Can J Emerg Med
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Acute upper gastrointestinal (UGI) hemorrhage is a common, often serious condition encountered in the emergency department (ED). Previous research has suggested that transfusion of blood products may interfere with the hypercoagulable state induced by significant blood loss. Our objective was to determine whether the frequency of rebleeding is higher in patients with UGI bleeding who have received early blood transfusion. ⋯ Our results support previous research suggesting that transfused UGI bleed patients have a higher rate of rebleeding. However, because of the retrospective design, causality cannot be inferred.
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The authors of studies often report their results using abbreviated terms such as RR, OR, ARR, RRR and NNT. These terms are quantities that express the strength of association between the dependent and independent variables and are collectively referred to as measures of association. The similarity between these measures and the multiple terms by which each is referred can be confusing. The purpose of this article is to explain in a straightforward manner the purpose, derivation, and limitations of some of the more commonly used categorical measures of association, including relative risk, odds ratio, absolute and relative risk reduction and number needed to treat, using results from recent emergency medicine studies published by Canadian researchers.