Epidemiological Methods

Question 1:

Read the article “Early Life Course Risk Factors for Childhood Obesity: The IDEFICS Case-Control Study”. Available at: http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0086914

Now, answer the question below:

  • How would you select cases and controls for this study and how would you define exposure and outcome variables for a case-control study design? What other factors would you control for?


Read the article “Race and nativity are major determinants of tuberculosis in the U.S.: evidence of health disparities in tuberculosis incidence in Michigan, 2004–2012. Available at: https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-017-4461-y

Now, write a 2-page peer review of the selected journal article and make sure to include the following components:

  • Analyze the study design used by the author in your chosen article.
  • Discuss the strengths and limitations of the study design chosen.
  • Propose potential alternative study design that could have been used.
  • Discuss the article’s public health implications.
  • All articles referenced should be properly cited.

Question 3:

Sharing health data for epidemiological purposes is a highly debated issue in public health. With the increasing development of large, complex data sets, known as “big data”, the opportunities for public health also grow. With any size system come the issues of confidentiality and privacy. In public health, data are shared on a need to know basis and under strict policies.

Read the article “Big Data and Public Health: Navigating Privacy Laws to Maximize Potential:. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315864/.

Now, pick a disease/health issue. Consider your role as an epidemiologist, what are the implications for receiving data for this disease/health use to conduct epidemiological methods? What regulations will allow/not allow you to receive the data? What do you need to consider in requesting and collecting the data?

Question 4:

While the concepts of screening and surveillance are intertwined there are subtle distinctions between the two ideas.  The main goals are data collection to measure magnitude, changes, and trends in populations.  The objective is to create interventions in defined populations.  On the contrary, testing to identify individuals with infection or disease is the main goal of screening.  The area of breast cancer screening and breast cancer surveillance has been a point of contention.

Please read the following articleand weigh in on which side seems most convincing:

“Putting the “Great Mammography Debate” to Rest”. Available at: http://www.gotoper.com/publications/ajho/2015/2015sep/putting-the-great-mammography-debate-to-rest

Now, answer the question below:

  • Do you believe that US Preventive Services Task Force (USPSTF) recommendations should be followed or do you believe screening should start at age 40?  Why or why not?
  • What type of surveillance would be appropriate/necessary for this type of situation; active, passive, or sentinel? 


Q1.Selection of cases and controls for this study

To study the child obesity, the sample for this study is based on the population of childhood in the 8 selected European countries (Italy, Estonia Cyprus, Germany, Belgium, Hungary, and Sweden) and the study is set up in the pre-school and primary school context. The study sample is centered on 16,220 children of age 2 to 9 years. The selected cases are categorized into pre-partum, peri-partum and post-partum factors. The information is then gathered by administering IDEFICS parental questionnaire. The prepartum factors investigated are breast feeding, Caesarian section, BMI, gestational weight gain and smoking during pregnancy. Family-related risk factors such as social background and familial clustering are also considered in the study. Factors such as Caesarian section delivery and weight at birth are grouped under peri-partum factors.

Definition of exposure and outcome variables for a case-control study design

The case-control study indicates that there is a large disparity in a child becoming obese with respect to home country, with Italy carrying the highest risk and Sweden recording the lowest risk of child obesity. The highest risk factor however is recorded from maternal smoking during pregnancy, which stands at 50%. However, this risk factor highly exposes only exposes boys to obesity and not girls. Closer to that is contributed by gestational weight gain, which records 32% of risk. This is contributed by a mother gaining 25kg or even more during pregnancy. The case control study also indicates the higher obesity risk from caesarian birth at 95%. In contrast, breastfeeding is reported to be statistically insignificant in exposing child to obesity but statistically significant in protecting children. Weight at birth was also statistically significant in exposing a child to obesity.

Other factors that the study would control for

Apart from the variables observed above, the study would also consider factors such as; psychological factors, feeding habit and physiological factors such as exercise.

Q2. Description of the study design

The study uses random stratified data collection method with the population size of1800 TB cases from the health department of Michigan. A probability sample size of 1254 cases are then drawn from this population for the study. The variables considered for the study are race, age, gender and nativity. The sample comprised of male and female patients diagnosed with TB, and further grouped as white and foreign-born. The sample is comprised of 42% Black, 33% White and 25% Asians. The study considered the age of 18 to 104 years with a mean of 49%. From the sample taken, 40% are male while males made up the remaining 60% of the cases. The sample size was further categorized into those with pulmonary TB, which forms 70%, extra-pulmonary TB at 22% and 8% of those with both cases.

The study also uses quantitative analysis to regress the variables observed to construct a research model. Microsoft Excel (2011) is then used to plot the model.

Strengths and limitations of the study design


The study is based on facts that are collected from the Health Department of Michigan therefore giving much relevant results. The biasness of the study is limited as it considers both gender composition of the population. The study also employs advanced methods of data analysis such as the use of Microsoft Excel software. This produces a much understandable information about the population observed. The software applied here is able to produce the expected trend of TB infection. The study has used both clustered and non-clustered variables for comparison. This provides detailed information thereby adding more strength to the results.


The case study only relied on a certain group of age, that is, above 18 years. However, TB cases might been reported even in children. The data used was limited to only race, gender and nativity. In actual sense, some key variables such as exposure to other diseases were not considered. Another weakness of the study is that the sample collected only represented a 70% of the total TB reported cases. However, the study did not take in to account of the non-reported cases too. It is in the weakness of this study that it limits the study area to only one place, Michigan. It should have considered a wide region of study taking into consideration of the race and nativity such as the Blacks and the Asians.

A potential alternative study design that could have been used

In this case they would use questionnaires that would be administered to a larger population to capture additional unreported cases of TB. The study could also use a mix of both quantitative and qualitative analysis to bring out more information about TB. The sample should have taken children too into consideration. In the analysis of the results, the study would also employ other more advanced methods that would regress whole variables.

The article’s public health implications

The article has highlighted some factors that work to increase chances of TB infections. Considering this, article contributes positively to the health departments by providing some useful information that would be used to bridge. The article has also shown some trends that is featuring with the battle against TB, with U.S recording a significant decline in such cases. However, the article gives unsatisfactory information with regards to the relationship that exists between TB and race.

Q3. The implications for receiving data for Obesity/health use to conduct epidemiological methods?

Obesity is one of the diseases that have recorded a fall in the United States. This has been possible due to epidemiological methods that heavily rely on the health information privacy and the legal framework for big data. For example, epidemiological methods may depend on data from central registry for scanning to identify the gaps that exist in the healthcare.

Personal information from an obese has been used to improve the quality of health services and activities such as preventing or controlling an outbreak of a disease, disability and or injury.

Regulations that will allow/not allow one to receive the data

The common rule is one of the regulations that protects human that are involved in federally funded research as it does not govern those studies that rely on pre-existing patient information.

HIPAA’s is one of the federal laws that allows regulated entities to access and even disclose personal health information (PHI) even when carrying out activities that are outside controlling or preventing an injury, disease or disability. However, state laws and regulations strictly does not allow entities to disclose sensitive information such as mental health information and immunodeficiency syndrome test results. This is also applicable for the obesity.  The genetic information non-disclosure Act of 2008 (GINA) is another law that prohibits health programs from making decisions by using an individual generic information. This law further restricts employers against discriminating employees based on their genetic information during employment exercise.

What is needed to consider in requesting and collecting the data

When collecting data for obesity, one clearly needs to understand the legal framework for information privacy and the sensitivity of the data being collected.

Question 4.

  1. I do believe that the US preventive service task force recommendation should be followed. From the recommendation the means of development of the ways of reducing the risk of false positive recall in the different diagnosis cases are made possible. The annual screening specific age recommendation developed by the task force meets the minimal requirement that is offered by the experts on the breast cancer situations. In addition, the recommendations be the USPSTF) offers a considerably stronger methods of better procedure in the breast cancer treatment that prevents the cases of over diagnosis and overtreatment which has become one of the common emerging problems associated with the treatment of breast cancer at different stages. The recommendation equally is well informed. The impetration of the proponent in the screening mammography as a basis of the recommendation provided by the USPSTF has seen the cases of breast cancer reduces in the country substantially.
  2. In assessing the situation on breast cancers which has he different prevalence rate based on age sentinel surveillance would be most appropriate. This is because the different cohorts will need to be assessed separately. The breast cancer situation according to the USPSTF recommendation would need to be considered different as such the different cohorts grouping will most likely make the assessment most viable and possible. In addition, the sentinel surveillance would give stratified and more categorical results on the situation of breast cancer based on age. 


Bammann, K., Peplies, J., De Henauw, S., Hunsberger, M., Molnar, D., Moreno, L. A., … & IDEFICS consortium. (2014). Early life course risk factors for childhood obesity: the IDEFICS case-control study. PloS one, 9(2), e86914.

Noppert, G. A., Wilson, M. L., Clarke, P., Ye, W., Davidson, P., & Yang, Z. (2017). Race and nativity are major determinants of tuberculosis in the US: evidence of health disparities in tuberculosis incidence in Michigan, 2004–2012. BMC public health, 17(1), 538.

Thompson, C. K., Eklund, M., & Esserman, L. J. (2015). Putting the” Great Mammography Debate” to Rest. AMERICAN JOURNAL OF HEMATOLOGY-ONCOLOGY, 11(9), 21-22.