“truth on top”

1. EBM Diagnosis paper cheat sheet “truth on top” sensitivity = true positives / total pts with disease = a/(a+c)specificity = true negatives / total pts without disease = d/(b+d) positive predictive value = true positives / total pts testing positive = a/(a+b)negative predictive value = true negatives / total pts testing negative = d/(c+d) positive likelihood ratio (LR+) = probability of + test in pts with disease / probability of + test in pts without disease = [a/(a+c)] / [b/(b+d]negative likelihood ratio (LR-) = probability of – test in pts with disease / probability of – test in pts without disease = [c/(a+c)] / [d/(b+d)] Ex: Probability 2/5 > Odds 2/7 x LR (4) = Odds 8/7 > Probability 8/15 AC 7.2.09 EBM Diagnosis paper cheat sheet “truth on top” sensitivity = true positives / total pts with disease = a/(a+c)specificity = true negatives / total pts without disease = d/(b+d) positive predictive value = true positives / total pts testing positive = a/(a+b)negative predictive value = true negatives / total pts testing negative = d/(c+d) positive likelihood ratio (LR+) = probability of + test in pts with disease / probability of + test in pts without disease = [a/(a+c)] / [b/(b+d]negative likelihood ratio (LR-) = probability of – test in pts with disease / probability of – test in pts without disease = [c/(a+c)] / [d/(b+d)] Ex: Probability 2/5 > Odds 2/7 x LR (4) = Odds 8/7 > Probability 8/15 AC 7.2.09