VTE in Psychiatric Patients Effectively Diagnosed Using New Marker

Soluble fibrin monomer complex (SFMC), a suggested new candidate marker for venous thromboembolism (VTE), is effective at diagnosing the condition in psychiatric patients with positive D-dimer results, according to a study published in the journal Vascular Health and Risk Management.

“D-dimer has the disadvantage of low specificity; however, we hypothesized that the combination of D-dimer and SFMC would increase its usefulness for diagnosing VTE,” the researchers wrote.

In this prospective study, researchers assessed 109 patients at psychiatric department between Aug. 2017 and Dec. 2019. The investigators concurrently measured levels of of D-dimer and SFMC. They noted that plasma levels of D-dimer and SFMC were measured using NANOPIA® D-dimer and NANOPIA® SF.

The study was conducted in the following way: Subjects with positive D-dimer score of (≥ 1.0 μg/mL) results underwent contrast computed tomography for confirmation of VTE within 12 hours of D-dimer measurement. The researchers performed a receiver operating characteristic curve analysis to analyze examine the efficacy of SFMC on VTE diagnosis.

Results Provide Useful Cutoff Values

According to the results of a receiver operating characteristic curve analysis, the area under the curves was 0.848 for SFMC (p<0.001, 95% CI 0.722-0.974), and the optimal cutoff value was 10.0 μg/mL (sensitivity 58.8%, specificity 100%, positive predictive value 100%, negative predictive value 77.4%).

The researchers concluded that: “This is the first study to explore the usefulness of the combination of D-dimer and SFMC for the diagnosis of VTE. The results of this study provide cutoff values of SFMC that are sufficient for diagnosing VTE clinically, with a sensitivity of 58.8% and specificity of 100% among patients with psychiatric disorders and positive D-dimer results. Although previous studies have shown inconsistent results on the usefulness of SFMC, the ROC analysis conducted in the current study shows that SFMC is a useful marker for the diagnosis of VTE.”

They added that: “It is unclear why the specificity of the cutoff value for SFMC in this study was high. Possible reasons that affected the results were that (1) VTE screening by D-dimer was performed simultaneously with SFMC measurement, and that (2) the subjects were psychiatric patients with few physical factors that elevate SFMC other than VTE compared to non-psychiatric patients. Since few studies have examined the usefulness of SFMC, further studies are warranted to validate these findings.”

In terms of strengths and limitations, the researchers cited the study’s designed, which was prospective in nature, and the detailed examination of VTE as the study’s strong points.

The study, according to the investigators, was limited in scope considering that only 14% of patients admitted to the psychiatric department participated. They stated that selection bias may have affected the study’s findings.

Moreover, the researchers believe that VTE may have been missed because patient’s with D-dimer levels of < 1.0 µg/mL failed to undergo contrast-enhanced CT.

Furthermore, the researchers noted that some participants might exhibit cofounding factors that increase both D-dimer and SFMC levels, respectively.

Overall, the researchers wrote of the limitations that: “These methodological issues should be resolved through future carefully designed studies.”