Summary
Current plasma markers for diagnosis of deep venous thrombosis (DVT) allow for exclusion
of the diagnosis, but lack adequate specificity to establish the diagnosis. Thus,
a prospective study was performed to determine the sensitivity and specificity of
plasma assays for D-dimer, soluble P-selectin (P-selectin), and total microparticles
in patients with documented DVT by duplex ultrasound. Three groups of individuals
were examined: 30 normals; 22 positive for DVT on duplex ultrasound (Group 2); and
21 symptomatic, but negative on duplex ultrasound for DVT (Group 3). Group 1 individuals
had D-dimer values of 1.53±0.12 mg/l and P-selectin values of 0.34±0.05 ng/mg total
protein. Group 2 vs. Group 3 individuals had D-dimer values of 7.57±2.03 vs. 3.19±0.79
mg/l, p=0.02; P-selectin values of 0.98±0.11 vs. 0.55±0.08 ng/mg total protein, p<0.01;
and microparticle values of 129±17% vs. 99±12% of control, p=ns. Using a logistic
regression model with dichotomous variables, we determined a sensitivity of 73%, specificity
of 81%, and accuracy of 77% when combining D-dimer, soluble P-selectin, and total
microparticles to differentiate Group 2 from Group 3 patients. Logistic regression
using continuous variables yielded similar results (p=0.05).This study demonstrates
that plasma markers for DVT can be developed and achieve moderate sensitivity and
specificity in diagnosing DVT. However for clinical applicability, the sensitivity/specificity
will need to be improved. These studies also suggest the importance of soluble P-selectin
in assessing DVT in humans.
Keywords
Deep venous thrombosis - D-dimer - P-selectin - microparticles - clinical study