Evidence Based Medicine
Evidence Based Medicine
GlossaryLikelihood Ratio is the likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that the same result would be expected in a patient without that disorder. Meta-analysis is an overview which uses quantitative methods to summarise the results. Negative Predictive Value (-PV) is the proportion of people with a negative test who are free of disease. Number Needed to Treat (NNT) is the number of patients who need to be treated to prevent one bad outcome in a period of time. It is the inverse of the ARR: NNT = 1/ARR. Odds are a ratio of events to non-events. If the event rate for a disease is 0.1 (10 per cent), its nonevent rate is 0.9 and therefore its odds are 1:9, or 0.111. Note that this is not the same expression as the inverse of event rate. Odds Ratio describes the odds of an experimental patient suffering an adverse event relative to a control patient. Overview is a systematic review and summary of the medical literature. Positive Predictive Value (+PV) is the proportion of people with a positive test who have disease. Randomised Controlled Clinical Trial a group of patients is randomised into an experimental group and a control group. These groups are followed up for the variables / outcomes of interest. Relative Risk Reduction (RRR) is the percent reduction in events in the treated group event rate (EER) compared to the control group event rate (CER): RRR = (CER - EER) / CER * 100 Risk Ratio is the ratio of risk in the treated group (EER) to the risk in the control group (CER): RR = EER/CER. RR is used in randomised trials and cohort studies. Sensitivity is the proportion of people with disease who have a positive test. Specificity is the proportion of people free of a disease who have a negative test. |
