Epidemiological Study Designs

1.A surgeon in a tertiary hospital has been seeing a number of cases of carcinoma of the oral mucosa. The surgeon also observed that several of the patients gave a history of chewing the leaves of a particular plant and now approaches you to help design a research study to test the association between carcinoma of the oral mucosa which is fairly rare and chewing the leaves of this plant. Answer the following:

• a) What type of study would you carry out
• b) Describe the steps in this study design
• c) What are the advantages and disadvantages of the selected study design
• d) What is the relevant measure of association and how is it calculated Problems

2.A study to assess the risk factors of anemia among adolescent girls is to be undertaken in a PHC area..

• a) Suggest an appropriate study design.
• b) List the steps of conducting this study design
• c) What are the advantages of this study design
• d) Classify epidemiological study designs
• e) Is it possible to establish a cause effect relationship
• f) List the bias/biases involved in this study

3.It was observed that low birth weight babies are increasing among women in a difficult rural area. It was decided to conduct a study to identify the risk factors of low birth weight babies

• a) What is the ideal study design you would adopt for this study
• b) What are the steps of this study design
• c) How do you calculate the measure of risk in this study
• d) What are the advantages and disadvantages of this study Problems

4.Fifty underweight children were selected from an Anganwadi and fifty controls with ideal weight for age was selected from the corresponding anganwadi, matched for age and sex. The objective was to find out the risk factors for malnutrition.  Which is the most appropriate study design for the above mentioned question.  What are the biases in the proposed study design that can occur  What are the steps of the above study design  What are the advantages and disadvantages of the above design. Problems

5.The District health officer is concerned that there may be an increase in new-onset diabetes among young individuals aged 20-45 years after COVID-19 infection. It was decided to conduct an epidemiological investigation to study the risk of getting diabetes after Covid 19 infection.

• a) What would be an appropriate study design to test this hypothesis. Justify with reasons.
• b) Enumerate and explain the steps of the study with outcome measures of association in the study for drawing inference.
• c) Enlist any two advantages and disadvantages of this study design. Problems

6.A drug company has produced a new formulation of zinc in the form of a sweetened beverage which they claim has the ability to reduce the duration and severity of diarrhea in children below five years of age. 25 ml of the beverage has to be given to children below the age of one and 50 ml for those one to five years of age, in a once-daily dosage. They request you to assist with preparing an outline for a study which they wish to do to demonstrate the efficacy of the beverage. Answer the following:  What is an appropriate study design for this study and why  List and briefly describe the steps of the study design chosen by you.  List and briefly describe TWO ethical considerations which might need to be addressed in performing this study. Problems

7.In the primary health centre where you are the medical officer, there are more number of low birth weight babies being born. You want to find out without much delay whether maternal anemia can be the associated risk factor. Answer the following:  What type of study design can you plan  What are the steps of such a study  How do you minimize the bias of the study  How will you determine the association Problems

8.Dr. Meera is a medical officer in a primary health centre. Dengue is rampant in the region. A patient brings her a strip of capsules given to him by a local health practitioner who claims that a course of this medication will prevent thrombocytopenia. Dr. Meera decides to test the medication. Answer the following: • What type of study design she should use and why • Describe in brief the steps of the study • How will she analyze the data that she has gathered Problems

9.As a medical officer recently recruited in a primary health centre, you find that there is a cotton mill in your area and its workers utilize your health services. You want to investigate whether their health is affected by the work environment. • What type of study design will you use •What are the steps of such a study • How can you analyze the data that you have collected Problems

10.Sunaina is a recent MBBS graduate who is working as a medical officer in a primary health centre. There have been a number of cases of fever from a nearby village. The villagers suspect it is because of contaminated water in the overhead tank that supplies parts of the village. She decides to investigate. Answer the following: ● What type of study design should she use. ● What are the steps of such a study. ● How she will analyze the data, that she has gathered. Problems

11.A third year MBBS student during his clinical posting observed that many patients had leukoplakia in the oral cavity. He wanted to find the risk factors for leukoplakia. Answer the following: ● State the objectives of the study ● What is the study design used and why ● State the methods of study ● State the methods of analysis ● What sort of errors can creep in Problems

12.Sanjana is a recent MBBS graduate who is working as a medical officer in a primary health centre. There a number of patients present to her with signs of jaundice. A local traditional medical practitioner tells her about the usefulness of a special plant in the treatment of jaundice. She decides to test plant. Answer the following: ● What type of study design should she use ● What are the steps of such a study ● How she will analyze the data, that she has gathered Problems

1.A case control study was conducted to determine the Association between colon cancer and high fat diet. Discuss the various steps involved in Case Control studies based on the above example

2.Design the steps of a Cohort study to be conducted among children to find out risk factors of obesity among them

3.Define bias, explain the various types of bias with suitable examples

4.Discuss the steps in conducting a RCT to determine the efficacy of a new anti- hypertensive medication

1.Migration studies

2.Record linkage

1.Case control study and Cohort study

2.What is confounding factor

3.List the steps of conducting a cohort study

4.Randomization and Blinding Substantiate your answer with reasons

5.Experimental studies are faced with more ethical issues than case control studies List the following

1.Assertion: Randomization eliminates selection bias

• Reason: Randomization reduces potential for confounding
• a) Both A and R are true and R is the correct explanation of A
• b) Both A and R are true but R is not the correct explanation of A
• c) A is true but R is false
• d) A is false but R is true

2.Fish fat is a dietary source of

• a) Randomised control trial
• b) Cohort
• c) Case control
• d) Case-cohort

3.Matching help to prevent

• a) Confounder bias
• b) Selection bias
• c) Berke Sonian bias
• d) Recall bias

4.The advantages of an occupational cohort subgroups in a cohort study all EXCEPT

• 1) Easy access to study participants
• 2) Easy follow-up of participants
• 3) Participants are cooperative
• 4) Selecting a comparison group is difficult
• a) 1, 3, 4 are correct
• b) 1, 2, 3 are correct
• c) 1, 2, are correct
• d) 1, 2, 3, 4 are correct

5.The bias in case control is

• a) Confounder bias
• b) Berke Sonian bias
• c) Selection bias
• d) All of the above

6.To reduce selection bias in case-control studies, it is recommended that

• 1) Population based designs are used
• 2) Different eligibility criteria are applied for selecting cases and controls
• 3) Both cases and controls undergo the same diagnostic procedures
• 4) Avoid hospital based design
• a) 1 and 3 are correct
• b) 1 and 2 are correct
• c) Only 2 is correct
• d) 1, 3 and 4 are correct