Effects of adjustment for referral bias on the sensitivity and specificity of single photon emission computed tomography for the diagnosis of XXXX .

@entity1 @entity453 @entity301
PURPOSE: Referral bias, in which the result of a diagnostic test affects the subsequent referral for a more definitive test, influences the accuracy of noninvasive tests for @entity453 . This study evaluates the effect of referral bias on the apparent accuracy of single photon emission computed tomography (SPECT). METHODS: Over a 10-year period, 14,273 @entity1 without known @entity453 underwent stress SPECT. Coronary angiography was performed within 3 months after the stress test in 1853 @entity1 (13%). The apparent sensitivity, specificity, and likelihood ratios of SPECT were determined in these @entity1 , and then adjusted for referral bias using two different formulas. RESULTS: The overwhelming majority (95%) of @entity1 who underwent angiography had abnormal SPECT images. Apparent values for test indices were a sensitivity of 98%, a specificity of 13%, a likelihood ratio for a positive test of 1.1, and a likelihood ratio for a negative test of 0.15. Test indices adjusted for referral bias (using the two methods) were a sensitivity of 65% or 67%, a specificity of 67% or 75%, a likelihood ratio for a positive test of 2.0 or 2.7, and a likelihood ratio for a negative test of 0.44 or 0.52. CONCLUSION: Referral bias has a marked effect on the apparent accuracy of stress SPECT for the diagnosis of @entity301 . Adjustment for referral bias yields estimates for sensitivity and specificity and likelihood ratios that better reflect the accuracy of the technique.
