Epidemiology Relation with Public Health

“Epidemiology is the study of the patterns of diseases and factors that causes diseases in man.”

- Center for Disease Control, US Public Health Services

Thus Public health has itself defined epidemiology and epidemiology can be said as a key discipline of public health. It is also known as one of the core sciences of Public Health. It is also considered as the foundation methodology of Public Health Research.

In the mid-1980s, five major tasks of epidemiology in public health practice were identified: 

1. Public health surveillance
2. Field investigation
3. Analytic studies
4. Evaluation
5. Linkages. 

A sixth task, policy development, was recently added. In addition, Community health assessment, screening, intervention programmers, disease investigation are also the functions of epidemiology which have significant roles in Public health.

Also, according to John M. Last, 1988, Epidemiology is defined as “the study of the distribution and determinants of the health-related states or events in specified populations, and the application of this study to the control of health problems.” Relating this definition to public health:

• Epidemiology is concerned with the collective health of the people.
• Epidemiologic findings provide sufficient evidence to direct quick and effective public health control and prevention measures.
• Epidemiology uses epidemiologic information to promote and protect the public's health. Thus, epidemiology involves both science and public health practice.
• Epidemiological data directs public health decision making and aids in developing and evaluating interventions to control and prevent health.

Thus, it serves as the foundation and logic of interventions which fulfills the purpose of public health i.e. to prevent diseases, to promote health of people and to prolong their life.

Historical Evolution of Epidemiology

Disease prevention and health promotion are the main goals of public health, a multidisciplinary field that focuses on populations and communities rather than separate individuals. Epidemiology, one of the basic sciences of public health, is defined as “the study of the distribution and determinants of disease frequency in human populations and the application of this study to control health problems.” Epidemiology has played an important role in public health achievements of the last 400 years. Key historical figures and studies have included 

1. HIPPOCRATES (400 BC): “On Airs, Waters, and Places” –Hypothesized that disease might be associated with the physical environment, including seasonal variation in illness.
2. John Graunt (1662): He was first to employ quantitative methods which described population vital statistics. “Nature and Political Observations Made Upon the Bills of Mortality” –
3. James Lind discovered the cause and prevention of scurvy using an experimental study design in the 18th century;
4. William Farr(1839): He originated many modern epidemiologic methods which included a combination of numerator and denominator data;
5. John Snow (1849-1854): He demonstrated that contaminated drinking water. It was the mode of cholera transmission in the 19th century;
6. Members of the Streptomycin in Tuberculosis Trials Committee, who conducted one of the first modern controlled clinical trials in the 1940s;
7. Doll and Hill conducted case-control studies on smoking and lung cancer in the 1950s;
8. Frances et al. (1950) performed formal field trial of the Poliomyelitis vaccine in school children;
9. Dawber et al. (1955) used the cohort design to study risk factors for cardiovascular disease in the Framingham Heart Study;
10. Finally, during the 1960s and early 1970s application of epidemiological methods/interventions got succession in the eradication of smallpox worldwide in 1977.

In recent years the field of epidemiology has greatly expanded in scope, size, and influence. The 21st century poses even more challenging problems for epidemiologists like non-communicable diseases, mental health diseases, aging issues, disaster management, etc.. Like past public health achievements, the solutions to these problems are being studied with the huge contributions of epidemiology in the context of public health action.

Reference: 

Essentials of Epidemiology in Public Health by Ann Aschengrau, George R. Seage

Scale Construction

The scale construction is viewed as a specialized area of survey design. Its main purpose is designing a questionnaire, which provides a quantitative measurement of a hypothetical variable. However, not all surveys are scales, so before trying to apply the procedures to the questionnaire development, the researcher should decide whether it really is a scale.

Steps:

    1. Determine clearly what it is to be measured
    
    2. Generate an item pool 

• Make the questions simple
• Make the items as simple and straightforward as possible 
• Design the items so that they can be answered with very little instruction 
• Always avoid double-barreled questions, where the item actually combines two different questions into one 
• Avoid non-monotonic questions, where people could provide the same answer to a question for two different reasons. 
• Make the questions clear
• Questions which are unclear can cause respondents to interpret the items in different ways; an item should be designed in such a way that every respondent interprets it in the same way. 
• Avoid using any vague words or phrases in the items. 
• Level of the language used in the questions should be appropriate to the intended target audience of the scale. 
• Asking for respondents’ opinions about social groups or political structures should be taken care; these questions assume that the respondent has a single, uniform opinion about the entire entity, which may or may not be true. For example, the question “How do you feel about your parents?” would be difficult to answer for someone who has positive feelings about one parent but negative feelings about another. 
•  Avoid biased language 

      
      3. Determine the format for measurement (Nominal, Ordinal, Interval, Ratio)
      
      4. Have initial item pool reviewed by the experts
      
      5. Consider inclusion of validation of items
     
      6. Administer items to a sample
     
      7. Evaluate the items
     
      8. Optimize the scale length

Formative Research and Its Importance

Formative Research is a research conducted during the development of a program or intervention to help decide on and describe the target audience, understand the factors which influence their behavior and determine the best ways to reach them. It looks at behaviors, attitudes, and practices of target groups; it involves exploring behavioral determinants and uses a myriad of methods to collect data.

Why is formative research important?

1) Formative research informs planning and research design.

• Gaps identification in knowledge and barriers 
• Informs intervention design, practices, program, initiatives 
• Designs health programs that are effective and efficient in reaching target audiences 
• Provides the framework for developing interventions in other contexts. 

2) Formative research ensures that the program is culturally appropriate and increase the understanding of the context of the study area.

• Identifies culturally sensitive and appropriate intervention program 
• Assesses the acceptability at the family and community level 
• Modifies interventions and approaches to fit the local context 

3) Formative research helps in developing partnerships with community people.

• Promotes community engagement 
• Increases the possibility that acceptable, effective, and sustainable interventions are developed 

4) Formative research understands why certain approaches work and others do not.

• Understands what causes an intervention to be successful 

5) Formative research develops culturally appropriate and robust study instruments.

Literature Review and Its Importance in Research

A literature review in a research is a critical discussion and summary of scholarly articles, research papers, literature that is relevant to particular area or topic under study.

Literature survey or literature review is important in research with following major considerations:

1. Understand the research problem being studied
2. Reveal any gaps that exist in the literature
3. Identify areas of prior research to prevent duplication of effort and avoid incidental plagiarism
4. Demonstrate the preparedness to complete the research
5. Sharpen the research focus

• Place the relevance of the research in a larger context
• Compare and contrast with other prior research 

   6. Create a rapport with research audience and build a sense of trust in the research

   7. Depending on the area of specialization, a literature review can take several forms as follows: 

• Argumentative review 
• Integrative review 
• Historical review 
• Methodological review 
• Systematic review 
• Theoretical review 

   8. Demonstrate the credibility of the research
   9. Offer comprehensive overview and guide the direction where the research is headed
 10. Justify the proposed methodology of the research