ITEM 12. Describe methods for calculating or comparing measures of diagnostic accuracy, and the statistical methods used to quantify uncertainty (e.g. 95% confidence intervals)
The statistical significance of the differences in sensitivities between magnetic resonance angiography (MRA) and duplex were assessed by means of the McNemar test.
Several measures of diagnostic accuracy exist. Authors should report in sufficient detail the methods used in calculating the measures that they considered appropriate. Estimates of diagnostic accuracy are subject to chance variation, with larger studies usually resulting in more precise estimates. Authors should therefore quantify the amount of statistical uncertainty around the observed value. Articles that describe methods for calculating the precision around frequently used measures of diagnostic accuracy are readily available.
Alternatively, statistical techniques can be used to test more specific hypotheses, such as the superiority of one test over another, or the hypothesis that a specific measure of diagnostic accuracy surpasses a pre-specified value.
In the example, the authors used McNemar test statistic to reject the null hypothesis that magnetic resonance angiography had the same sensitivity as duplex sonography for diagnosing renovascular disease.
Leung DA, Hoffmann U, Pfammatter T, et al. Magnetic resonance angiography versus duplex sonography for diagnosing renovascular disease. Hypertension 1999; 33:726-31.
Habbema JDF, Eijkemans R, Krijnen P, Knottnerus JA. Analysis of data on the accuracy of diagnostic tests. In: Knottnerus JA, ed. The evidence base of clinical diagnosis. London: BMJ Publishing Group, 2002:117-44.
Lang TA, Secic M. Generalizing from a sample to a population: Reporting estimates and confidence intervals. In: Lang TA, Secic M, eds. How to report statistics in medicine: Annotated guidelines for authors, editors, and reviewers. Philadelphia: American College of Physicians, 1997:55-63.