Diagnostic-Test

							EVIDENCE BASED MEDICINE VALUE CALCULATOR Diagnostic Test 1. ENTER THE DATA INTO EACH CELL
Disease Present Positive test Negative test Disease Absent

24 8

1 12

2. SEE THE RESULTS
Results: Persons with a positive test and have the disease Persons with a positive test and do not have the disease Persons with a negative diagnostic test who have the disease Persons with a negative diagnostic test who do not have the disease All persons who have a postivie diagnostic test All persons who have a negative diagnostic test All persons who have the disease All persons who do not have the disease Total number of patients Pre-test probability or Prevalence Pre-test odds Sensitvity Specificity False negative rate False positive rate Positive predictive value Negative predictive value Liklihood ratio for a positive test Liklihood ratio for a negative test Post-test odds Post-test probability 24 1 8 12 25 20 32 13 45 71% 2.46 75% 92% 25% 8% 96% 60% 9.75 0.27 24.00 96% Upper 90% 107%

Not Sensitive enough Acceptable

Moderate Small but important

95% Confidence Interval for sensitivity (+/-) 95% Confidence Interval for specificity (+/-)

Lower 60% 78%

8984b954-1f52-4b24-92b5-bb6381154307.xls

11/27/2009

EVIDENCE BASED MEDICINE VALUE CALCULATOR

8984b954-1f52-4b24-92b5-bb6381154307.xls

11/27/2009

EVIDENCE BASED CALCULATOR VALUE CALCULATOR Therapeutic Study 1. ENTER THE DATA INTO EACH CELL
Outcome Occurs Therapy Done Therapy Not Done Outcome Doesn't Occur

2 3

8 7

2. SEE THE RESULTS
Results: Patients given treatment who have the outcome Patients given treatment who do not have the outcome Patients not given a treatment but have the outcome Patients not given the treatment and who do not have the outcome Experimental group Control group All patients with the outcome All patients who do not have the outcome Total number of patients Risk of events among patients receiving therapy Risk of events among controls without therapy (PEER) Relative Risk Relative Risk Reduction Absolute Risk Reduction Number Needed To Treat SEln(RR) LL95ln(RR) UL95ln(RR) LL95raw UL95raw 2 8 3 7 10 10 5 15 20 20% 30% 67% 33% 10% 10 0.80 -1.97 1.15 0.14 3.17 Upper 86.0% 48% 2.1 Lower -217.20% -27.70% -3.6

95% Confidence Interval on a Relative Risk Reduction 95% Confidence Interval on an Absolute Risk Reduction 95% Confidence Interval on a Number Needed To Treat

8984b954-1f52-4b24-92b5-bb6381154307.xls

11/27/2009

EVIDENCE BASED MEDICINE VALUE CALCULATOR Harm, Causation, Etiology 1. ENTER THE DATA INTO EACH CELL
Outcome Occurs Exposure No Exposure Outcome Doesn't Occur

30 14

161 65

2. SEE THE RESULTS
Results: Patients with adverse outcome and exposed Patients who do not develop an adverse outcome but were exposed Patients with adverse outcome and not exposed to treatment Patients without adverse outcome and who were not exposed Total exposed Total not exposed Patients who had the outcome of interest Patients who did not have the outcome of interest Total number of patients Odds that a patient exposed to treatment will have the outcome of interest Odds that a patient not exposed to treatment will have the outcome of interest Odds ratio Relative Risk SEln(OR) LL95ln(OR) UL95ln(OR) LL95raw UL95raw Absolute Risk Increase Number Needed To Harm 30 161 65 14 191 79 44 226 270 0.19 0.22 0.87 0.89 36% -84% 55% 43% 174% 0.02 49.6 Upper 12% 8.4

Not Significant Not Impressive

95% Confidence Interval on Absolute Risk Increase 95% Confidence Interval on Number Needed To Harm

Lower -8% -12.7

8984b954-1f52-4b24-92b5-bb6381154307.xls

11/27/2009