We thank Dr. Schwartz for his letter about our recent article. He raised the concern that pulmonary embolism rule-out criteria (PERC) were not defined consistently among the studies, which may have affected the calculated sensitivities and suitability of pooled results. Special concern was raised about the study by Hugli et al, from which all patients (low, medium, and high risk) were included in the meta-analysis. We agree that PERC was designed to be used in a low-risk population; however, even after excluding the moderate- and high-risk patients from the study by Hugli et al, overall sensitivity decreased minimally (from 97% to 96%), but the heterogeneity increased significantly (I2=71%; P<.001). On sensitivity analysis, after excluding the study by Hugli et al from the meta-analysis, pooled sensitivity (97%) was similar to that of our original study, with no significant heterogeneity (I2=24%, P=.26) observed between the studies. Similar results were found after we excluded the study by Hugli et al from another meta-analysis with a larger number of patients (sensitivity 0.97%; I2=30.7%; P=.15).
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