Clinical effects of antiplatelet drugs and statins on D-dimer levels

Background: Acute pulmonary embolism may be ruled out by combining nonhigh clinical probability and a normal D-dimer level. Both antiplatelet drugs and HMG-CoA reductase inhibitors (statins) have been associated with effects on thrombus formation, potentially influencing D-dimer levels in this setting, leading to a higher rate of false-negative tests. Therefore, we determined whether D-dimer levels in patients with suspected pulmonary embolism are affected by concomitant use of antiplatelet drugs and/or statins and evaluated whether the effect of antiplatelet drugs or statins might affect diagnostic accuracy.

Materials and methods: We performed a posthoc analysis in the YEARS diagnostic study, comparing age- and sex-adjusted D-dimer levels among users of antiplatelet drugs, statins and nonusers. We then reclassified patients within the YEARS algorithm by developing a model in which we adjusted D-dimer cut-offs for statin use and evaluated diagnostic accuracy.

Results: We included 156 statins users, 147 antiplatelet drugs users and 726 nonusers of either drugs, all with suspected pulmonary embolism. Use of antiplatelet drugs did not have a significant effect, whereas statin use was associated with 15% decrease in D-dimer levels (95% CI, -28% to -0.6%). An algorithm with lower D-dimer thresholds in statin users yielded lower specificity (0.42 compared to 0.33) with no difference in false-negative tests.

Conclusions: We conclude that use of statins but not of antiplatelet agents is associated with a modest decrease in D-dimer levels. Adjusting D-dimer cut-offs for statin use did, however, not result in a safer diagnostic strategy in our cohort.