Comparing the diagnostic performance of 2 clinical decision rules to rule out deep vein thrombosis in primary care patients.

PURPOSE: The Wells rule is widely used for clinical assessment of patients with suspected deep vein thrombosis (DVT), especially in the secondary care setting. Recently a new clinical decision rule for primary care patients (the primary care rule) has been proposed, because the Wells rule is not sufficient to rule out DVT in this setting. The objective was to compare the ability of both rules to safely rule out DVT and to efficiently reduce the number of referrals for leg ultrasound investigation that would result in a negative finding. METHODS: Family physicians collected data on 1,086 patients to calculate the scores for both decision rules before leg ultrasonography was performed. In all patients D-dimer (dimerized plasmin fragment D) testing was performed using a rapid point-of-care assay. Patients were stratified into risk categories defined by each rule and the D-dimer result. Outcomes were DVT (diagnosed by ultrasonography) and venous thromboembolic complications or death caused by a possible thromboembolic event during a 90-day follow-up period. We calculated the differences between the 2 rules in the number of missed diagnoses and the proportions of patients that needed ultrasound testing. RESULTS: Data from 1,002 eligible patients were used for this analysis. A venous thromboembolic event occurred during follow-up in 7 patients with a low score and negative D-dimer finding, both with the Wells rule (7 of 447; 1.6%; 95% confidence interval [CI], 0.7%-3.3% ) and the primary care rule (7 of 495; 1.4%; 95% CI, 0.6%-3.0%). Using the Wells rule, 447 patients (45%) would not need referral for further testing compared with 495 patients (49%) when using the primary care rule (McNemar P <.001). CONCLUSIONS: In primary care, suspected DVT can safely be ruled out using either of the 2 rules in combination with a point-of-care D-dimer test. Both rules can reduce unnecessary referrals for compression ultrasonography by about 50%, though the primary care rule reduces it slightly more.

Idiopathic superficial thrombophlebitis and the incidence of cancer in primary care patients.

PURPOSE: The association of spontaneous venous thromboembolism with occult malignancy is well established. Less clear is the incidence of subsequent cancer in patients with superficial thrombophlebitis. We wanted to determine the incidence of cancer after an episode of spontaneous superficial thrombophlebitis in a large general practice population. METHODS: The objective of this study was to assess the incidence of newly diagnosed malignancies in patients within 2 years after the diagnosis of a spontaneous episode of superficial thrombophlebitis and to compare this incidence with nonexposed matched control patients and the Dutch population. The patients and their controls were identified by a search in the electronic patient records of 5 primary health care centers in Amsterdam, the Netherlands. A standardized morbidity ratio was calculated using data of the Dutch cancer registry. RESULTS: A total number of 277 patients with superficial thrombophlebitis were identified, of which 250 patients had no cancer at study entry. In 5 of these 250 patients (2%; 95% confidence interval [CI], 1%-5%), a new malignancy was diagnosed within 2 years after their superficial thrombophlebitis compared with 2% (95% CI, 1%-4%) in the control group. The standardized morbidity ratio was 1.1 (95% CI, 0.5-2.7). A recurrent episode of superficial thrombophlebitis was observed in 18 of the 250 patients, and in 1 patient cancer was diagnosed within 24 months after the first episode of superficial thrombophlebitis. CONCLUSION: We conclude that a single episode of unprovoked superficial thrombophlebitis diagnosed by a family physician is not associated with an increased risk of subsequent cancer.