Algorithms improve certainty in ruling out deep and pelvic vein thrombosis at the primary level of patient care, say Lobna El Tabei and her co-authors in the current issue of the Deutsches Ärzteblatt International.

Deep vein thrombosis (DVT) can lead to fatal pulmonary embolism or chronic post-thrombotic syndrome. To improve differential diagnostic certainty, scores have been developed that allow the clinical probability of DVT to be calculated on the basis of weighted combinations of individual clinical findings. Items of these scores are, for example, cancer, paresis of the leg, extended periods of bed rest, swelling, and pain.

The primary aim of the study was to determine diagnostic accuracy regarding exclusion of DVT using a treatment algorithm consisting of one of these scores, the Wells score, followed by either a D-dimer test and/or compression sonography -- depending on the result of the Wells score -- and to compare this with the diagnostic accuracy of the primary care physician's clinical judgment alone.

The algorithm investigated by the authors allows the primary care physician to rule out DVT with a high degree of probability. In this study, which included 395 patients, only 1% of cases of DVT were missed, compared with 5% when relying on clinical judgment alone.