Improved confidence intervals for the sensitivity at a fixed level of specificity of a continuous-scale diagnostic test.

For a continuous-scale diagnostic test, it is of interest to construct a confidence interval for the sensitivity of the diagnostic test at the cut-off that yields a predetermined level of its specificity (for example, 80, 90 or 95 per cent). In this paper we propose two new intervals for the sensitivity of a continuous-scale diagnostic test at a fixed level of specificity. We then conduct simulation studies to compare the relative performance of these two intervals with the best existing BCa bootstrap interval, proposed by Platt et al. Our simulation results show that the newly proposed intervals are better than the BCa bootstrap interval in terms of coverage accuracy and interval length. Copyright 2005 John Wiley & Sons, Ltd.