Making Sure Our Dead Are Dead: A Diagnostic Test Accuracy Meta-Analysis On Using Transcranial Doppler For Brain Death

BACKGROUNDBrain death in most countries requires supplementation of clinical diagnosis with ancillary tests such as EEG, cerebral angiography, or radionuclide imaging. Transcranial Doppler sonography (TCD) is one such non-invasive, real-time, bedside test that sidesteps the logistic hurdles associated with some of the tests mentioned above. OBJECTIVETo substantiate the utility of TCD as a reliable ancillary test to diagnose brain death with more certainty and reliability.METHODOLOGYMeta-analysis was performed with the use of statistical and analytical software to obtain data and estimate Sensitivity, Specificity, positive predictive value(PPV), diagnostic odds ratio (DOR), and relative risk with 95 percent confidence intervals to examine critical clinical outcomes(CI).RESULTSInitial dataset of 31 studies of which 16 studies, with a total of 1317 patients was used considering the reliability of the data. The pooled sensitivity and specificity of TCD were 0.91 (95% CI range: 0.89-0.93) and 0.99 (95% CI range: 0.97-0.99) respectively. The summary of the ROC curve showed an area under the curve of 0.9750 and an overall diagnostic odds ratio (DOR) was 323.26 with the Younden Index being 0.9. Summary of Fagan plot analysis of all studies showed a prior probability of 63% (1.7); a Positive Likelihood Ratio of 56, a post-test probability of 99% (96); a Negative likelihood ratio of 0.09, and a post-test probability of 13% (0.2).CONCLUSIONOur study emphasizes that clinical diagnosis is sufficiently adequate to declare a patient cerebrally dead. However, for ambiguous cases, TCD is a practical and fast method showing close correspondence to angiography and is superior to other bedside tests like EEG.