Einschätzung des Behandlungseffektes durch die „Number needed to treat“

摘要

The amount of available information in medical literature has increased expeditiously. As more studies are performed, the results have become more easily accesible. More emphasis is now being put on effective use of biomedical literature to guide clinical treatment. As a result, accessing, critically appraising, and incorporating the results of clinical investigations into clinical practice are becoming higher priorities for doctors and medical students. A pivotal step in translating clinical research into practice is the summarisation of data from randomised trials in terms of measures of effect that can be readily appreciated by doctors and other carers. Various measures of the effect of treatment are used in analysing results. Randomised controlled trials are the gold standard in the assessment of a treatment effect. The magnitude of this effect can be presented in numerous ways, e. g. relative risk reduction (RRR) and odds ratio (OR). The number needed to treat (NNT)—first proposed by Laupacis and coworkers—is becoming increasingly popular as an index for reporting the results of randomised trials and other clinical studies. The NNT is the inverse of the absolute risk reduction resulting from a particular treatment in a particular group of patients. It should be noted that the NNT is generally expressed as a single number which is known as its point estimate. Therefore, a 95% confidence interval for the number needed to treat can be constructed simply by inverting and exchanging the limits of a 95% confidence interval for the absolute risk reduction. It is not appropriate to compare NNTs over disease conditions. Furthermore, an NNT is always based on an outcome for a specific period.