A 37-year-old man with a history of alcohol excess is admitted with alcohol-withdrawal seizures to the acute medical unit. Admission bloods show the following:
What other blood abnormality is he also most likely to have?
Correct Answer A: Hypomagnesaemia: Cause of low magnesium:
Features:
A study is designed to assess a new proton pump inhibitor (PPI) in elderly patients who are taking aspirin. The new PPI is given to 120 patients whilst a control group of 240 is given the standard PPI. Over a five year period 24 of the group receiving the new PPI had an upper GI bleed compared to 60 who received the standard PPI.
What is the absolute risk reduction?
Correct Answer D:
Numbers needed to treat and absolute risk reduction: Numbers needed to treat (NNT) is a measure that indicates how many patients would require an intervention to reduce the expected number of outcomes by one.
It is calculated by 1/(Absolute risk reduction) and is rounded to the next highest whole number.
Experimental event rate (EER) = (Number who had particular outcome with the intervention) / (Total number who had the intervention).
Control event rate (CER) = (Number who had particular outcome with the control/ (Total number who had the control).
Absolute risk reduction = CER-EER or EER-CER?
The absolute risk reduction (ARR) may be calculated by finding the absolute difference between the control event rate (CER) and the experimental event rate (EER). You will often find both versions of the above listed in different sources. In some ways in doesn't matter which you use as you will end up with the same answer but from a technical point of view:
*this may be more accurately termed absolute benefit increase, rather than absolute risk reduction
Which one of the following statements regarding the power of a study is correct?
Correct Answer A: Power = 1 - the probability of a type II error.
Significance tests: A null hypothesis (H0) states that two treatments are equally effective (and is hence negatively phrased). A significance test uses the sample data to assess how likely the null hypothesis is to be correct.
For example:
The alternative hypothesis (H1) is the opposite of the null hypothesis, i.e. There is a difference between the two treatments.
The p value is the probability of obtaining a result by chance at least as extreme as the one that was actually observed, assuming that the null hypothesis is true. It is therefore equal to the chance of making a type I error (see below).
Two types of errors may occur when testing the null hypothesis:
The power of a study is the probability of (correctly) rejecting the null hypothesis when it is false, i.e. the probability of detecting a statistically significant difference:
Immunoglobulin therapy may be indicated in each of the following except:
Correct Answer E: The management of management thrombotic thrombocytopenic purpura involves steroids and immunosuppressants. Plasma exchange is also commonly used.
Immunoglobulins: therapeutics: The Department of Health issued guidelines on the use of intravenous immunoglobulins in May 2008 Uses:
Basics:
A 64-year-old woman who is reviewed due to multiple non-healing leg ulcers. She reports feeling generally unwell for many months. Examination findings include a blood pressure of 138/72 mmHg, pulse 90 bpm, pale conjunctivae and poor dentition associated with bleeding gums.
What is the most likely underlying diagnosis?
Correct Answer C: Vitamin C deficiency: Vitamin C deficiency (scurvy) leads to defective synthesis of collagen resulting in capillary fragility (bleeding tendency) and poor wound healing.
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