Author’s Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.
Dr. Worley is Instructor, Department of Emergency Medicine, NewYork-Presbyterian Hospital/Columbia University, New York, NY. Dr. Mattson is Resident, Department of Emergency Medicine, NewYork-Presbyterian Hospital, New York, NY. Dr. Bhatt is Assistant Professor, Department of Emergency Medicine, NewYork-Presbyterian Hospital/Columbia University, New York, NY.
There has been criticism from some European studies that the PERC rule misses too many PEs. A provocatively titled multinational study from Hugli et al examined patients suspected to have PE in Switzerland, France, and Belgium. The investigators applied the PERC rule and then stratified the patients by pretest probability as defined by the Geneva score, which includes many of the same criteria as PERC. They found the PERC rule identified a small proportion of patients with suspected PE as very low risk (13.2%) and that the prevalence of PE among these patients was 5.4%. Critics of this study have noted that the PERC rule was designed to be applied in low-risk patients, not to define the low-risk population.47 Another study examined a retrospective cohort of patients in whom a D-dimer was ordered to exclude PE, and then calculated the Wells’ and PERC score from the medical record. The investigators found that the combination of Wells and PERC missed 2 PEs out of their population of 377 patients.48 However, a subsequent meta-analysis analyzed 11 studies—including the two negative studies—and found a pooled sensitivity of 97%, specificity of 23%, and negative likelihood ratio of 0.18, concluding that when the pretest probability is low, PERC is sensitive enough to exclude D-dimer testing.49
Comment: Given the number of disease states and sampling techniques that can cause nonspecific elevation in D-dimer assay, the PERC rule provides a useful tool in low-risk populations for excluding PE without laboratory testing. The key is applying the rule to the appropriate population, as stratified by gestalt or clinical score.
Infectious Disease
Mortality in Emergency Department Sepsis (MEDS) score
The Mortality in Emergency Department Sepsis (MEDS) score was developed as a risk stratification tool for patients presenting to the ED with concern for sepsis. This score was prospectively derived from a population of 3301 ED patient encounters during which a blood culture was ordered. Charts were reviewed and several data points extracted and analyzed to determine the following univariate predictors of 28-day mortality: terminal illness, tachypnea or hypoxia, septic shock, platelets <150,000/mm3, bands >5%, age >65 years, lower respiratory infection, nursing home residence, and altered mental status. These predictors were assigned point values based on their odds ratios, and points are added to generate a total score. Mortality risk was stratified into groups based on total score, with percentage mortality as follows: score 0-4: 0.9%; 5-7: 2.0%; 8-12: 7.8%; 13-15: 20.2%; >15: 50%. A separate validation cohort had the following mortality rates: score 0-4: 1.1%; 5-7: 4.4%; 8-12: 9.3%; 13-15: 16.1%; >15: 39%.50
The MEDS score was subsequently shown to also be predictive for 1-year mortality as well, with an area under receiver operating curve (AUROC) of 0.76 for 1-year mortality.51 A subsequent study showed similar mortality rates when expanding the patient population to include all patients with systemic inflammatory response syndrome (SIRS), potentially broadening the potential application of MEDS in ED risk stratification.52 However, the score was shown to be less predictive in patients with severe sepsis and septic shock, underestimating mortality in all MEDS score groups.53 Still, the MEDS score was demonstrated in multiple validation studies as a reliable risk stratification tool in patients with suspected infection or SIRS.54,55
Comment: The MEDS score is not as well studied in the literature as the SIRS criteria or QuickSOFA but is a validated risk stratification tool in patients with suspected infection and is ED specific. This tool, similar to Pneumonia Severity Index and CURB-65 (discussed below), can guide management of patients from the ED. Very-low-risk (score 0-4) patients can be treated as outpatients, low risk (score 5-7) patients warranting consideration of a short inpatient stay, and moderate to high risk (>8) requiring inpatient management. At present, there is insufficient evidence regarding the role of the MEDS score to guide inpatient disposition of floor vs. ICU in moderate to high-risk patients.
