Should we still be utilizing warfarin in the type 2 diabetic patient?

Hyperglycemia and Venous Thromboembolism

Patients with diabetes mellitus (DM) have chronically increased blood glucose and multiple physiologic alterations that place them at elevated risk for vascular disease. Traditionally, this vascular risk has mainly referred to chronic atherosclerosis and embolic arterial disease. Retrospective studies have suggested an increased risk of a pulmonary embolism (PE) and deep vein thrombosis (DVT), collectively termed venous thromboembolism (VTE), in patients with DM, but this association has been difficult to demonstrate with comorbidities such as obesity in meta-analysis. Clinical studies have demonstrated worse outcomes for patients with DM who suffer from VTE. In vitro studies show multiple physiologic abnormalities with chronic inflammation, endothelial dysfunction, dysfunction in the coagulation cascade, as well as other changes that drive a vicious cycle of hypercoagulability. Aggressive medical management of DM can improve vascular outcomes, and some anti-hyperglycemic therapies may modify VTE risk as well. Anticoagulation strategies are similar for patients with DM, but with some added considerations, such as high rates of comorbid renal dysfunction. More research is needed to definitively categorize DM as a risk factor for VTE and elucidate specific therapeutic strategies.

Required warfarin dose and time in therapeutic range in patients with diagnosed Nonalcoholic Fatty Liver Disease (NAFLD) or Nonalcoholic Steatohepatitis (NASH)

Warfarin has been widely used to treat thromboembolism. The effect of nonalcoholic fatty liver disease (NAFLD) or nonalcoholic steatohepatitis (NASH), on warfarin dosing remains unknown. This study aims to examine the effects of NAFLD/NASH on the average daily dose (ADD) of warfarin and the time in therapeutic range (TTR). This is a retrospective study utilizing an administrative data. We included patients with at least 2 months of warfarin dispensing and two subsequent consecutive INR measures. The ADD of warfarin to achieve therapeutic range INR levels, and TTR were compared between patients with and without NAFLD/NASH in four subgroups of patients accounting for the presence of obesity and diabetes. Generalized linear models (GLM) with Propensity score (PS) fine stratification were applied to evaluate the relative differences (RD) of warfarin ADD and TTR (>60%) in four subgroups. A total of 430 NAFLD/NASH patients and 38,887 patients without NAFLD/NASH were included. The ADD and TTR, were not significant in the overall cohort between those with and without NAFLD/NASH. However, GLM results in patients without diabetes or obesity (N = 26,685) showed a significantly lower warfarin ADD (RD: -0.38; 95%CI: -0.74–-0.02) and shorter TTR (OR: 0.71; 95%CI: 0.52–0.97) in patients diagnosed with NAFLD/NASH. The effects of NAFLD/NASH on warfarin dose or TTR were observed in patients without obesity and diabetes. Obesity and diabetes appear to be significant modifiers for the effects of NAFLD/NASH on warfarin dose and TTR.

Comparative effectiveness and safety of non-vitamin-K antagonist oral anticoagulants and warfarin in older adults with atrial fibrillation and diabetes

OBJECTIVE

To evaluate comparative effectiveness and safety of non-vitamin-K antagonist oral anticoagulants (NOACs) versus warfarin in Medicare beneficiaries with non-valvular atrial fibrillation (NVAF) and comorbid diabetes mellitus (DM).

METHODS

A retrospective cohort study using 2014-2016 5% national Medicare data was undertaken. NVAF patients with DM aged ≥65 years having at least one prescription for NOACs or warfarin between July 2014 and December 2015 were included in the study. Propensity score matching was used to balance demographic and baseline clinical characteristics of patients in two treatment groups. Cardiovascular outcomes including stroke/systemic embolism (SE) and myocardial infarction (MI) were evaluated to measure effectiveness. Assessment of safety outcomes included intracranial hemorrhage (ICH), major gastrointestinal bleeding (MGB), bleeding from other sites (OB) and all-cause mortality. Stratified Cox proportional hazards models were used to estimate hazard ratios for the outcomes in the matched cohort.

RESULTS

The matched sample consisted of 4582 patients (2291 pairs). Compared to warfarin, NOACs had a significantly lower risk of stroke/SE (hazard ratio (HR): 0.373, 95% confidence interval (CI): 0.247-0.564, p < .001) and all-cause mortality (HR: 0.783, CI: 0.656-0.873, p = .007). NOACs were found to significantly reduce the risk of ICH (HR: 0.500, CI: 0.300-0.834, p = .008) and OB (HR: 0.608, CI: 0.424-0.870, p = .007), but no difference was observed in the risk of MGB (HR: 0.862, CI: 0.640-1.160, p = .326) between NOACs and warfarin. The composite outcome demonstrated superior overall effectiveness and safety of NOAC therapy compared to warfarin therapy (HR: 0.685, CI: 0.587-0.801, p < .001).

CONCLUSION

Oral anticoagulation therapy with NOACs was found to be more effective than warfarin therapy among older adults with NVAF and comorbid DM.

Stroke in the patient with diabetes (Part 2) - Prevention and the effects of glucose lowering therapies

There is a higher incidence of stroke in both the type 2 diabetic and the non-diabetic insulin resistant patient which is accompanied by higher morbidity and mortality. Stroke primary prevention can be achieved by controlling atrial fibrillation and hypertension, and the utilization of statins and anticoagulant therapies. Utilizing pioglitazone and GLP-1 receptor agonists reduce the risk of stroke while the utilization of metformin, α-glucosidase inhibitors, DPP-4 and SGLT-2 inhibitors have no effect. Insulin use may be a marker of increased risk of stroke, but not necessarily causative. Utilizing intravenous insulin to normalize plasma glucose levels in the acute phase of a stroke does not improve the outcome. Antiplatelet agents are not proven to be of benefit in primary prevention whereas the use of direct-acting oral anticoagulants to avoid stroke and the early use of tpA in the acute phase have been shown to be beneficial.

Concerns about clinical efficacy and safety of warfarin in diabetic patients with atrial fibrillation

Atrial fibrillation (AF) is one of the most common arrhythmias in elderly people. The risk of thromboembolic stroke is increased in AF patients, especially those with diabetes. Anticoagulant therapy, such as warfarin and non-vitamin K oral anticoagulants (NOACs), is recommended for diabetic patients with AF. However, recent guidelines do not preferentially recommend NOACs over warfarin for diabetic patients. Variability of glycemic control in diabetic patients could affect the pharmacokinetics and anticoagulant activity of warfarin, therefore, the risk-benefit balance of warfarin is prone to be compromised in diabetic patients with AF. Furthermore, since warfarin inhibits the vitamin K-dependent gamma-glutamyl carboxylation of proteins, including osteocalcin and matrix Gla protein, use of warfarin may increase the risk of osteoporotic bone fracture and vascular calcification, both of which are the leading causes of morbidity that diminish the quality of life in diabetic patients. Even though the cost of NOACs is high, NOACs may be preferable to warfarin for the treatment of diabetic patients with AF.