Number Needed to Treat (NNT)
The number of patients who need to receive a treatment for one additional patient to benefit compared to control. A measure of clinical significance.
In Depth
NNT is calculated as 1/absolute risk reduction. Lower NNT indicates more effective treatment. For cannabis in chronic pain, NNT values of 5–10 have been reported (meaning 5–10 patients need treatment for one to achieve meaningful pain relief). For CBD in Dravet syndrome, NNT is approximately 8 for 50% seizure reduction. NNT should be interpreted alongside NNH (number needed to harm) to assess the benefit-risk ratio of cannabinoid therapy.
Related Terms
More in Research Methods
Randomized Controlled Trial (RCT)
The gold standard study design in clinical research. Participants are randomly assigned to treatment or control groups to minimize bias and establish causation.
Systematic Review
A structured synthesis of all available evidence on a specific research question, using predefined criteria to identify, evaluate, and summarize studies.
Meta-Analysis
A statistical technique that combines quantitative data from multiple studies to produce a pooled estimate of effect size with greater statistical power than any individual study.
Placebo-Controlled
A study design in which the control group receives an inert substance (placebo) identical in appearance to the active treatment, to account for the placebo effect.
Observational Study
A study in which researchers observe participants without intervening. Includes cohort studies, case-control studies, and cross-sectional surveys.