Key to statistical result interpretation: P-value in plain English Why should students know about kappa value?Įfficacy of drugs: 3 examples to get you to truly understand Number Needed to Treat (NNT) You may also be interested in these blogs: The correct answer is A.īringing it all together – Real world example. I do hope you enjoyed working through this and would appreciate any feedback on the content, design and presentational aspects of this tutorial.Ĭoncept check 1. However it should be stressed that any results are only valid if the study was well designed and conducted, which highlights the importance of critical appraisal as a key feature of evidence based medicine. This is a very basic introduction to interpreting odds ratios, confidence intervals and p values only and should help healthcare students begin to make sense of published research, which can initially be a daunting prospect. This result was statistically significant. This result was statistically significant.Ĭ) The odds of death, myocardial infarction, ischemia-driven revascularization, or stent thrombosis at 48 hours after randomization in the Cangrelor arm were 22% less than in the Clopidogrel arm with the true population effect between 34% and 7%. This result was not statistically significant.ī) The odds of death, myocardial infarction, ischemia-driven revascularization, or stent thrombosis at 48 hours after randomization in the Cangrelor arm were 34% less than in the Clopidogrel arm with the true population effect between 7% and 22%. The results section reported “The rate of the primary efficacy end point was … (adjusted odds ratio with Cangrelor, 0.78 95% confidence interval, 0.66 to 0.93 P=0.005)Ī) The odds of death, myocardial infarction, ischemia-driven revascularization, or stent thrombosis at 48 hours after randomization in the Cangrelor arm were 22% less than in the Clopidogrel arm with the true population effect between 34% and 7%. How to do odds ratios with rxc groups on spss on mac trial#This result was equivocal.Ī drug company-funded double blind randomised controlled trial evaluated the efficacy of an adenosine receptor antagonist Cangrelor vs Clopidogrel in patients undergoing urgent or elective Percutaneous Coronary Intervention (PCI) who were followed up for specific complications for 48 hrs as outlined in the diagram below (Bhatt et al. This result was not statistically significant.Ĭ) The odds of death in the SuperStatin arm are 50% less than in the placebo arm with the true population effect between 60% and 40%. This result was statistically significant.ī) The odds of death in the SuperStatin arm are 50% less than in the placebo arm with the true population effect between 60% and 40%. So if the trial comparing SuperStatin to placebo stated OR 0.5 95%CI 0.4-0.6 p<0.01Ī) The odds of death in the SuperStatin arm are 50% less than in the placebo arm with the true population effect between 60% and 40%. If the OR is 0.05 indicates there is not a statistically significant difference between groups. If the OR is > 1 the control is better than the intervention. So if the outcome is the same in both groups the ratio will be 1, which implies there is no difference between the two arms of the study. The denominator is the odds in the control or placebo arm = Odds Ratio (OR) The numerator is the odds in the intervention arm So when researchers calculate an odds ratio they do it like this: The scenario for this tutorial is centred around the diagram below, which outlines a fictional parallel two arm randomised controlled trial of a new cholesterol lowering medication against a placebo.Īn odds ratio is a relative measure of effect, which allows the comparison of the intervention group of a study relative to the comparison or placebo group. This short tutorial aims to introduce healthcare students to the interpretation of some of the most commonly used statistics for reporting the results of medical research. The first steps in learning to understand and appreciate evidence-based medicine are daunting to say the least, especially when confronted with the myriad of statistics in any paper. Contents:īringing it all together – Real world example How to do odds ratios with rxc groups on spss on mac how to#How long will it take?Ī statistical textbook reworded or how to calculate any of these statistics. How to interpret odds ratios, confidence intervals and p values with a stepwise progressive approach and a’concept check’ question as each new element is introduced. Students of medicine or from the clinical sciences and professions allied to medicine wanting to enhance their understanding of medical literature they will encounter throughout their careers.
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