A 19-year-old female with a history of anorexia nervosa is admitted to hospital. Her BMI has dropped to 16. She has agreed to be fed by nasogastric tube.
Which one of the following electrolyte disturbances is most likely to occur?
Correct Answer D: Refeeding syndrome causes hypophosphataemia.
This patient is at risk of refeeding syndrome, which can lead to profound hypophosphataemia.
Hypophosphataemia: Causes:
Consequences:
Which one of the following statements regarding gastrin is true?
Correct Answer D:
Gastrointestinal hormones
Below is a brief summary of the major hormones involved in food digestion:
A case-control study is designed to investigate whether being exposed to passive smoking as a child is a risk factor for asthma. Two hundred patients with asthma are recruited. Of these 200, 40 report either one or both parents smoking in the house when they were a child. A further 200 controls who do not have asthma are recruited. Of these people 20 report that one or both parents smoked in the house.
What is the odds ratio of asthmatics having been exposed to passive smoking as a child?
Correct Answer A: Odds - remember a ratio of the number of people who incur a particular outcome to the number of people who do not incur the outcome.
NOT a ratio of the number of people who incur a particular outcome to the total number of people.
The odds of asthmatics being exposed to passive smoking is 40 / 160 = 1 / 4
The odds of the controls being exposed to passive smoking is 20 / 180 = 1 / 9
The odds ratio is therefore 1/4 / 1/9 = 9/4 = 2.25
Odds and odds ratio:
Odds are a ratio of the number of people who incur a particular outcome to the number of people who do notincur the outcome. The odds ratio may be defined as the ratio of the odds of a particular outcome with experimental treatment and that of control.
Odds ratios are the usual reported measure in case-control studies. It approximates to relative risk if the outcome of interest is rare.
For example, if we look at a trial comparing the use of paracetamol for dysmenorrhoea compared to placebo we may get the following results:
The odds of achieving significant pain relief with paracetamol = 40 / 20 = 2
The odds of achieving significant pain relief with placebo = 30 / 60 = 0.5
Therefore the odds ratio = 2 / 0.5 = 4
A randomized controlled trial compares two drugs used in the initial management of rheumatoid arthritis. After being assigned to the randomized groups a number of patients drop out due to adverse effects of the medication.
How should the data be analyzed?
Correct Answer C: Intention to treat analysis
Intention to treat analysis is a method of analysis for randomized controlled trials in which all patients randomly assigned to one of the treatments are analysed together, regardless of whether or not they completed or received that treatment.
Intention to treat analysis is done to avoid the effects of crossover and drop-out, which may affect the randomization to the treatment groups.
Which one of the following would invalidate the use of the Student's t-test when performing a significance test?
Correct Answer B: Data must be parametric, i.e. follows a normal distribution.
Significance tests: types: The type of significance test used depends on whether the data is parametric (something which can be measured, usually normally distributed) or non-parametric.
Parametric tests:
Non-parametric tests:
Paired data refers to data obtained from a single group of patients, e.g. Measurement before and after an intervention. Unpaired data comes from two different groups of patients, e.g. Comparing response to different interventions in two groups.
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