D-dimer Levels for the Exclusion of Pulmonary Embolism: Making Sense of International Guideline Recommendations

Several international guidelines provide recommendations around the use of D-dimer testing for exclusion of pulmonary embolism (PE), including the appropriate D-dimer threshold (or cutoff), but there is no consensus amongst them. We briefly discuss guideline variation, performance characteristics and limitations of commercially available D-dimer assays in this setting, referencing the Clinical and Laboratory Standards Institute (CLSI) guidelines that recommend immunoassays with high sensitivity (≥97%) and negative predictive value (≥98%). While age-adjusted D-dimer and pre-test adjusted D-dimer is considered a safe strategy across predefined patient subgroups, clinicians need to recognise the different performance characteristics of D-dimer assays, to enable safe clinical decisions for their patients. Importantly, D-dimer values must be correlated not only to clinical findings, but also interpreted within the context of the accuracy and precision of the specific testing modality, adhering to manufacturer specifications that are approved by regulatory authorities.