Number Needed to Treat Calculation From a 2x2 Table
Calculates number needed to treat and 95 percent confidence intervals for data from a 2x2 table
nnt(Cell1, Cell2, Cell3, Cell4)
Cell1 |
Value for cases with a positive outcome |
Cell2 |
Value for cases with a negative outcome |
Cell3 |
Value for controls with a positive outcome |
Cell4 |
Value for controls with a negative outcome |
Number Needed to Treat and 95 percent confidence intervals
Mike Malek-Ahmadi
1. Cook RJ, Sackett DL. The number needed to treat: a clinically useful measure of treatment effect [published correction appears in BMJ 1995 Apr 22;310(6986):1056]. BMJ. 1995;310(6977):452-454.
2. Zar HJ, Cotton MF, Strauss S et al Effect of isoniazid prophylaxi on mortality of tuberculosis in children with HIV: randomised controlled trial. BMJ 2007; 136-9.
#Mortality data from Zar et al (2007) nnt(121, 11, 110, 21)
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