Accuracy of diagnostic tests read with and without clinical information: a systematic review.

CONTEXT Although it is common practice to read tests with clinical information, whether this improves or decreases the accuracy of test reading is uncertain. OBJECTIVE To determine whether diagnostic tests are more accurate when read with clinical information or without it. DATA SOURCES MEDLINE search (1966-December 2003) extended by search of reference lists and articles citing the articles retrieved (Web of Science, 1985-December 2003). STUDY SELECTION All articles comparing the accuracy of tests read twice by the same readers, once without and once with clinical information, but otherwise under identical conditions. Only articles that reported sensitivity and specificity or receiver operating characteristic (ROC) curves were included. DATA EXTRACTION Data were extracted by one author and reviewed independently by the other. When the data were difficult to interpret, differences were resolved by discussion. DATA SYNTHESIS Sixteen articles met the inclusion criteria. Eleven articles compared areas under ROC curves for tests read with and without clinical information, and 5 compared only sensitivity and specificity. Ten articles used actual clinical information; 6 used constructed clinical information that was plausible. Overall, clinical information improved test reading accuracy although the effect was smaller in the articles using actual clinical information when compared with those using constructed clinical information. There were no instances in which clinical information resulted in significant reduction in test reading accuracy. In some instances, improved test reading accuracy came from improved sensitivity without loss of specificity. CONCLUSIONS At least for the tests examined, the common practice of reading diagnostic tests with clinical information seems justified. Future studies should be designed to investigate the best way of providing clinical information. These studies should also give an estimate of the accuracy of clinical information used, display ROC curves with identified data points, and include a wider range of diagnostic tests.