A systematic review of the literature was undertaken comparing proton pump inhibitors with H2- receptor blockers for the prevention of gastro-intestinal bleeding in ICU patients.
The following figure was included:
a) Name the type of graph illustrated in the above figure. (10% marks)
b) What does it show? (25% marks)
c) What are the benefits of this type of analysis? (25% marks)
d) What are the disadvantages of this analysis? (40% marks)
Combining the trials together, PPI use results in an odds ratio of 0.35 or reduction in the risk of bleeding compared to H2RA. Alternatively, PPI use results in 65% reduction (1- 0.35) in bleeding.
Combines small studies with limited power, increasing the number and thus the ability to pick up a positive effect. Small studies with low power (due to small effect, small numbers) run the risk of a Type II error.
Individual studies might have different patient populations (with different risk of bleeding) or different definitions of outcome.
Individual studies might have been conducted with different degrees of rigour (blinding, etc.)
There is publication bias to positive studies so that negative studies are not reported. Need full disclosure how the studies were selected, their scientific grading, subgroup analyses and assessment of heterogeneity.
Pass rate: 83%
Highest mark: 8.0
Candidates who scored well showed an in-depth understanding of the applied physiology and consequences of the various therapeutic options. Candidates who scored poorly omitted key points.