Epidemiology Assignment: Evaluation of Heart Attack Causes and Studies

This epidemiology assignment delves into the analysis of heart attack risk factors, examining sufficient cause sets and identifying individuals at high risk based on provided diagrams and data. The assignment also reviews a systematic review and meta-analysis on coffee consumption and its association with hepatocellular carcinoma and chronic liver disease, evaluating experimental evidence, temporality, strength of association, dose response, biological plausibility, and consistency. Furthermore, it addresses a research question on the effectiveness of surgical interventions for neurological conditions, discussing the roles of mediators and colliders in a directed acyclic graph (DAG). Finally, the assignment examines a review paper comparing pharmacological and non-pharmacological treatments for gestational diabetes, specifically comparing metformin and insulin, and analyzing relative risks and outcomes such as preterm birth and neonatal complications, along with a discussion of the limitations and implications of the research.

Running Head: EPIDEMIOLOGY
Epidemiology
Name of Student:
Name of University:
Author Note:

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1.
a) The necessary components of heart attack based on the diagram provided includes-
Male gender, High Cholesterol, High blood pressure, Smoking, Diabetes,
unhealthy diet, older age, being inactive and overweight.
b) Four candidates that contribute to heart attack includes high cholesterol, high blood
pressure, smoking and male gender. This is because the artery becomes hardened
with cholesterol deposition and it becomes difficult for the heart to pump blood to
the arteries. And smoking damages the lining of the arteries and builds up fatty
material deposition in the arteries narrowing them. And males are more at risk to
heart diseases because of traditional risk issues.
c) The person F is at highest risk of a heart attack first amongst the 7 different people
considered in the cohort study.
d) The systematic review and meta-analysis by Bravi et al (2017) proves the
following-
Seria
l No.
Criteria Evaluation
1. Experimental
evidence
This meta-analysis had a lot of literature review of coffee
promoting reduction in HCC and CLD which includes 15
effective studies that included 3414 cases of
hepatocellular carcinoma and 1463 cases of chronic liver
disease. The meta-analysis shows that 34% and 38%
reduction in the risk of hepatocellular carcinoma and
chronic liver disease respectively for individual who
regularly intake coffee in comparison to non derinkers or
occasional drinkers
2. Temporality The studies revealed that intake of coffee helps in
reduction of the probability of liver cancer and chronic
liver diseases. The relative risk for individual who drink
coffee frequently is 0.50 and 0.35 for HCC and CLD
respectively.
3 Strength of
association
A large number of cases with liver cancer and CLD that
was included (12 studies on HLC and 6 studies on CLD)
as well as the several studies that considered the

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categories like intake of coffee guided the research to
explore factors like the levels of the coffee consumption
and the different population involved in that were the
main strengths of the meta-analysis.
4 Dose
response
The relative risk for HCC was 0.66, 0.72 and 0.50 for
regular drinkers, occasional drinkers and frequent
drinkers respectively. The relative risks for the increased
consumption of one cup per day was 0.85. The
summative RR for CLD was 0.62 for regular drinkers, it
was 0.72 for occasional drinkers and 0.35 for frequent
drinkers and the relative risk for an increment of one cup
for one day was 0.74.
5 Biological
plausibility
A strong oxidative activity is maintained by coffee. This
activity prevents the proliferation of liver carcinoma cells
(Bamia et al., 2015). This effect of protection by intake of
coffee can be observed among health concerned
population and also in patients suffering chronic liver
diseases, it is also observed that the intake of coffee also
prevents liver cirrhosis. It reduces the serum level of
enzymes glutamyl transferase and aminotransferase
which are indicators of hepatic disorders (Kennedy et al.,
2017).
6 Consistency The relative risk was 0.66 based on the Asian and
European studies. The studies showed related risk rates
though in those countries the consumption of coffee was
low.
e) It can be concluded from the provided research article that coffee helps in
preventing liver cancer with the fact that the antioxidative characteristic of coffee

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prevents proliferation of the liver cancer cells and thus contributes to preventing
liver cancer (Wiltberger et al., 2019).
2.
a)
The research question for this study was to understand the efficacy of the new
surgical intervention on mortality due to the neurological conditions by analysing
the observational study data.
b)
c)
d) The symptom severity amongst the given variables in the DAG represent as the
mediator.
e) The collider represents the. age in the relationship amongst the variables in the
DAG.
f) The researchers should adjust the age variable in the statistical model to estimate
the effectivity of the surgical intervention.
Life threatening
neurological
condition
Increased rate of
mortality in
patients
A new surgical
intervention
aided in
improvement of
the survival
rates.
Life threatening
neurological
condition
Symptom
Severity in the
affected patients
A new surgical
intervention aided in
improvement of the
survival rates.
Patient dies
after no
improvement
post the surgery
Life
threatening
neurologica
l condition
Symptom
Severity in the
affected
patients
A new surgical
intervention
aided in
improvement of
the survival
rates.
The age of the
patient
determines
whether to
move in for
surgical
intervention
Patient dies
after no
surgical
intervention

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g) The adjusted relative risk refers to the statistical analysis obtained when the
incidence of the neurological disorder in rare that is less than 10%. The adjusted
odds ratio yielded by the logistic regression approximates the relative risk. This
sometimes may show dramatical overestimation of the relative risk. According to
the statement the unadjusted relative risk of the confounder was 0.75 which states
the relative risk when the disease occurrence is more than 10%. Thus, it determines
that the probability of the positive impact of the intervention is high.
3.
a) The review paper talks about two types of exposures a pharmacological approach
that involved exposure of the patients with insulin and glibenclamide or
metformin. And a non-pharmacological exposure where the dietary changes and
routine palliative care was given to the patients.
b) An example of a maternal outcome examined for the treatment with metformin
versus insulin is pre-eclampsia which is a medical condition in a pregnant woman
characterised by high blood pressure, protein loss in urine and swollen hands and
feet. A health comprised condition of a neonatal post metformin versus insulin
treatment is macrosomia which is a condition of the new born whose size is larger
than the average.
c) The study of this systemic analysis involved randomized control trials that
included women diagnosed with gestational diabetes mellitus or impaired glucose
tolerance were randomised to a treatment aimed to reduce the blood glucose level.
d) The studies show that women with gestational diabetes mellitus are not associated
with perinatal complication in comparison to administering insulin. A randomised
controlled trial of 363 women who had gestational diabetes was selected. 92.6% of
the individuals received metformin until delivery and the rest 43.6% received
supplemental insulin. The rate of primary composite outcome is 32% in the group
that was administered metformin and 32.2% in the groups that received insulin.
Research studies infer that women with gestational diabetes prefer to intake
metformin in comparison to insulin.
e)
Preterm birth
Exposure Yes No
Metformin 44 319

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insulin 28 342
f)
Preterm birth
Exposure
Yes No Total
Cumulative
Incidence
Relative
Risk
Metformi
n 44 319 363 12.10%
1.60insulin 28 342 370 7.56%
Thus, the relative risk states that the drug metformin is more effective than Insulin.
g) The relative risk of the women is 1.00 with coincidence interval of 95%. This
indicates the metformin is indeed better and preferred by the patients in
comparison to insulin.The studies of Rowan et al 2008 RCT and Farrar et al 2017
conclude the same things stating the effects of insulin is more and hence metformin is
more safe for keeping the blood glucose level under control in comparison to the insulin to
avoid incidence of preterm birth. The primary outcome of neonatal complications did
not have much significant difference between the groups being treated with
metformin and insulin showing 32% and 32.2% complications based on the data
(Rowan et al., 2008). The instance of severe hypoglycemia was less frequent in the
metformin group but preterm birth was more frequent. There was an observed
delivery before 32 weeks of gestation observed.
h) The random sequence generation was considered to be at low risk however many
of the publications suggested it to be unclear but there was no potential of high risk
of the random sequence generation. The completeness of the outcome data showed
a lower risk of the cumulative study of the allocation concealment and the blinding
of participants.
i) The screening for publication bias was considered but tests were not performed
since the number of trials in the meta-analysis was insufficient for the screening to
be reliable.
j) It can be concluded from the review article that dietary changes and lifestyle
changes and care can aid in reducing the blood glucose level. Additional

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supplements of metformin may help the individual to sustain the blood glucose
level with minimal or no complications.
k) The limitations of the meta-analysis review article included the poor trial quality
with the risks of high and unclear bias. And for some of the comparisons the trials
and the number of women concerned were few as per the outcomes.
l) The main implication of the article is that it reassures that dietary as well as
lifestyle advice is the initial step of the care for gestation diabetes. Supplements of
metformin or insulin aids in further control of the blood glucose level (Balsells et
al., 2015) if the levels are elevated post dietary and lifestyle care to prevent the risk
of LGA.
m) The individual dots in the graph represents single studies performed (Sedgwick &
Marston, 2015). The funnel plot is exploited to understand the potential publication
bias visually (Sedgwick, 2015). It shows the effect of the treatment plotted against
the reciprocal of its standard error. In this study the outcome of each study
influences the publication. This is a clear asymmetric funnel plot which indicates
the relationship between the treatment effect estimates made in the meta-analysis
and the study precision of the article.

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References
Bamia, C., Lagiou, P., Jenab, M., Trichopoulou, A., Fedirko, V., Aleksandrova, K., ... &
Boutron‐Ruault, M. C. (2015). Coffee, tea and decaffeinated coffee in relation to
hepatocellular carcinoma in a E uropean population: Multicentre, prospective cohort
study. International journal of cancer, 136(8), 1899-1908.
Kennedy, O. J., Roderick, P., Buchanan, R., Fallowfield, J. A., Hayes, P. C., & Parkes, J.
(2017). Coffee, including caffeinated and decaffeinated coffee, and the risk of
hepatocellular carcinoma: a systematic review and dose–response meta-analysis. BMJ
open, 7(5), e013739.
Wiltberger, G., Wu, Y., Lange, U., Hau, H. M., Tapper, E., Krenzien, F., ... & Broschewitz, J.
(2019). Protective effects of coffee consumption following liver transplantation for
hepatocellular carcinoma in cirrhosis. Alimentary pharmacology & therapeutics, 49(6),
779-788.
Sedgwick, P. (2015). What is publication bias in a meta-analysis?. Bmj, 351, h4419.
Sedgwick, P., & Marston, L. (2015). How to read a funnel plot in a meta-analysis. Bmj, 351,
h4718.
Balsells, M., García-Patterson, A., Solà, I., Roqué, M., Gich, I., & Corcoy, R. (2015).
Glibenclamide, metformin, and insulin for the treatment of gestational diabetes: a
systematic review and meta-analysis. Bmj, 350, h102.
Rowan, J. A., Hague, W. M., Gao, W., Battin, M. R., & Moore, M. P. (2008). Metformin
versus insulin for the treatment of gestational diabetes. New England Journal of
Medicine, 358(19), 2003-2015.