Meta-analysis of usefulness of d-dimer to diagnose acute aortic dissection

Numerous studies have examined whether plasma D-dimer (DD) can be used to identify patients with acute aortic dissection (AAD). These studies have been inconclusive because of their limited sample sizes and the different cut-off values employed. We aimed to conduct a systematic review and meta-analysis to examine the utility of plasma DD as a screening tool for AAD. We systematically searched EMBASE and MEDLINE and hand-searched relevant articles to identify studies investigating plasma DD as a screening tool for AAD. A value of 500 ng/ml was defined as the threshold for a positive plasma DD finding because it is widely used for ruling out pulmonary emboli. Using DerSimonian-Laird random-effects models we pooled data across studies to estimate sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios (LRs). We identified 7 studies involving 298 subjects with AAD and 436 without. When data were pooled across studies, sensitivity (0.97, 95% confidence interval [CI] 0.94 to 0.99) and negative predictive value (0.96, 95% CI 0.93 to 0.98) were high. Specificity (0.56, 95% CI 0.51 to 0.60) and positive predictive value (0.60, 95% CI 0.55 to 0.66) were low. Negative LR showed an excellent discriminative ability (0.06, 95% CI 0.03 to 0.12), whereas positive LR did not (2.43, 95% CI 1.89 to 3.12). In conclusion, our meta-analysis suggests that plasma DD <500 ng/ml is a useful screening tool to identify patients who do not have AAD. Plasma DD may thus be used to identify subjects who are unlikely to benefit from further aortic imaging.