Similar to earlier findings with warfarin and acenocoumarol, phenprocoumon maintenance dosage depended on polymorphisms in the VKORC1 gene. CYP2C9 and CYP4F2 were of modest relevance.
Summary
In the Netherlands, several reports have described a potentiation of acenocoumarol‐induced anticoagulation by co‐medication of omeprazole or esomeprazole and competitive inhibition of CYP2C19 has been suggested as a possible mechanism for this interaction. We conducted an observational cohort study to investigate the effects of various proton pump inhibitors (PPIs) on acenocoumarol effectiveness. All 2755 subjects from the Rotterdam Study who received acenocoumarol maintenance treatment between April 1st, 1991 and September 9th, 2009 were followed for events of an international normalized ratio (INR) ≥ 6, until death, end of treatment, or end of the study period. The Andersen–Gill extension of the Cox proportional hazards model was used to calculate risks for repeated events of overanticoagulation in relation to concomitant PPI use. The risk for overanticoagulation was most pronounced for esomeprazole (HR 1·99, 95% CI 1·55–2·55) and lansoprazole (HR 1·49, 95% CI 1·05–2·10). There was also a lower and non‐significant risk increase for the other PPIs. We did not detect a modification of these results by CYP2C19*2 genotype. Caution should be paid to co‐medication with esomeprazole and lansoprazole during acenocoumarol treatment and possibly also with other PPIs.
To cite this article: Biedermann JS, van Rein N, van den Besselaar AMHP, Buhre PN, de Maat MPM, van der Meer FJM, Leebeek FWG, Kruip MJHA. Impact of point-of-care international normalized ratio monitoring on quality of treatment with vitamin K antagonists in non-self-monitoring patients: a cohort study. J Thromb Haemost 2016; 14: 695-703.
EssentialsIt is unclear if point-of-care (POC) monitoring is safe in non-self-monitoring (NSM) patients. We compared time in therapeutic range (TTR) and outcome during laboratory and POC monitoring. Median TTR was lower during POC monitoring (77.9 vs. 81.0%), but adverse event rates were similar. POC monitoring is a safe and effective alternative to laboratory monitoring in NSM patients.Summary. Background: Point-of-care (POC) international normalized ratio (INR) monitoring by healthcare professionals could eliminate the need for venous blood sampling in non-self-monitoring (NSM) patients on vitamin K antagonists (VKA). However, few studies have investigated the impact of POC INR monitoring on the quality of treatment in these patients and real-world data on this issue are lacking. Objectives: To investigate the safety, efficacy and quality of anticoagulant control during POC INR monitoring as compared with laboratory INR monitoring in NSM patients. Methods: We performed a retrospective cohort study using data from the anticoagulation clinic of the Star-Medical Diagnostic Center (Rotterdam, the Netherlands). Patients who received treatment with VKA between 29 May 2012 and 29 May 2014 were eligible. Percentage of time in therapeutic range (TTR) and incidence rates of major clinical events (all-cause mortality, hospitalization, major bleeding and ischemic stroke) were compared for the year before and year after introduction of POC monitoring. Cox proportional hazard models were used to estimate hazard ratios and 95% confidence intervals for major clinical events between exposure groups. Results: In total, 1973 patients during the 1-year laboratory-monitoring observation period and 1959 patients during the 1-year POC-monitoring observation period were included. Median TTR was significantly lower during POC monitoring (77.9%; 95% CI, 67.2-87.4) than during laboratory INR monitoring (81.0%; 95% CI, 71.1-90.5). Adjusted hazard ratios for major clinical events were all around unity. Conclusions: Although associated with lower TTR, POC INR monitoring is a safe and effective alternative to laboratory INR monitoring in NSM patients on VKA.
The EU-PACT acenocoumarol algorithm performs just as accurately in this study as in the original study, which implies applicability in various populations.
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