To the Editor: Dr Eichinger and colleagues1 found that D-dimer levels measured after a single occurrence of idiopathic venous thromboembolism (VTE) were related to future risk of recurrent VTE. Their D-dimer cutoff levels (250 ng/mL, 500 ng/mL, and 750 mg/mL), however, are assay-specific. In ruling out VTE, for example, optimal threshold values for some enzyme-linked immunoassays (ELISAs) are as low as 40 ng/mL but may be more than 500 ng/mL for others.2 Similarly, different quantitative non-ELISAs may require different cutoff values in the exclusion of VTE.3 - 4 The threshold used by Eichinger et al to define those patients at low risk for recurrence (ie, <250 mg/mL) is half the value used to exclude VTE (<500 ng/mL) with that particular assay (Asserachrom D-dimer, Boehringer Mannheim, Mannheim, Germany).5
Thus it may be possible to state the author's conclusions in more general terms, ie, that D-dimer levels less than half the threshold level used for the exclusion of VTE may predict low risk of recurrence. Such a rule might apply to any quantitative assay that has a validated high-sensitivity cutoff for exclusion of VTE, and would allow use of other assays irrespective of their particular cutoff values.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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