Answers to abstract 1

Last updated: Monday, September 21, 2015

a) What is the implication of allocation being 'centralised'?
It means that the allocation was carried out in a central location away from the study centre(s) and so it was fully concealed from researchers and participants, who therefore had no influence on the choice of study group.

b) What are the absolute risks of VTE in the enoxaparin and placebo groups?  
The absolute risk (AR) of a VTE in the enoxaparin group is 2.5% and in the placebo group is 4%.

c) What are the absolute risk reduction and relative risk reduction? What do these numbers tell us?
ARR = 4% – 2.5% = 1.5%
RRR = (4% - 2.5%) / 4% = 37.5%
ARR: extended-duration enoxaparin reduced the risk of VTE by 1.5%.
RRR: extended-duration enoxaparin reduced the risk of VTE by 37.5% compared to placebo.

d) What are your initial conclusions about the results of this trial?
Based on just the abstract, which is not best practice, we could say that extended-duration prophylaxis with enoxaparin was more effective than placebo at reducing the risk of venous thromboembolism (VTE) in this group of patients. Major bleeding events look to be more common with enoxaparin than placebo. 

e) What other information, not included in the abstract, would you need to know to be able to appraise this paper?
Amongst other things, you need to look at the baseline characteristics of the groups, the exclusion and inclusion criteria, how many people they needed in each group, what were included in the outcomes of ‘VTE’ and ‘major bleeding events’, how the outcomes were measured and side effect profiles.