Diagnostic tests are more accurate than estimates suggest

05/07/04

Tests to diagnose endometrial hyperplasia, a condition where the uterus lining becomes overgrown, are more accurate than experiments have suggested. A study published this week in BMC Medicine shows that delays in verifying test results have led to underestimates of test accuracy.

Researchers from Birmingham Women's Hospital systematically reviewed all the published research on the accuracy of diagnostic tests for endometrial hyperplasia. They found that if researchers waited more than 24 hours to check test results, the accuracy of the original test was underestimated.

The researchers believe that, "to obtain accurate estimates of test accuracy in studies of hyperplasia, an immediate comparison of the test under scrutiny with a reference standard that verifies the diagnosis will be essential."

Endometrial hyperplasia is a benign condition that can lead to irregular or excessive vaginal bleeding. In most cases it is treatable with hormone therapy.

The condition is diagnosed by measuring the thickness of the uterus wall using ultrasound, or via a miniature biopsy of endometrial tissue. To test how accurate the diagnoses are a second sample of the uterus lining is taken, slides are made and assessed, and these results are compared to the original test results.

The researchers looked at 27 primary studies. In 16 of these, test results were checked within 24 hours. In three of the other 11, lab staff checked the test results within a week; in one, they waited up to six months to verify results. The researchers measured the effect of these delays on the apparent accuracy of the initial tests.

"The underestimation of test accuracy among studies with delayed verification was 74% on average compared to studies with immediate verification."

The group, led by Justin Clark, also assessed the quality of the published studies and found that in general the studies were poorly designed. For example, in many studies when lab staff were analysing slides to confirm test results, they were already aware of the outcome of the initial tests. This knowledge could well have biased their conclusions.

The researchers believe that, "poor study designs may reflect the situation prevalent in routine clinical practice where test results may not be immediately confirmed due to resource and other implications. Thus diagnostic evaluations carried out in routine practice may mask the accuracy of tests."

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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