Interrater reliability of the Wells score as part of the assessment of DVT in the emergency department: agreement between consultant and nurse practitioner

OBJECTIVES: To determine interobserver variability between an emergency medicine consultant and nurse practitioners for the use of the Wells score in the assessment of deep vein thrombosis (DVT) in the emergency department. METHODS: A prospective cohort study was undertaken in a population of 100 cases of suspected DVT. The Wells score reading from the consultant was compared with the reading of the nurse practitioners. Consultant and nurses were blinded to each other's assessments. The nurse practitioners were trained in interpreting the Wells score by assessing 100 patients together with the consultant before the start of the study. RESULTS: Consultant and nurse practitioner assessments resulted in the same final Wells score in 81% of cases (simple agreement), with a kappa score of 0.74 (95% CI 0.63 to 0.84). If the nurse practitioner score had been followed in preference to the consultant assessment, this would have resulted in eight patients being assessed in a lower risk algorithm (8%). CONCLUSION: There is good interobserver agreement between consultant and nurse practitioners for the use of the Wells score as part of a DVT assessment service within the emergency department. Pretest scoring is pivotal to integrated strategies for the exclusion of DVT. The Wells score is a robust and reliable tool for pretest scoring in the emergency department regardless of the grade of the assessor, provided there is adequate training in its use.