รวมเล่ม_PowerPoint_ว.ระบาดวิทยาฯ 2565 (Wanpen)

Questions of descriptive study 1. What diseases do you have in the population/who has those diseases? 2. How important is the disease/problem in the population? 3. Where does the disease occur? 4. What is the trend of the disease? 5. What is the effect of the disease on the population? 6. In the case of public health services, which affects the measure/service? 7. What factors are related to the occurrence of the disease? Difference/Similarity/Correlation

Types of descriptive study Cross-sectional descriptive Prospective descriptive Retrospective descriptive study study study • Survey method • longitudinal study • Retrospective • Prevalence Rate • Incidence Rate • Examples • 1) Case report: It is a report of • Examples : • Examples • 1) Survey the prevalence • 1) Study on blood pressure 1 patient in detail about the signs, symptoms, diagnosis, and of any new disease in the levels of people aged 35 years medical treatment. specific community and over every year, twice a year • Often studying a new disease • 2) Survey the prevalence to monitor the incidence of that has never been seen of all existing asthma in hypertension in Thai people. before areas with excess PM 2.5. • 2) Study of residual 2) Case series: It is the report of abnormalities or symptoms of two or more patients with the long COVID-19 after being same disease over a period of diagnosed COVID-19 among the time. Thai people by following up for a period of 5 years. Ecologic studies assess the overall frequency of disease in a series of populations

Three types of observational/descriptive studies - Observation and describe the occurrence and distribution of disease, - No comparison group Past Present Future Retrospective Cross-sectional Prospective descriptive study descriptive study descriptive study 1) Case report: individual 3) Ecologic studies: a series of populations 2) Case series : individual

Benefits of Descriptive Study 1. To discover new diseases or health problems and create new knowledge. 2. To provide information about the health status of the population, disease prevalence, disease incidence, and public health necessity. 3. To discover risk factors that may be caused disease or health problems 4. To formulate the basic assumptions related to the risk factors or probable factors.

Epidemiology Study Type Observation intervention? no yes Intervention Comparison group? 1. Clinical trial 2. Field trial no yes 3. Community trial Descriptive Analytical Case reports or case series Cohort Ecological Case-control Cross-sectional study Cross-sectional 16

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Chapter Contents Overview of Experimental Study Design 2 Experimental Study Design Quasi-experimental design

Overview of Experimental Study Design • An experimental study, commonly known as a trial, involves the use of designed experiments to investigate the role of some agent in the prevention or treatment of a disease. Aschengrau, A. & Seage, G. R. (2020). Concept of Experimental Study Aschengrau, A. & Seage, G. R. (2020). Essentials of epidemiology in public health. 4 th.Burlington, MA: Jones & Bartlett Learning.

Experimental Study 1. The study population consisted of those who received and did not receive the factors studied. 2. Exposure occurs before the expected outcome. 3. Measure the incidence of the condition that is expected to be an outcome. 4. The researcher can directly control the research process. 5. Use a systematic sampling process based on the likelihood of probabilities. (randomization) Basic structures of experimental study Source: https://betterthesis.dk/research-methods/empirical-studies/1121-2

Characteristics of an experimental study - Prospective / Present Future Cohort study + outcome Study Manipulate follow - outcome - Outcome and Population (exposure) Exposure + outcome - None- random allocation - outcome exposure Measure - No Control follow outcomes outcome or (none-exposure) disease-free Initially the Study (Source: Jekel, Katz, Elmore, & Wild, 2007 p 81) (Onset of study)

Characteristics of an experimental study Experimental group follow Diseased (+) Disease-free + Manipulate follow Non-diseased (-) follow (exposure, +) Diseased (+) Non-diseased (-) Comparison/Control group Disease-free + Manipulate End of Study (no exposure, -) Initially the Study (Onset of study)

True experiments have four elements: ➢ manipulation ➢ control ➢ random assignment ➢ random selection The most important of these elements are manipulation and control.

Quasi-experimental Design • \"Quasi-experimental research is similar to experimental research in that there is the manipulation of an independent variable. • It differs from experimental research because ….. ✓ no control group ✓ no random selection ✓ no random assignment ✓ no active manipulation

Quasi-experimental Design ✓Quasi-experiments design can be perfect to determine what is best for the population. ✓Involves real-world problems and solutions and not any artificial ones. ✓Offers better control over the third variable known as the confounding variable which influences the cause and effect.

The disadvantages of a quasi-experimental design ➢ It serves less internal validity than true experiments. ➢ Due to no randomization, the confounding or third variable does not eradicate. ➢ It has scope for human errors. ➢ It can allow the researcher’s personal bias to get involved. ➢ Human responses are difficult to measure.

Differences between quasi-experiments and true experiments True experimental design Quasi-experimental design Assignment to treatment Assignment to treatment ✓ The researcher randomly assigns subjects ✓Some other, non-random method is used to control and treatment groups. to assign subjects to groups. Control over treatment Control over treatment ✓Does not have control over the treatment ✓ The researcher usually designs the treatment. Use of control groups Use of control groups ✓ Requires the use of control and ✓Control groups are not required (although treatment groups. they are commonly used) Source: https://www.scribbr.com/methodology/quasi-experimental-design/

Type of Epidemiology Experimental Design 1 Clinical trial (การทดลองทางคลนิ กิ ) 2 Field trial (การทดลองสนาม) 3 Community trial/Community intervention study (การทดลองในชุมชน )

Strengths: The experimental method makes it possible to determine whether changes in the independent variable cause subsequent changes in the dependent variable. Weaknesses: The main weakness of the experimental method is that subjects may behave differently in the experimental setting than they would under more ordinary conditions.

Summary - True Present Future Experimental + outcome Study Manipulate follow - outcome - Quasi- Population (exposure) Experimental - None- random allocation ✓ Assignment to exposure treatment Control follow + outcome - No (none-exposure) - outcome ✓ Control over outcome or treatment disease-free Measure outcomes ✓ Use of control Initially the Study groups (Onset of study)





1 Clinical trial (การทดลองทางคลนิ กิ ) 2 Field trial (การทดลองสนาม) 3 Community trial/Community intervention study (การทดลองในชมุ ชน )

1 Clinical Trial (การทดลองทางคลนิ กิ )

• A type of research study, a prospective design that tests how well new medical approaches work in people. • These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. • Clinical studies can take place in many locations, including hospitals, universities, doctors' offices, and community clinics. The location depends on who is conducting the study. • A clinical study is conducted according to a research plan known as the protocol.

• A Phase I trial tests an experimental treatment on a small group of often healthy people (20 to 80) to judge its safety and side effects and to find the correct drug dosage. • A Phase II trial uses more people (100 to 300) after the result in Phase I is on safety, the emphasis in Phase II is on effectiveness and continuing to study safety, including short- term side effects. • A Phase III trial gathers more information about safety and effectiveness, studying different populations and different dosages, using the drug in combination with other drugs. The subjects usually range from several hundred to about 3,000 people. (approve the experimental drug or device) • A Phase IV trial gathers more information about a device or drug's effectiveness and safety by monitoring large, diverse populations.

Specific purposes of Clinical Trials Source: https://www.risklick.ch/blogs/Objectives-of-Clincal-Trials

Field Trial (การทดลองสนาม)

Features of Field Trial (การทดลองสนาม) • One type of interventional study is designed to evaluate prevention strategies (Prospective study) • Carried out with people who are at risk, free of disease • Carried out on the field in people not admitted to a hospital or an institution • Field trials can be carried out among individuals or groups of people • The group may be a household, a block of houses, a school, or a workplace. • To test health education methods, training procedures, or other public health programs.

Sample of Field Trial Studies (การทดลองสนาม) ➢ Prevention interventions: - vaccine effectiveness studies; - nutritional interventions - interventions in maternal and neonatal health - education (campaigns against tobacco, exclusive breastfeeding, improvement of excreta disposal methods) - vector control and disease transmitters (measures to control insects, larvae, or elimination of breeding grounds)

Field Trial (การทดลองสนาม) Strengths • Helpful in assessing the value of new strategies to prevent the risk of certain diseases. • It can evaluate a single variable in a precisely defined group of people. • Eliminates bias by comparing two otherwise identical groups. • Able to control selection, confounding, and measurement biases. Source: https://thebiologynotes.com/field-trials/

Field Trial (การทดลองสนาม) Limitations of Field Trial ❑ Field trials usually require a greater number of subjects than clinical trials and therefore are usually much more expensive. ❑ A field trial often necessitates visiting subjects in the field or establishing centers from which the study can be conducted and to which subjects are urged to report. ❑ Field trials are often logistically complicated. ❑ Ethical and practical limitations. Source: https://thebiologynotes.com/field-trials/

3 Community Trial/Community Intervention Study (การทดลองในชุมชน)

Community Trial/Community Intervention Study (การทดลองในชุมชน) • Community trials, also called community intervention studies, are (mostly preventive) experimental studies with whole communities (such as cities or states) as experimental units; that is, interventions are assigned to all members in each of a number of communities.

Sample of Community Trials: fluoride in preventing dental caries • The effectiveness of fluoride in preventing dental caries was tested by comparing the frequency of caries in the children in Kingston and Newburgh. (In the 1940s) Source: https://sphweb.bumc.bu.edu/otlt/mphmodules/ep/ep713_clinicaltrials/EP713_ClinicalTrials2.html

Sample of Community Trials: The Phuket Sandbox scheme Phuket: A case study on the possibility of living with COVID-19 ➢ During Thailand's second wave last year, inbound international tourists must be vaccinated and stay on the island for 14 days before traveling to other parts of the country. ➢ Within three months, over 75% of Phuket residents were fully vaccinated ➢ Severe cases are reported very low in Phuket, allowing tourism activities to carry on despite the spread of Omicron. \"Phuket has proved to the world that living with COVID-19 is possible and safe.\" ✓ The community trials provide important information for making public health decisions and optimizing national health programs. Source: https://eng.nhso.go.th/view/1/DescriptionNews/Phuket-A-case-study-on-the-possibility-of-living-with-COVID-19/413/EN-US

Summary It is a study of ✓ It is a study with In the ✓ Eppeseda“IncTtundotciorrxiseoihcomuospeipvthemcnleaoaomreadcsooasnmngteitusuutitviyeoseauorntpi.ccedntdwnniritotuvoiuiiytiotmcscoevatyonhaooli”etmmtd.rhfpiasritoepeenepaacnrrantgarooshserwomavueheonririepwdte.fathtli,hleeinttaaxnhhgn “patients” in a general population, ✓ hospital or clinic. exposure is often a The exposure factor means of preventing ✓ is treatment, i.e. disease, such as treatment or no vaccination to provide treatment. protection. Usually, compare the “recovery rate” ✓ The condition that is in each sample expected to be an group. outcome is usually a disease of high severity or a disease that affects public health problems.

Summary ✓ Clinical, field, and community trials are experimental study, a prospective design. ✓ Field trials differ from clinical trials in that they deal with subjects who have not yet gotten the disease and therefore are not patients. ✓ Field trials in which whole communities are the unit of allocation are called community trials.





Chapter Contents 1 2

Definition •Public health surveillance means • Surveillance means the collection, analysis, and observing, collecting, and interpretation of public health data analysis as well as information, systematically and reporting and continuous continuously as well as monitoring of the spread of disseminating the knowledge gained the disease with a for the benefit of planning systematic process for the preparation of measures and the benefit of disease control. evaluation of preventive measures to control public health problems. Surveillance PUBLIC HEALTH SURVEILLANCE

Chapter Content 1 close watch kept over someone or something (as by a detective)

Type of Epidemiological Surveillance 1. Passive surveillance (การเฝา้ ระวงั เชงิ รับ) 7. Community 2. Active surveillance surveillance (การเฝา้ (การเฝ้าระวังเชิงรกุ ) ระวงั ในชมุ ชน) Type of 3. Sentinel Epidemiological Surveillance 6. Event-based (การเฝา้ ระวงั เฉพาะ surveillance Surveillance กลุ่มเฉพาะพนื้ ท่ี) (การเฝ้าระวงั เหตุการณ์) 5. Syndromic 4. Special surveillance Surveillance (การเฝา้ ระวังกลุ่ม (การเฝา้ ระวงั พเิ ศษ) อาการ)

Epidemiological Surveillance Procedures 1. 2. 3. Collection Consolidation Analysis of data 1.1 observe 1.2 cross-examine 1.3 check 1.4 report continuous monitoring

Benefits of Surveillance 1. 2. Follow up 3. Tell the size 4. Help to 5. 6. Surveillance on the and severity of plan health Guidelines data helps find Surveillance the problem, events and for disease changes in public situation of prevention information diseases and and the policy and control health, and helps to distribution of decisions control and discover health the problem regulate changes outbreaks problems that according to in infectious in a timely arise, help to population and diseases and the manner. geography. environment. tell the importance of the problem It is a guideline for evaluating the prevention and control of that disease or problem.

Chapter Content 2

Introduction of Epidemiological Investigations • An epidemic investigation is an important element in which medical personnel must be interested because it could help to solve the incidence of an outbreak. • Investigation of the outbreak help to find the source of the disease and how it is spread as well as groups of patients at high risk of disease to control the outbreak and reduction incidence quickly and help to design measures to prevent future outbreaks.

Type of Epidemiological Investigation 1. Individual case investigation 2. Outbreak investigation (การสอบสวนผู้ปว่ ยเฉพาะราย) (การสอบสวนการระบาด) These are often dangerous communicable diseases such This is to collect data in the event that there as cholera, Plague (กาฬโรค) or diseases that were are more patients than usual. previously a serious problem such as diphtheria, and rabies. or diseases that are about to be wiped out, such as The main objective is to control and prevent disease according to a collection of polio, and neonatal tetanus, measles, etc. information on various elements related to the outbreak occurring in the community. The purpose of the investigation is to confirm the diagnosis and identify the objects (or people/animals) To get a detailed description of the true that are likely to be the source of the disease, the condition of the outbreak both in terms of nature of the disease, and control methods to prevent it confirming the diagnosis and searching for from spreading as well as collecting the necessary disease sources and risk factors for additional information that is not available in the developing the disease.

Definition of Epidemic & Outbreak & Cluster ➢ Epidemic: the occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time. Usually, the cases are presumed to have a common cause or to be related to one another in some way. ➢ Outbreak: epidemic limited to a localized increase in the incidence of disease ➢ Cluster: aggregation of cases in a given area over a particular period without regard to whether the number of cases is more than expected. 1. Epidemic means an event that affects health and occurs with two or more people in a short time after participating in a common activity. For example, in the case of food poisoning at a party, the terms outbreak and epidemic are sometimes used interchangeably, but epidemic gives the impression that is a bigger situation 2. Outbreak refers: Significantly higher than the number previously collected during the same period of the previous year (mean+2 sd.), for example, the measles epidemic.