medwireNews: People with diabetes and atrial fibrillation have a lower risk for vascular complications if they are given non-vitamin K antagonist oral anticoagulants (NOACs) rather than warfarin, show results of a population-based study.
Yu-Kang Tu (National Taiwan University, Taipei) and co-researchers obtained population-wide data from Taiwan’s National Health Insurance Research Database and used inverse probability of treatment weighting to create two groups with balanced baseline characteristics: one group of 19,909 NOAC users and one of 10,300 warfarin users, all with diabetes and atrial fibrillation.
During up to 6–7 years of follow-up, people taking NOACs had a significant 16% reduced risk for a macrovascular event, at an incidence rate of 120.7 per 1000 person–years, compared with 143.8 per 1000 person–years among those taking warfarin.
They also had a 21% reduced risk for microvascular events (36.1 vs 44.8 events per 1000 person–years) and a 22% reduced all-cause mortality risk (87.4 vs 113.7 events per 1000 person–years).
Moreover, NOAC use was associated with a small but significant 9% reduction in the risk for glycemic emergencies relative to warfarin use, at rates of 23.5 versus 26.3 events per 1000 person–years.
“Evidence suggests that vitamin K plays a role in improving insulin sensitivity and glucose tolerance by regulating vitamin K–dependent proteins, anti-inflammatory signaling, and lipid metabolism,” explain the researchers in the Annals of Internal Medicine.
“However, warfarin interferes with vitamin K function, whereas NOACs act by mechanisms independent of vitamin K,” they say, suggesting that this may explain the differences in outcomes between the two groups.
An alternative analysis using propensity score matching produced similar results, albeit the association between NOAC use and a reduced risk for glycemic emergencies was not statistically significant.
However, Tu et al note that their analyses did not account for the fact that 46% of warfarin users switched to using NOACs during follow-up.
“Nevertheless, such a conservative approach still showed a significantly lower hazard for composite complication outcomes and mortality in NOAC users than in warfarin users,” they say, and suggest that the real effect may be larger.
The benefits of NOACs remained consistent when looking at the individual medications, and the team found significant reductions in the risks for the specific outcomes of coronary artery disease, stroke, dialysis, lower extremity amputation, and both cardiovascular and noncardiovascular mortality.
“Therefore, NOAC[s] may be a better therapeutic choice than warfarin for decreasing these complications and mortality in patients with [atrial fibrillation] and [diabetes] requiring oral anticoagulant treatment,” the researchers conclude.
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Ann Intern Med 2022; doi:10.7326/M21-3498