ESA 1 - 2007 Paper 1

Question 1

Give the biochemical explanation for weight loss, thirst and fatigue commonly seen in type 1 diabetes (5).

Answer 1

Weight loss: - Through breakdown of fat due to impaired glucose uptake (1) and through breakdown of muscle due to impaired glucose uptake (1).
Polyuria: - Excess glucose causes osmotic drag of water from the tissue in to the blood (1) leading to increased filtration rate to reduce water content of the blood (1).
Fatigue: - Lack of readily accessible carbohydrate (1).

Question 2

Name six different biochemical pathways/processes that are stimulated by insulin and seven pathways that are inhibited by insulin.

Answer 2

Stimulated: Lipogenesis; glycolysis; glycogen synthesis; protein synthesis; glucose uptake; K+ uptake.

Inhibited: Lipolysis; gluconeogenesis; glycogenolysis; protein breakdown; cellular dehydration; fat oxidation; ketogenesis.

Question 3

List three hormones that counter-act some of the actions of insulin.

Answer 3

Glucagon; cortisol; adrenaline

Question 4

Children under 16 are sometimes allowed to give their own consent to medical treatment. List the four attributes about the young person that need to be considered.

Answer 4

Chronological age
Mental/emotional maturity
Intelligence
Comprehension

Question 5

Under what circumstances should a health professional providing health care for a 14 year old breach confidentiality and report what has been said to authorities? (6)

Answer 5

• When she or someone else under 16 is being sexual abused.
• When she or someone else under 16 is being neglected (child abuse).
• When she or someone else under 16 is being emotionally abused.
• When she or someone else under 16 is being physically abused.
• When she has been involved in a serious crime (eg. rape).
• When she reports that someone else has been involved in a seroius crime or intending to commit a serious crime (eg. rape).

Question 6

Describe the different social and/or practical barriers that may prevent a patient from seeking medical attention sooner? (7)

Answer 6

Geographical barriers (eg. distance to surgery);
Physical barriers (eg. disability);
Material barriers (eg. no transport/can’t afford time off work);
Social barriers (eg. caring for someone else/gender issues/issues related to lay beliefs);
Cultural barriers (eg. language/lack of male GP);
Beliefs about ilness;
Beliefs about attendance at GP surgery.

Question 7

For what possible reasons is it important to the patient to be told of bad news (don’t include ‘to reduce doctor stress’). (5)

Answer 7

To maintain trust; to reduce uncertainty; to allow realistic life planning; to allow appropriate adjustment; to promote open communication.

Question 8

What is a case control study (2)?

Answer 8

A case control study is an observational study, which defines cases with a certain disease and has a group of controls without the disease (1). The study then looks back at the possible exposures to ascertain what proportion in each group has been exposed to the agent of interest (1).

Question 9

What does an odds ration of 13.5 mean with regard to exposure to chemical X and the development of cancer?

Answer 9

The odds of developing cancer is 13.5 times higher in those exposed to chemical X.

Question 10

Interpret a 95% confidence interval of 5.6 to 32.4, if the odds ratio = 13.5.

Answer 10

This means there is a 95% chance that the true odds ration lies between 5.6 and 32.4. The result is statistically significant at p<.05 because the 95% confidence interval range is above 1. The null hypothesis can therefore be rejected.

Question 11

What is meant by ‘randomised’ when refering to a double blinded placebo controlled randomised trial? Why is ‘randomised’ an important feature?

Answer 11

Randomised = random allocation of treatment (by a procedure analogous to flipping a coin). Each patient therefore has an equal chance of being allocated the three treatments.

‘Randomised’ is important to minimise allocation bias and subsequent confounding.

Question 12

What is meant by ‘double-blind’? Why is blinding important?

Answer 12

Double-blind refers to two or more of the patient, clinitian or assessor not knowing the treatment allocation.

Blinding is important because knowledge of the treatment allocation may bias the results; the clinician may alter other treatment, care and interest in the patient; the patient may change their behaviour, expectations of outcome etc. as a result of knowing (placebo effect); the clinician/investigator assesing the effects may alter their approach when assessing outcomes (reporting bias).

Question 13

What is a placebo (1)? Why is it an important feature of randomised control trials (1)? What are the ethical implications of using a placebo (3)?

Answer 13

A placebo is an inert substance that looks, tastes and is packaged identically to the comparison drug.
Placebos are important to assess the ‘placebo affect’ ie. the psychological benefit from being looked after better/in a different way. The use of placebo eliminates the placebo effect.
Ethics: Patient must be fully informed and understand they may recieve placebo; there must be ‘clinical equipoise’ between the placebo vs. the drug being trialled ie. genuine belief that don’t know which is better; placebo should only be used when no ‘standard treatment’ is availible to compare the new treatment to.

Question 14

What does ‘intention to treat’ analysis mean? What is the alternative way to analyse the data? Why might it better to analyse on an intention to treat basis?

Answer 14

Intention to treat analysis loos at the groups as they were randomised, ignoring whether or not they took the drug. Non-compliers are therefore included in the analysis. Trials analysed in this way are called pragmatic trials.
The alternative is to analyse the data of those that completed the treatments only (‘as-treated’ analysis).
Intention to treat is better as this looks at the ‘real world’ effect of treatment ie. what will happen in clinical practice.