Wells score, negative D-dimer test can rule out pulmonary embolism in primary care

A Wells score of 4 or lower and a negative qualitative D-dimer test result can safely and efficiently exclude pulmonary embolism in primary care, a study found.

Researchers conducted a prospective cohort study among 300 primary care doctors in the Netherlands, providing them with study forms and written instruction on how to use the D-dimer test from July 2007 to December 2010.

Results appeared in the Oct. 9 BMJ.

There were 598 patients considered, with a mean age of 48 years, 71% of whom were women.

Venous thromboembolism was present in 73 patients (12.2%), with 68 cases of pulmonary embolism diagnosed immediately after referral. Four additional cases of pulmonary embolism and one deep venous thrombosis were found during three months of follow-up.

Overall, 422 patients had a Wells score of 4 or less and 237 had a score of less than 2. Venous thromboembolism was present in 21 (5%; 95% CI, 3.1% to 7.5%) and 7 (3%; 95% CI, 1.2% to 6%) of these patients, respectively. Venous thromboembolism occurred in 52 patients with a Wells score of greater than 4 (29.5%; 95% CI, 22.9% to 36.9%).

In total, 272 of the patients had both a Wells score of 4 or lower and a negative D-dimer test result, and only four of them were diagnosed with pulmonary embolism, a failure rate of 1.5% (95% CI, 0.4% to 3.7%). A failure rate of less than 2% is considered safe by most consensus statements, researchers noted. The combination of Wells score and D-dimer had a sensitivity of 94.5% and a specificity of 51%.

“Such a rule-out strategy makes it possible for primary care doctors to safely exclude pulmonary embolism in a large proportion of patients suspected of having the condition, thereby reducing the costs and burden to the patient (for example, reducing the risk of contrast nephropathy associated with spiral computed tomography) associated with an unnecessary referral to secondary care,” the researchers concluded.