The Numbers Needed to Treat and Harm (NNT, NNH) Statistics: What They Tell Us and What They Do Not

Understanding Relative Risk, Odds Ratio, and Related Terms: As Simple as It Can Get

“…It is possible for an RR value to be well below 1.00, or well above 1.00, and yet not statistically significant, and it is possible for an RR value to be very close to 1.00 (ie, probably not clinically significant) but yet statistically significant because the study was conducted on a large sample. 6. RR values are accompanied by their 95% confidence intervals (CIs).…”

Risk of Major Congenital Malformations Associated With the Use of Methylphenidate or Amphetamines in Pregnancy

“…This translates to a number needed to harm of 278, 24 indicating that the clinical significance of the finding is very small.…”

Likelihood of Being Helped or Harmed as a Measure of Clinical Outcomes in Psychopharmacology

“…In this regard, the LHH is no better or worse than the NNT and NNH. 2,3 As already stated, different statistics serve different purposes, and each has its own value.…”

“…Previous articles in this column addressed certain of these measures of effect size and related subjects. [1][2][3][4] The present article considers the LHH.…”