Intended for healthcare professionals

Endgames Statistical Question

Number needed to treat I

BMJ 2011; 342 doi: https://doi.org/10.1136/bmj.d2463 (Published 27 April 2011) Cite this as: BMJ 2011;342:d2463

An excellent example of the Rule 3-30 for clinical decision making

An excellent example of the Rule 3-30 for clinical decision making.

The study analyzed by Philip Sedgwick in this article on the Number
Needed to Treat (BMJ 27 April 2011) perfectly fits with the concept of the
Rule 3-30 that I published ten years ago (1).

After analyzing hundreds of trials, I recognized a pattern, which I
tested and confirmed to simplify the evaluation of the evidence. I called
this pattern: THE 3-30 RULE OF EVIDENCE BASED MEDICINE.[2].

Basically it means that the trials that are clinically significant
and/or cost- effective fulfill at least two of the following
characteristics: a Relative Risk Reduction of 30% or more (not less than
20%), an Absolute Risk Reduction of 3% or more (not less than 2%), and a
Number Needed to Treat or NNT of 30 or less (not more than 50), that is,
for every 30 patients that we treat, compared with controls, we save a
life or avoid one clinical event.

This simple rule rapidly identifies the Randomized Clinical Trials
(R.C.T.) that could have practical clinical applications. The following is
a partial list of very successful and well known R.C.T. that clearly
fulfill THE 3-30 RULE OF EVIDENCE BASED MEDICINE: ISIS-2, RALES, 4S,
LIPID, CARE, WOSCOPS, AFCAPS/TexCAPS, CURE and ASSENT-3, among many others
since then.

Prof. Enrique Sanchez-Delgado, M.D.

1.- A C Freeman and K Sweeney. Why general practitioners do not
implement evidence: qualitative study. BMJ 2001; 323: 1100 (10 November).

2.- E Sanchez-Delgado. Evidence Based Medicine: Rule
3-30. Presented at the XXXII National Medical Congress of the Nicaraguan
Medical Association. Managua 08 September 2001.

Competing interests: No competing interests

02 May 2011
Enrique J. Sanchez Delgado
Internal Medicine-Clinical Pharmacology. Director of Medical Education
Hospital Metropolitano Vivian Pellas, Managua, NIcaragua