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theNNT, Explained

There is a way of understanding how much modern medicine has to offer individual patients. It is a simple statistical concept called the “Number-Needed-to-Treat”, or for short the ‘NNT’. The NNT offers a measurement of the impact of a medicine or therapy by estimating the number of patients that need to be treated in order to have an impact on one person. The concept is statistical, but intuitive, for we know that not everyone is helped by a medicine or intervention — some benefit, some are harmed, and some are unaffected. The NNT tells us how many of each.

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We are a group of physicians that have developed a framework and rating system to evaluate therapies based on their patient-important benefits and harms as well as a system to evaluate diagnostics by patient sign, symptom, lab test or study. We only use the highest quality, evidence-based studies (frequently, but not always Cochrane Reviews), and we accept no outside funding or advertisements.

Articles of Interest

Calculating and using NNTs

Not everyone is comfortable with calculating and using numbers needed to treat (NNTs). Surveys of GPs, for instance [1], suggest that perhaps under half are confident with them. That means that more than half are not. Some form of aide memoir should be helpful, and this essay includes worked examples and an NNT worksheet that can be copied and used for clinical trials and systematic reviews.

Availability and use of number needed to treat (NNT) based decision aids for pharmaceutical interventions

The number needed to treat (NNT) is a medical statistic used to gauge the efficacy of therapeutic interventions. The versatility of this absolute effect measure has allowed its use in the formulation of many decision aids to support patients and practitioners in making informed healthcare choices.

Compelling or irrelevant? Using number needed to treat can help decide

NNT is an effect size and independent of statistical significance, and thus is best used together with its confidence interval. The quality of the NNT estimate is highly dependent on the quality of the source data. Poorly designed and badly analyzed studies yield NNTs of questionable utility.

How effective is that treatment? The number needed to treat

The Number Needed to Treat (NNT) is a tool useful for comparing the relative effectiveness of two or more therapeutic or preventive interventions. The NNT may be presented by authors of a clinical research article, or, if not provided, may be calculated by the reader if the authors have reported outcomes as positive or negative per research subject.

Number Needed to Treat (NNT)

The Number Needed to Treat (NNT) is the number of patients you need to treat to prevent one additional bad outcome (death, stroke, etc.).

Number Needed to Treat (NNT)

The Number Needed to Treat (NNT) is the number of patients you need to treat to prevent one additional bad outcome (death, stroke, etc.).

Number needed to treat (NNT) in clinical literature: an appraisal

The number needed to treat (NNT) is an absolute effect measure that has been used to assess beneficial and harmful effects of medical interventions. Several methods can be used to calculate NNTs, and they should be applied depending on the different study characteristics, such as the design and type of variable used to measure outcomes.

Number needed to treat (NNT) in clinical literature: an appraisal

The concept of ”number needed to treat” (NNT) was introduced in the medical literature by Laupacis et al. in 1988 [1]. NNT is an absolute effect measure which is interpreted as the number of patients needed to be treated with one therapy versus another for one patient to encounter an additional outcome of interest within a defined period of time.

Number Needed to Treat: What It Is and What It Isn’ t, and Why Every Clinician Should Know How to Calculate It

Of all the measures of effect size, NNT is perhaps the easiest to calculate and is likely the most clinically intuitive. It answers the question: How many patients do I need to treat with treatment A vs treatment B before I would expect to encounter 1 additional outcome of interest, such as response?

Numbers needed to treat (NNTs) - calculation, interpretation, advantages and disadvantages

First described in 19881, the number needed to treat (NNT) can be thought of as the number of patients that need to be treated in order for one to benefit. It provides an attractive means of summarising the results of a clinical trial in a single figure, because the meaning of a sentence such as ‘20 patients need to be treated to avoid one additional death over a five-year period’ is easily understood by both doctors and patients.

Resources

NNT Calculator

The idea of NNT provides clinicians with a method of explaining the relative benefit or harm of a given therapy for a patient. Because of its simplicity, NNT has the following weaknesses:..