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Vitamin K intake, body mass index and warfarin maintenance dose.

ABSTRACT: Warfarin inhibits vitamin K-dependent coagulation factors. Being fat-soluble, the availability of vitamin K may vary according to body fat. We hypothesized that body mass index (BMI), a proxy of body fat, may interact with vitamin K intake in determining a warfarin maintenance (WM) dose.Patients with data on vitamin K intake, potential confounders and WM dose (n = 172) were included in linear regression models to test whether BMI modifies the relation between vitamin K intake and WM dose.Warfarin loading dose correlated with the maintenance dose (r = 0.36, p < 0.0001) but was not significantly associated with WM dose in analyses adjusted for vitamin K epoxide reductase (VKORC1) and cytochrome P450 2C9 (CYP2C9) genotypes. In fully adjusted models, BMI was associated (p = 0.001) with WM dose but vitamin K was only marginally positively associated (p = 0.06) with WM dose. We found no interaction (p > 0.05) between BMI and vitamin K intake with regard to WM dose. Inclusion of vitamin K intake in the model only slightly improved the amount of variance (1.1%) explained by age, gender, BMI, race, physical activity, energy intake and VKORC1 and CYP2C9 genotypes.Our data suggest that body fat does not affect the relation between vitamin K intake and WM dose.

SUBMITTER: Kabagambe EK

PROVIDER: S-EPMC4038335 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Vitamin K intake, body mass index and warfarin maintenance dose.

Kabagambe Edmond K EK Beasley T Mark TM Limdi Nita A NA

Cardiology 20130919 4

<h4>Background</h4>Warfarin inhibits vitamin K-dependent coagulation factors. Being fat-soluble, the availability of vitamin K may vary according to body fat. We hypothesized that body mass index (BMI), a proxy of body fat, may interact with vitamin K intake in determining a warfarin maintenance (WM) dose.<h4>Methods</h4>Patients with data on vitamin K intake, potential confounders and WM dose (n = 172) were included in linear regression models to test whether BMI modifies the relation between v ...[more]

PMID: 24052022

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Project description:BackgroundSeveral studies have demonstrated an association between body mass index (BMI) and warfarin therapeutic dose, but none evaluated the association of BMI with the clinically important outcome of major bleeding in a community setting. To address this evidence gap, we conducted a case-control study to evaluate the association between BMI and major bleeding risk among patients receiving warfarin.MethodsWe used a case-control study design to evaluate the association between obesity (BMI >30.0 kg/m2) and major bleeding risk among 265 cases and 305 controls receiving warfarin at Group Health, an integrated healthcare system in Washington State. Multivariate logistic regression was used to adjust for potential confounders derived from health plan records and a self-report survey. In exploratory analyses we evaluated the interaction between genetic variants potentially associated with warfarin bleeding (CYP2C9, VKORC1, and CYP4F2) and obesity on the risk of major bleeding.ResultsOverall, the sample was 55% male, 94% Caucasian, and mean age was 70 years. Cases and controls had an average of 3.4 and 3.7 years of warfarin use, respectively. Obese patients had significantly lower major bleeding risk relative to non-obese patients (odds ratio [OR] 0.60, 95% confidence interval [CI] 0.39-0.92). The OR was 0.56 (95% CI 0.35-0.90) in patients with ≥1 year of warfarin use, and 0.78 (95% CI 0.40-1.54) in patients with <1 year of warfarin use. An exploratory analysis indicated a statistically significant interaction between CYP4F2*3 genetic status and obesity (P = .049), suggesting a protective effect of obesity on the risk of major bleeding among those wild type for CYP4F2*3, but not among variants.ConclusionsOur findings suggest that BMI is an important clinical factor in assessing and managing warfarin therapy. Future studies should confirm the major bleeding associations, including the interaction between obesity and CYP4F2*3 status identified in this study, and evaluate potential mechanisms.

Project description:ImportanceBody mass index (BMI) is used to diagnose obesity in adolescents worldwide, despite evidence that weight does not scale with height squared in adolescents. To account for this, health care providers diagnose obesity using BMI percentiles for each age (BMI z scores), but this does not ensure that BMI is accurate in adolescents.ObjectiveTo compare the accuracy of BMI vs other body fat indices of the form body mass divided by heightn in estimating body fat levels in adolescents.Design, setting, and participantsCross-sectional data from the 1999 to 2006 US National Health and Nutrition Examination Survey were analyzed between September 2015 and December 2016.Main outcomes and measuresDual-energy x-ray absorptiometry and anthropometric data were used to determine changes in body fat levels, body proportions, and the scaling relationships among body mass, height, and percent body fat. To assess the merits of each adiposity index, 3 criteria were used: stability with age, accuracy in estimating percent body fat, and accuracy in classifying adolescents as overweight vs normal weight.ResultsParticipants included 2285 non-Hispanic white participants aged 8 to 29 years. Percent body fat varied with both age and height during adolescence, invalidating the standard weight-to-height regression as the way of finding the optimal body fat index. Because the correct regression model (percent body fat is proportional to mass divided by heightn) suggested that percent body fat scales to height with an exponent closer to 3, we therefore focused on the tri-ponderal mass index (TMI; mass divided by height cubed) as an alternative to BMI z scores. For ages 8 to 17 years, TMI yielded greater stability with age and estimated percent body fat better than BMI (R2?=?0.64 vs 0.38 in boys and R2?=?0.72 vs 0.66 in girls). Moreover, TMI misclassified adolescents as overweight vs normal weight less often than BMI z scores (TMI, 8.4%; 95% CI, 7.3%-9.5% vs BMI, 19.4%; 95% CI, 17.8%-20.0%; P?<?.001) and performed equally as well as updated BMI percentiles derived from the same data set (TMI, 8.4%; 95% CI, 7.3%-9.5% vs BMI, 8.0%; 95% CI, 6.9%-9.1%; P?=?.62).Conclusions and relevanceThe tri-ponderal mass index estimates body fat levels more accurately than BMI in non-Hispanic white adolescents aged 8 to 17 years. Moreover, TMI diagnoses adolescents as overweight more accurately than BMI z scores and equally as well as updated BMI percentiles but is much simpler to use than either because it does not involve complicated percentiles. Taken together, it is worth considering replacing BMI z scores with TMI to estimate body fat levels in adolescents.

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Vitamin K intake, body mass index and warfarin maintenance dose.

Publications

Vitamin K intake, body mass index and warfarin maintenance dose.

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