Background/Aims: Clinical prediction rules form an integral component of guidelines on the diagnostic approach to pulmonary embolism (PE). The Wells Score is commonly used but is subjective, while the newer Revised Geneva Score is based entirely on objective variables. The aim of this study was to compare the diagnostic accuracy of the Wells and Revised Geneva Scores for the diagnosis of PE.
Methods: Patients presenting to the emergency department with clinically suspected PE and referred for CT pulmonary angiogram or ventilation/perfusion scintigraphy were evaluated. The Wells and Revised Geneva Scores were calculated on the same cohort of patients and dichotomized into low and intermediate/high probability groups. The sensitivities and specificities were compared using McNemar's test. Overall accuracy was determined using receiver operator characteristic curve analysis.
Results: A total of 98 consecutive patients was included. The overall prevalence of PE was 15.3%. The frequency of PE in the low, intermediate and high probability groups was similar for both clinical prediction rules. Compared with the Revised Geneva Score, the Wells Score showed a lower sensitivity with borderline significance (46.7% vs 80.0%, P= 0.06) and a significantly higher specificity (67.5% vs 47.0%, P= 0.002). The overall accuracy of both rules was similar (P= 0.617).
Conclusion: Using the accepted guidelines in which a high pretest probability leads to further imaging and a low probability leads to a D-dimer blood test, use of the more specific Wells Score could safely reduce the number of unnecessary scans. This would need to be confirmed with larger, prospective trials.