Gensini Gian Franco, Conti Andrea A
Department of Critical Care Medicine and Surgery, University of Florence, Don Carlo Gnocchi Foundation, Florence, Italian Center for Evidence-Based Medicine, Florence, Italy.
Ital Heart J. 2003 Feb;4(2):80-3.
The number needed to treat (NNT), calculated as the reciprocal of the absolute risk reduction, is a parameter that provides quantitative information on the efficacy of therapeutic interventions. The introduction of this parameter was provoked by the demonstration that physicians were not too familiar with the percentage expressions of risk reduction, but preferred, in assessing the efficacy of a treatment in the context of a clinical trial, numbers that directly indicated patients.
Although the results of the evolution in the concept of the NNT have been available for various years, the diffusion of such parameters is still poor. The frequency of explicit reporting of the NNT in the published randomized controlled trials of five major biomedical journals has been recently assessed. This review has shown that in 359 eligible papers, the NNT was recorded in only eight articles. This represents a major drawback of biomedical literature, since the NNT allows health operators to understand how much effort is needed to prevent a given event.
The NNT represents a measure of immediate and major clinical impact, and should always be reported, when appropriate, as an expression of the results of clinical trials. As a single number, it cannot stand alone as the sole justification for including a new treatment in the therapeutic armamentarium; still, it should be seen as an indicator by means of which the same treatment may be critically considered. It seems therefore appropriate to require that authors publishing results of clinical trials should provide readers with the information necessary to allow them to make responsible decisions; in this case, adopting the useful tool constituted by the NNT.
需治疗人数（NNT），计算为绝对风险降低率的倒数，是一个提供治疗干预疗效定量信息的参数。该参数的引入是因为有证据表明医生对风险降低的百分比表述不太熟悉，而在评估临床试验中一种治疗的疗效时，他们更喜欢直接表明患者情况的数字。
尽管NNT概念的演变结果已存在多年，但此类参数的传播情况仍然不佳。最近评估了五大生物医学期刊发表的随机对照试验中明确报告NNT的频率。该综述表明，在359篇符合条件的论文中，只有8篇文章记录了NNT。这是生物医学文献的一个主要缺陷，因为NNT能让医疗工作者了解预防特定事件需要付出多少努力。
NNT代表了直接且重大的临床影响指标，在适当的时候，作为临床试验结果的一种表述，应始终予以报告。作为一个单一数字，它不能单独作为将一种新治疗纳入治疗手段的唯一理由；不过它应被视为一个可据此对同一治疗进行批判性考量的指标。因此，要求发表临床试验结果的作者向读者提供必要信息，以便他们做出负责任的决定，在这种情况下，采用由NNT构成的有用工具，似乎是恰当的。
