Epidemiology: Observational Studies and Study Designs

This article discusses observational studies and study designs in epidemiology. It explains the advantages and disadvantages of cross-sectional, cohort, and case-control studies. It also explores the association between depression and binge eating, detention on asylum seekers, folate supplementation during pregnancy, and Alzheimer's disease.

Running head: EPIDEMIOLOGY 1
Epidemiology
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EPIDEMIOLOGY 2
Part 1
The Cohort, cross-sectional along with case-control studies are usually referred to as
observational studies. However, these happens to be the only practicable methods to study
different issues. Cross-sectional studies are used to determine prevalence (Last, Abramson &
Freidman, 2016). Additionally, they are generally quick and easy but do not allow a distinction
between cause and effect. On the other hand, the cohort studies are usually utilized in the study
of the incidence, causes along with prognosis (Johnson & Onwuegbuzie, 2014)
Causality is not a property which is contained in data and hence the only way to address
it is to perform a controlled experiment. The causal relation can only be hypothesized if there is
only observational data. Conversely, the correlation of the respective variables would then be in
accordance with such speculation but cannot proof.
The most appropriate approach to examining causation is to perform a controlled
experiment where we can be aware of the priority which only the arbitrarily changed conditions
can be responsible for a possible change in the response (Robins, Hernan & Brumback, 2016).
This involves the researcher determining the kind of individuals who were exhibited to the agent
or treatment or the prevalence of a variable within every study groups. Furthermore, when
compared with cohort and cross-sectional studies, the case-control are usually retrospective
Conversely, if there is only one observable data, then the causal relations can only be
speculated (Greenland, 2014). In that case, the correlation of the receptive variables would then
be by such speculations though will not be a proof and lack of association would not imply the
absence of causal relation.
Part 2

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The association between depression and binge eating in obese adolescents and adults.
The cross-sectional study design is used in studying prevalence of different events along
with diseases. Accordingly, it establishes the association among two variables. Therefore, the
most suitable study design in the association between depression and binge eating in obese
adolescents along with adults is a cross-sectional study design (Sarnak ital. 2013).
However, adolescence is the most critical stage where one develops a positive or
negative body image. Accordingly, gaining excessive weight because of indulging in binge
eating usually results in obesity. In that case, it may result in weight-related bullying that
contributes further to dissatisfaction surrounding body parts and further depression. Since this
phenomenon is widely prevalently affecting the mental behavior of both obese adolescents and
adults and at risk of chronicity, it is, therefore, advantageous study design (Rothman, Greenland
& Lash, 2015).
Factors which usually plays a role in the etiology of obesity are generic, physiological
and behavioral. Conversely, all these factors are to be taken into consideration as the selected
study is looked into (Franco, Duarte-Franco, & Ferenczy, 2014). The randomized control study
is an experimental study design and in this case the cases are randomly assigned to two groups
where one receives the treatment while the other one gets the placebo. Conversely, the study is
conducted according to the redefined protocol.
The long-term effects of detention on the mental and physical health of asylum
seekers.
The Cohort study design is suitable in this case. As an illustration, the asylum seekers is
termed as someone whose petition for shelter in a host country is not processed yet (Baron et al.,
2015). However, it's stated that the rights for every individual to find and enjoy in other Nations

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asylum if it is due to persecution in particular because of a well-founded fear in consideration of
account of their race, religion, nationality, and membership in a specific social group (Rothman,
Greenland & Lash, 2015).
Detention of asylum seekers in other nations usually involves administrative procedures
along with the domestic legal system. The asylum seeker may find some relief even if the
detention is for long-term thinking which he/she could at least escape religious persecution. In
that case, a sense of security might prevail (Sarnak, e.tel).
Folate supplementation during pregnancy and development of autism in offspring.
The case-control study design is most appropriate in this case. The main advantages of
folate supplementation are as highlighted below (Last, Abramson & Freidman, 2016). The first
one is that it regularly prevents two common and severe congenital disabilities, spina bifida, and
anencephaly. The second advantage is that it reduces the risk of neural tube defects in children
(Rothman, Greenland & Lash, 2015). On the other hand, its disadvantage is that the risk of
autism since there is an inverse association between the use of folate and the subsequent risk of
autism.
The cohort studies are utilized in studying incidences, causes along with forecasts. This is
due to the fact that they usually measure events in chronological order and hence can be utilized
in distinguishing between cause and effect. However, it is the best method to determine the
incidence on a condition. On the other hand, the cross sectional studies usually determine the
prevalence. They are usually quick but does not allow distinction between causes and effects
(Rothman, Greenland & Lash, 2015).
Testing a drug for use in older adults diagnosed with Alzheimer¡¦s Disease.

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The randomized controlled trial is most suitable in this case. The advantage of this is that
the Alzheimer's disease is a neurodegenerative disease which affects a wide range of people.
Even though there is a lack of suitable biomarker, psychometric instruments are available for the
measurements in clinical trials (Franco, Duarte-Franco, & Ferenczy, 2014). This instrument is
utilized in measuring effects of drugs for Alzheimer’s diseases and hence there is an analysis that
Centers for medicine within the public interest groups in the United States has set aside enough
funds for AD drugs which is justifiable economically.
On the other hand, the main disadvantage is that AD is a progressive disease which
worsens during trial, further complicating interpretation of results which are studied. Moreover,
there is a limitation in the methodology of the clinical trials leading to lack of substantial
benefits. Accordingly, the drug is not cost effective though it has some efficacy but hence with
limited effectiveness for patients (Rothman, Greenland & Lash, 2015).
References
Baron, J. A., Karagas, M., Barrett, J., Kniffin, W., Malenka, D., Mayor, M., & Keller, R. B.
(2015). Basic epidemiology of fractures of the upper and lower limb among Americans
over 65 years of age. Epidemiology, 612-618.
Franco, E. L., Duarte-Franco, E., & Ferenczy, A. (2014). Cervical cancer: epidemiology,
prevention and the role of human papillomavirus infection. Canadian Medical
Association Journal, 164(7), 1017-1025.
Greenland, S. (2014). Dose-response and trend analysis in epidemiology: alternatives to
categorical analysis. Epidemiology, 356-365.

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Johnson, R. B., & Onwuegbuzie, A. J. (2014). Mixed methods research: A research paradigm
whose time has come. Educational Researcher, 33(7), 14-26.
Last, J. M., Abramson, J. H., & Freidman, G. D. (Eds.). (2016). A dictionary of
epidemiology (Vol. 4). New York: Oxford University Press.
Robins, J. M., Hernan, M. A., & Brumback, B. (2016). Marginal structural models and causal
inference in epidemiology.
Rothman, K. J., Greenland, S., & Lash, T. L. (2015). Modern epidemiology.
Sarnak, M. J., Levey, A. S., Schoolwerth, A. C., Coresh, J., Culleton, B., Hamm, L. L., ... &
Parfrey, P. (2013). Kidney disease as a risk factor for the development of cardiovascular
disease: a statement from the American Heart Association Councils on Kidney in
Cardiovascular Disease, High Blood Pressure Research, Clinical Cardiology, and
Epidemiology and Prevention. Circulation, 108(17), 2154-2169.