Table 1

Measures of treatment efficacy from the randomised controlled trials in rheumatoid arthritis (RA)*

Etanercept v placebo2Drug A v placebo (a hypothetical study)
VariableTreatment groupPlacebo groupTreatment groupPlacebo group
*Adapted from reference 7.
AEs, adverse events
Group size (n)7880
Number not met ACR50 improvement (n)3875
Risk for treatment failure0.487 (X)0.938 (Y)0.0026 (X)0.005 (Y)
Relative risk (X/Y)0.520.52
Relative risk reduction ((Y−X)/Y or 1−X/Y)0.480.48
Absolute risk reduction ([|]Y−X[|])0.450.0024
Number needed to treat (1/[|]Y−X[|])2.2416.7
Number of withdrawals due to AEs23
Risk for withdrawal0.026 (a)0.038 (b)
Number needed to harm (1/[|]b−a[|])83.3