To cite this article: Kamphuisen PW, Ten Wolde M, Jacobs EMG, Ullmann EF, Bu È ller HR. Screening of high factor VIII levels is not recommended in patients with recently diagnosed pulmonary embolism. J Thromb Haemost 2003; 1: 2239±40.Dear Sir, Factor (F) VIII activity levels !150 IU dL À1 are associated with an increased risk of venous thromboembolism (VTE) [1±3]. It has been shown that 25% of the patients with a ®rst episode of venous thrombosis and 11% of the healthy population have such high FVIII levels [1]. Furthermore, high FVIII levels may increase the risk of recurrent thrombosis [2,4]. Thrombophilia screening of patients with VTE for high FVIII levels may therefore be important.FVIII is an acute-phase reactant and may be elevated due to the thrombotic event. However, high FVIII levels measured in patients with venous thrombosis at least 6 months after the event persist over time and are generally not in¯uenced by acutephase reactions [5,6]. Since thrombophilia screening is often performed shortly after the diagnosis of VTE, i.e. at presentation before the start of anticoagulant therapy, it is unclear whether measurement of FVIII at that time is reliable. In the acute phase of the thrombosis, in¯ammatory reactions can in¯uence the FVIII level, and an elevated FVIII level may merely re¯ect the consequence rather than the cause of thrombosis.We have investigated whether FVIII levels !150 IU dL À1 measured in consecutive patients suspected for pulmonary embolism (PE) were persistent over time, and, by measuring C-reactive protein (CRP) levels, to what extent an acute-phase reaction was associated with high FVIII levels. Patients with objectively con®rmed PE were compared with patients in whom this diagnosis was excluded and who had an uneventful 3-month clinical follow-up. After 3 months, another blood sample was drawn in all patients. FVIII:C levels were measured by a one-stage clotting assay, high sensitivity CRP levels were determined using latex particle-enhanced turbidimetric immunoassay (CRP-US; Roche Diagnostics, Almere, the Netherlands) on a Modular Analytics P800 analyzer (Roche Diagnostics).Fifty-one patients with PE and 102 patients with objectively excluded PE were screened. Thirty-one (61%) patients with PE and 41 (40%) of those without PE had FVIII levels !150 IU dL À1 ; 29 men and 43 women. The mean age was 55 years (range 31±84) for patients and 52 years (22±88) for controls. Twenty-®ve (61%) patients without PE had alternative diagnoses, such as pneumonia, heart failure or malignancy. Initially, mean plasma FVIII levels (AE SD) were 197 AE 26 IU dL À1 in PE patients and 194 AE 24 IU dL À1 in patients without PE Three months later, FVIII levels had clearly decreased in both groups compared with the ®rst measurement, with a mean difference of 46 IU dL À1 (95% CI 33±60) for patients with PE and 45 IU dL À1 (29±61) without PE. The mean FVIII concentration was again comparable in the two study groups. CRP levels clearly decreased after 3 months in both PE patients (10.7 AE 9 mg L À1 to 5.0 AE 6....
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