Turbidimetric D-dimer test in the diagnosis of pulmonary embolism: A metaanalysis

Background: Clinicians in outpatient clinics and emergency departments desire an accurate quantitative D-dimer assay. The study objective was to evaluate the diagnostic performance characteristics of the latex turbidimetric D-dimer test in the diagnosis of pulmonary embolism (PE) in the emergency department population. Methods: We conducted a search of MEDLINE, EMBASE, and bibliographies of previous systematic reviews with no language restriction. Experts in the field of PE research were contacted to identify unpublished studies. Prospective investigations involving predominately outpatient populations with suspected PE that used a turbidimetric D-dimer test were included. Two authors extracted data independently and assessed study quality based on the composition of the patient spectrum and the reference standard used. Consensus was reached by conference. The analysis was based on a summary ROC curve and combining sensitivity and specificity independently across studies using a random-effects model. Results: The search yielded 264 publications and 2 unpublished studies. Nine studies met the inclusion criteria and provided a sample of 1901 individuals. Eight of the nine studies were homogeneous in terms of both sensitivity and specificity. One study had similar sensitivity but higher specificity. Combining the studies yielded an overall sensitivity of 0.93 (95% confidence interval, 0.89-0.96) and an overall specificity of 0.51 (95% confidence interval, 0.42-0.59). Conclusions: The turbidimetric D-dimer test is sensitive but nonspecific for the detection of PE in the emergency department setting. D-Dimer tests using latex turbidimetric methods appear to have test characteristics comparable to those for ELISA methods. (C) 2003 American Association for Clinical Chemistry.