What is NNTB?

Another method for presenting non-significant NNTs is to use the concepts of “number needed to treat in order to benefit one person” (NNTB) and the “number needed to treat in order to harm one person” (NNTH).

How do you calculate NNH?

From this the value known as the number needed to harm (NNH) can be calculated by dividing 1 by the absolute risk increase, and again multiplying by 100 when the ARI is expressed as a percentage. NNH shows how many individuals would need to be treated with the drug in order for 1 to show the harmful effect.

How is NTT calculated?

NNTs are always rounded up to the nearest whole number and accompanied as standard by the 95% confidence interval. Example: if a drug reduces the risk of a bad outcome from 50% to 40%, the ARR = 0.5 – 0.4 = 0.1. Therefore, the NNT = 1/ARR = 10. The ideal NNT would be 1 – ie all patients treated will benefit.

What is a good NNT value?

As a general rule of thumb, an NNT of 5 or under for treating a symptomatic condition is usually considered to be acceptable and in some cases even NNTs below 10. Below are some NNTs for routine medical interventions.

What does a negative NNH mean?

A negative NNH means that a patient assigned to the comparator (placebo) has a lower risk for the adverse event of interest than a patient assigned to the medication under study.

What is the difference between absolute and relative risk reduction?

The relative risk reduction is the difference in event rates between two groups, expressed as a proportion of the event rate in the untreated group. The absolute risk reduction is the arithmetic difference between the event rates in the two groups.

What is a high NNH?

An ideal new drug or treatment would have a low NNT and a high NNH because this means that only a few people need to be treated for a benefit to occur while a lot of people need to be treated for something harmful to occur.

What is a bad NNH?

This is calculated in the same way as for NNT, but used to describe adverse events. For NNH, large numbers are good, because they mean that adverse events are rare. Small values for NNH are bad, because they mean adverse events are common.

What is a significant number needed to treat?

The number needed to treat is an aggregate measure of clinical benefit that represents the number of patients who would need to be treated to prevent 1 additional adverse event. It is calculated by taking the reciprocal of the absolute risk reduction between 2 treatment options.

What does a high NNH mean?

Number Needed to Harm
Number Needed to Harm (NNH) is a measure of how many people need to be treated (or exposed to a risk factor) in order for one person to have a particular adverse effect. The lower the NNH, the more risk of harm; An NNH of 1 would mean that every patient treated is harmed.

What is absolute risk reduction in statistics?

Absolute risk reduction (also called risk difference) is the absolute difference in outcomes between one group (usually the control group) and the group receiving treatment. The percentage tells you how much the risk of something happening decreases if a certain intervention happens.

How do you explain absolute risk reduction?

Absolute risk is the size of your own risk. Absolute risk reduction is the number of percentage points your own risk goes down if you do something protective, such as stop drinking alcohol. The size of your absolute risk reduction depends on what your risk is to begin with.

Which is the most commonly quoted NNT statistic?

The most commonly quoted NNT statistic is NNT [risk difference] or the empirical NNT, which assumes a constant risk difference over different expected event rates. The other NNT statistics assume that a relative measure (RRe, RRne or OR) is constant over different expected event rates, therefore these NNTs vary with the expected event rate.

How is the number needed to be exposed ( NNT ) used?

Furthermore, “number needed to be exposed” (NNE) has been proposed to apply the concept of NNT in observational studies, in which the focus is exposure rather than treatment [ 22 ]. NNEB and NNEH can be used to describe the number needed to be exposed for one person to benefit or be harmed [ 22 ].

Why is the number needed to treat ( NNT ) important?

In addition, three other factors, beyond the efficacy or safety of the intervention and the comparator, influence NNT: baseline risk (i.e., control event rate [CER]), time frame, and outcomes [ 3 ]. The use of NNT has been valuable in daily clinical practice, namely at assisting physicians in selecting therapeutic interventions [ 4, 5 ].

How are NNTs calculated in the medical literature?

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. Whether or not the most recommended methods have been applied to calculate NNTs in studies published in the medical literature is yet to be determined.