Optimization of anticoagulation with warfarin for stroke prevention: pharmacogenetic considerations

Emergency colectomies in the NOAC era: a nationwide analysis demonstrating increased complications

BACKGROUND

The use of Non-vitamin K antagonist oral anticoagulants (NOAC) has increased substantially since their introduction in 2010. The lack of readily available reversal agents poses a challenge in perioperative management. The aim of this study was to evaluate the impact of NOACs on the outcomes of emergency colectomies.

METHODS

All adult patients on long-term anticoagulation who underwent emergency colectomies were identified from the Nationwide Inpatient Sample (NIS) database from 2002 to 2018. Long-term anticoagulation was defined using ICD-9/10 codes. Two cohorts were compared: anticoagulated patients in the pre-NOAC era (2002-2010) and anticoagulated patients in the NOAC era (2010-2018). Outcomes of interest were postoperative surgical complications, mortality and need for transfusion.

RESULTS

Of 13,218 patients on long-term anticoagulation, 3,264 patients were treated in the pre-NOAC era and 9,954 in the NOAC era. Over the study period, there was a significant increase in the proportion of anticoagulated patients undergoing emergency colectomies (R² = 0.91). On univariate analysis, anticoagulated patients in the NOAC era were medically more comorbid and had higher rates of postoperative surgical complications (73.3% vs 60.3%, p < 0.001) and mortality (8.2% vs. 6.7%, p = 0.006), but had lower rates of postoperative bleeding (3.5% vs. 4.4%, p = 0.002) and transfusions (38.1% vs. 45.4%, p < 0.001). On multivariable regression, after accounting for clinically significant covariates, anticoagulation in the NOAC era was associated with decreased rates of postoperative bleeding (OR 0.70, 95%CI 0.57-0.88) and transfusions (OR 0.71 95%CI 0.64-0.77) but remained an independent predictor of increased overall postoperative complications (OR 1.26, 95%CI 1.14-1.39).

CONCLUSION

Prevalence of long-term anticoagulation in patients undergoing emergency colectomies is increasing. Although associated with lower rates of postoperative bleeding and transfusions, anticoagulation in the NOAC era is associated with higher rates of overall postoperative complications. Evidence-based guidelines for perioperative management of patients on NOACs in the emergency colorectal surgery setting are needed.

Pharmacogenetic algorithm for predicting daily dose of warfarin in Caucasian patients of Czech origin

OBJECTIVES

Warfarin use is limited by a low therapeutic index and significant interindividual variability of the daily dose. The most important factor predicting daily warfarin dose is individual genotype, polymorphisms of genes CYP2C9 (warfarin metabolism) and VKORC1 (sensitivity for warfarin). Algorithms using clinical and genetic variables could predict the daily dose before the initiation of therapy. The aim of this study was to develop and validate an algorithm for the prediction of warfarin daily dose in Czech patients.

METHODS

Detailed clinical data of patients with known and stable warfarin daily dose were collected. All patients were genotyped for polymorphisms in genes CYP2C9 and VKORC1.

RESULTS

Included patients were divided into derivation (n=175) and validation (n=223) cohorts. The final algorithm includes the following variables: Age, height, weight, treatment with amiodarone and presence of variant alleles of genes CYP2C9 and VKORC1. The adjusted coefficient of determination is 72.4% in the derivation and 62.3% in the validation cohort (p<0.001).

CONCLUSIONS

Our validated algorithm for warfarin daily dose prediction in our Czech cohort had higher precision than other currently published algorithms. Pharmacogenetics of warfarin has the potential in the clinical practice in specialized centers.

The bleeding risk during warfarin therapy is associated with the number of variant alleles of CYP2C9 and VKORC1 genes

BACKGROUND

Warfarin is commonly used for the treatment and prevention of arterial and venous thromboembolism but its use is hindered by the risk of bleeding. The main reason for this risk is a narrow therapeutic index and a wide response variability after warfarin treatment. These shortcomings affect clinical outcomes including bleeding complications and may be associated with variant polymorphisms in the CYP2C9 and VKORC1 genes.

AIM

It was the aim of this study to assess the impact of the total variant allele count of CYP2C9 and VKORC1 genes on bleeding related to warfarin treatment.

METHODS

In a retrospective cohort-design study, patients were genotyped for polymorphisms in genes CYP2C9 (*1, *2, *3) and VKORC1 (haplotype A, B). Extensive clinical data were obtained. Adjusted hazard ratios (HR) for the occurrence of major bleeding events (MBE) were counted separately for the induction and maintenance phases of warfarin therapy.

RESULTS

Out of the 329 patients in our clinical database, 194 patients were eligible and included in the analysis. MBE occurred in 51 patients (26.3%) during a mean follow-up of 26 months: 6 patients (11.8%) experienced early MBE during warfarin initiation, and 45 MBE occurred during the maintenance phase. The adjusted HR for MBE risk for patients with any CYP2C9 variant allele was 1.962 [95% confidence interval (CI) 1.08-3.56, p = 0.027]; for the VKORC1 AA haplotype, HR was 1.841 (95% CI 0.97-3.48, p = 0.06), while for 3 variant allele carriers of both genes, HR was 4.34 (95% CI 1.95-9.65, p < 0.001). Despite the insignificant association of the VKORC1 genotype with bleeding in our study, we have noted a warfarin dose-dependent effect with risk significance ascending: CYP2C9 *1/*1 + VKORC1 B/B < CYP2C9 *1/*1 + VKORC1 A/B < CYP2C9 *1/*2 + VKORC1 B/B.

CONCLUSION

Patients who are carriers of 3 variant alleles of the genes CYP2C9 and VKORC1 exhibited a significantly higher risk of MBE during the initiation and maintenance phases of warfarin therapy. Vigilant and careful management of patients with a higher variant allele count, including switching to newer anticoagulants, could be considered in this high-risk cohort.

Clinical utility of pharmacogenetic biomarkers in cardiovascular therapeutics: a challenge for clinical implementation

In the past decade, significant strides have been made in the area of cardiovascular pharmacogenomic research, with the discovery of associations between certain genotypes and drug-response phenotypes. While the motivations for personalized and predictive medicine are promising for patient care and support a model of health system efficiency, the implementation of pharmacogenomics for cardiovascular therapeutics on a population scale faces substantial challenges. The greatest obstacle to clinical implementation of cardiovascular pharmacogenetics may be the lack of both reproducibility and agreement about the validity and utility of the findings. In this review, we present the scientific evidence in the literature for diagnostic variants for the US FDA-labeled cardiovascular therapies, namely CYP2C19 and clopidogrel, CYP2C9/VKORC1 and warfarin, and CYP2D6/ADRB1 and β-blockers. We also discuss the effect of HMGCR/LDLR in decreasing the effectiveness of low-density lipoprotein cholesterol with statin therapy, the SLCO1B1 genotype and simvastatin myotoxicity, and ADRB1/ADD1 for antihypertensive response.