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.