ITEM 21.  Report estimates of diagnostic accuracy and measures of statistical uncertainty (e.g.95% confidence intervals).

 

 

Example

ROC plots comparing CDTect values with %CDT values for men and women independently are given in Fig. 2. (…) The areas under the curves (with 95% confidence intervals) were 0.88 (0.85–0.91) and 0.89 (0.86–0.92) for men (P = 0.67) and 0.72 (0.68–0.76) and 0.76 (0.72–0.81) for women (P = 0.26), respectively.[1]

The final aim of a study of diagnostic accuracy is to produce an expression of how well the test results corresponded with the presence or absence of the target condition, as established by the reference standard. The values presented in the report should be taken as estimates. Due to chance variations in the patients submitted to the tests and other factors, the results are likely to differ over replications of the study in the same study population.[2] The reporting of precision will show the reader the range of likely values around an estimate of diagnostic accuracy.

Many journals require or strongly encourage the use of confidence intervals as measures of precision. A 95% confidence interval is conventional. Only 50% of the reports of diagnostic evaluations published in 1996 or 1997 in the British Medical Journal reported precision for the estimates of diagnostic accuracy.[3]

 

References

1. Anton RF, Dominick C, Bigelow M, Westby C. Comparison of Bio-Rad %CDT TIA and CDTect as laboratory markers of heavy alcohol use and their relationships with gamma-glutamyltransferase. Clin Chem 2001; 47:1769-75.
2. 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.
3. Harper R, Reeves B. Reporting of precision of estimates for diagnostic accuracy: a review. BMJ 1999;318:1322-3.