Clinical question: Should the Wells score be used for DVT risk stratification in the hospital?
Background: The Wells score was derived to reduce lower extremity ultrasounds (LEUS) in the outpatient evaluation of DVTs. There has never been a large prospective trial to validate its use in hospitalized patients.
Study design: Single-center, prospective cohort study.
Setting: Quaternary care, academic hospital.
Synopsis: Between November 2012 and December 2013, all inpatients at a single medical center who underwent a LEUS for suspected DVT, including 1,135 inpatients 16 years or older, had Wells risk factors recorded. The incidence of proximal DVTs noted for low, moderate, and high pretest probability groups were 5.9%, 9.5%, and 16.4%, respectively. Compared to the outpatient incidence of 3.0%, 16.6%, and 74.6% reported by Wells and colleagues, there were nonsignificant differences among inpatient groups. The difference between low and moderate pretest probability groups was not significant.
Discrimination of risk for DVT in hospitalized patients performed only slightly better than chance (AUC, 0.60) and the failure rate was double that of the original outpatient study (5.9% vs. 3.0%).
A possible explanation for these findings is the increased prevalence of immobilization (6x), cancer (3x), and risk factors not included in the Wells score (COPD, heart failure, and infection) in hospitalized patients.
Bottom line: The Wells score may not be sufficient to rule out DVT or influence management in the inpatient setting.
Citation: Silveira PC, Ip IK, Goldhaber SZ, Piazza G, Benson CB, Khorasani R. Performance of Wells score for deep vein thrombosis in the inpatient setting. JAMA Intern Med. 2015;175(7):1112-1117.