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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Prothrombin Time and International Normalized Ratio as Predictors of Factor VII Coagulation Activity in Pediatric
Yotam Bronstein1, Dana Elhadad1, Eyas Midlij1
1Department of Pediatrics, Sanz Medical Center-Laniado Hospital, Netanya, Israel.
Insights
Diagnosing Factor VII (FVII) deficiency requires direct measurement of FVII:C levels, as standard prothrombin time (PT) and international normalized ratio (INR) tests are unreliable predictors in pediatric patients undergoing surgery.
Area of Science:
- Hematology
- Pediatric Surgery
- Coagulation Disorders
Background:
- Factor VII (FVII) deficiency presents with normal activated partial thromboplastin time (aPTT) and prolonged prothrombin time (PT).
- Diagnosis relies on Factor VII coagulation activity (FVII:C) measurements, which are costly and time-consuming.
- Identifying FVII deficiency is crucial for managing bleeding risks, especially before surgical procedures.
Purpose of the Study:
- To investigate the correlation between PT, INR, and FVII:C in pediatric patients undergoing otolaryngology surgery.
- To explore alternative, potentially simpler methods for identifying FVII deficiency preoperatively.
- To assess the predictive accuracy of PT and INR for FVII deficiency in this cohort.
Main Methods:
- Retrospective analysis of 96 pediatric patients with normal aPTT and prolonged PT undergoing preoperative coagulation workup (2016-2020).
- Collected FVII:C data alongside PT and INR values.
- Utilized Spearman correlation and receiver operating characteristic (ROC) curve analysis to evaluate PT and INR as predictors of FVII deficiency.
Main Results:
- A significant negative correlation was found between FVII:C and both PT and INR.
- While ROC analysis showed statistically significant results for PT (0.653) and INR (0.669), no optimal cutoff point was identified for high sensitivity and specificity.
- 67.7% of patients had normal FVII:C, while 32.3% had decreased levels.
Conclusions:
- Prothrombin time (PT) and international normalized ratio (INR) alone are insufficient to reliably predict clinically relevant Factor VII coagulation activity (FVII:C) levels.
- Direct measurement of FVII:C is necessary for diagnosing FVII deficiency when PT is abnormal.
- Accurate FVII:C levels are essential for determining appropriate surgical prophylactic treatment in patients with suspected or confirmed FVII deficiency.
Background:
Factor VII (FVII) deficiency is characterized by normal activated partial thromboplastin time (aPTT) and prolonged prothrombin time (PT) values. It is diagnosed by determining protein level and coagulation activity (FVII:C). FVII:C measurements are expensive and time consuming.
Objectives:
To analyze correlations between PT, international normalized ratio (INR), and FVII:C in pediatric patients before otolaryngology surgery and to establish alternative methods for identifying FVII deficiency.
Methods:
FVII:C data were collected from 96 patients with normal aPTT and prolonged PT values during preoperative otolaryngology surgery coagulation workup between 2016 and 2020. We compared demographic and clinical parameters using Spearman correlation coefficient and receiver operating characteristic (ROC) curve analysis to determine the accuracy of PT and INR values to predict FVII deficiency.
Results:
The median values of PT, INR and FVII:C were 13.5 seconds, 1.14, and 67.5%, respectively. In total, 65 participants (67.7%) displayed normal FVII:C compared to 31 (32.3%) with decreased FVII:C. A statistically significant negative correlation was observed between FVII:C and PT values and between FVII:C and INR. Despite statistically significant ROC of 0.653 for PT (P-value = 0.017, 95% confidence interval [95%CI] 0.529-0.776) and 0.669 for INR (P-value = 0.08, 95%CI 0.551-0.788), we were unable to determine an optimal cutoff point to predict FVII:C deficiency with high sensitivity and high specificity.
Conclusions:
We could not identify a PT or INR threshold to best predict clinically relevant FVII:C levels. When PT is abnormal, determining FVII:C protein levels is needed for diagnosing FVII deficiency and considering surgical prophylactic treatment.
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