle accident, or an injury. The “exposure” can be another disease or certain activity, such as having an infectious disease, conducting a certain unusual task, or using a certain device. There is a hazard period associated with the event onset and the exposure information in the hazard period is compared with the control data from a selected control period. - In the next few slides I will formally introduce hazard period, effect period and control data.