Validity and clinical utility of the simplified Wells rule for assessing clinical probability for the exclusion of pulmonary embolism

Summary

The recently introduced simplified Wells rule for the exclusion of pulmonary embolism (PE) assigns only one point to the seven variables of the original Wells rule. This study was performed to independently validate the simplified Wells rule for the exclusion of PE. We retrospectively calculated the prevalence of PE in the “unlikely” probability categories of the original Wells (cut-off ≤4) and the simplified Wells rule (cut-off ≤1) in 922 consecutive patients with clinically suspected PE from a multicenter cohort study. We compared the three-month incidence of venous thromboembolism (VTE) in patients with an unlikely probability and a normal D-dimer test using both scores, and the proportion of patients with this combination (clinical utility). The proportion of patients categorized as PE “unlikely” was similar using the original (78%) and the simplified (70%) Wells rule. The prevalence of PE was 13% (95% confidence interval [CI], 11–16%) and 12% (95%CI, 9.7–15%) for the original Wells and simplified Wells “unlikely” categories, respectively. None of the patients with PE “unlikely” and a normal D-dimer test experienced VTE during three-month follow-up. The proportions of patients in whom further tests could safely be withheld based on PE “unlikely” and a normal D-dimer test was 28% (95%CI, 25–31%) using the original and 26% (95%CI, 24–29%) using the simplified Wells rule. In this external retrospective validation study, the simplified Wells rule appeared to be safe and clinically useful, although prospective validation remains necessary. Simplification of the Wells rule may enhance the applicability.

Keywords

Pulmonary embolism - diagnosis - clinical decision rule - Wells rule - D-dimer

• References

• 1 Kline JA, Nelson RD, Jackson RE. et al. Criteria for the safe use of D-dimer testing in emergency department patients with suspected pulmonary embolism: a multicenter US study. Ann Emerg Med 2002; 39: 144-152.
• 2 Miniati M, Prediletto R, Formichi B. et al. Accuracy of clinical assessment in the diagnosis of pulmonary embolism. Am J Respir Crit Care Med 1999; 159: 864-871.
• 3 Wicki J, Perneger TV, Junod AF. et al. Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score. Arch Intern Med 2001; 161: 92-97.
• 4 Wells PS, Anderson DR, Rodger M. et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer. Thromb Haemost 2000; 83: 416-420.
• 5 Le Gal G, Righini M, Roy PM. et al. Prediction of pulmonary embolism in the emergency department: the revised Geneva score. Ann Intern Med 2006; 144: 165-171.
• 6 Wells PS, Anderson DR, Rodger M. et al. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer. Ann Intern Med 2001; 135: 98-107.
• 7 van Belle A, Buller HR, Huisman MV. et al. Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. J Am Med Assoc 2006; 295: 172-179.
• 8 Ten Cate-Hoek AJ, Prins MH. Management studies using a combination of D-dimer test result and clinical probability to rule out venous thromboembolism: a systematic review. J Thromb Haemost 2005; 03: 2465-2470.
• 9 Perrier A, Roy PM, Sanchez O. et al. Multidetectorrow computed tomography in suspected pulmonary embolism. N Engl J Med 2005; 352: 1760-1768.
• 10 Goekoop RJ, Steeghs N, Niessen RW. et al. Simple and safe exclusion of pulmonary embolism in outpatients using quantitative D-dimer and Wells’ simplified decision rule. Thromb Haemost 2007; 97: 146-150.
• 11 Qaseem A, Snow V, Barry P. et al. Current diagnosis of venous thromboembolism in primary care: a clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Fam Med 2007; 05: 57-62.
• 12 British Thoracic Society guidelines for the management of suspected acute pulmonary embolism. Thorax 2003; 58: 470-483.
• 13 Gibson NS, Sohne M, Kruip MJ. et al. Further validation and simplification of the Wells clinical decision rule in pulmonary embolism. Thromb Haemost 2008; 99: 229-234.
• 14 Perrier A, Roy PM, Aujesky D. et al. Diagnosing pulmonary embolism in outpatients with clinical assessment, D-dimer measurement, venous ultrasound, and helical computed tomography: a multicenter management study. Am J Med 2004; 116: 291-299.
• 15 McGinn TG, Guyatt GH, Wyer PC. et al. Users’ guides to the medical literature: XXII: how to use articles about clinical decision rules. Evidence-Based Medicine Working Group. J Am Med Assoc 2000; 284: 79-84.
• 16 Kelly J, Hunt BJ. A clinical probability assessment and D-dimer measurement should be the initial step in the investigation of suspected venous thromboembolism. Chest 2003; 124: 1116-1119.
• 17 Ginsberg JS, Wells PS, Kearon C. et al. Sensitivity and specificity of a rapid whole-blood assay for D-dimer in the diagnosis of pulmonary embolism. Ann Intern Med 1998; 129: 1006-1011.
• 18 Di Nisio M, Squizzato A, Rutjes AW. et al. Diagnostic accuracy of D-dimer test for exclusion of venous thromboembolism: a systematic review. J Thromb Haemost 2007; 05: 296-304.
• 19 Gibson NS, Sohne M, Gerdes VE. et al. The importance of clinical probability assessment in interpreting a normal D-dimer in patients with suspected pulmonary embolism. Chest. 2008 in press.