When a clinical trial is completed, the fraction of patients experiencing the desired outcome is reported for the active and control groups.
The number needed to treat is derived from these values and indicates the magnitude of the therapy,s treatment effect on the disease that is observed in the clinical trial.
NNT is an important means to express the magnitude of benefit conf2242ed by in therapy.
The NNT is computed by dividing 100 by the difference between the percentage response of the treatment group from that of the control group.
It is calculated by taking the reciprocal of the absolute risk reduction, between the groups.
The NNT indicates how many patients must be managed on average with active rather than control therapy to achieve 1 additional good outcome.
The NNT may be applied to different outcomes from both therapeutic and diagnostic studies.
When therapy increases desirable outcomes, the resulting value is in is the number needed to benefit.
When a therapy increases adverse events, the resulting value is the number needed to harm.
When applied to diagnostic strategies: The resulting values of the number needed to screen for tests and asymptomatic individuals, and the number needed to diagnose for tests in symptomatic individuals.
P-values suggest statistical rather than clinical significance and in P-value there will be a difference in outcomes associated with the choice of therapy, but not how large the difference will be.
Similarly, risk ratios and odds ratios convey a relative rather than absolute difference in outcomes with different treatments.
The in NT conveys the absolute size of differences in outcome proportions with different treatments in an easily interpretable manner.