Reporting of D-dimer Testing in Venous Thromboembolism Diagnostic Management Studies: A Scoping Review.

Background D-dimer testing is widely integrated into diagnostic algorithms for venous thromboembolism (VTE). However, the lack of standardization across D-dimer assays and reporting may limit comparability of study findings. Objective To summarize reporting of essential characteristics of D-dimer testing in VTE diagnostic management studies. Methods We systematically searched MEDLINE and Embase from 01/1999-08/2024 for VTE diagnostic management studies that evaluated diagnostic algorithms including D-dimer testing and followed patients for ≥4 weeks after VTE was excluded. The primary outcome was reporting of D-dimer assay characteristics. Secondary outcomes were reporting of patient numbers and failure rates per assay. Results Of 9,670 articles screened, 58 studies were included: 36 (62%) enrolled patients with suspected pulmonary embolism, 21 (36%) with suspected deep vein thrombosis, and one with suspected VTE. Sample sizes ranged from 191-5,400; follow-up was 1-6 months. Assay name was fully reported in 52/58 (90%), manufacturer in 49/58 (85%), unit magnitude in 42/46 (91%), and unit type in 8/46 (17%) studies. Detection limit was reported in 3/58 (5.2%) studies; other analytical performance parameters were unreported. Nineteen quantitative assays were used across 19 combinations of thresholds and unit magnitudes. Of 17 studies using multiple assays, 9 reported patient numbers per assay and one reported failure rates per assay. Conclusion Key characteristics of D-dimer testing were inconsistently reported in VTE diagnostic management studies. While assay name, manufacturer, unit magnitude, and thresholds were often included, unit type and assay-specific data were frequently omitted. Minimum reporting standards for D-dimer testing are needed for VTE diagnostic management studies.