A new type of drug used to treat blood clots does not put patients at a higher bleeding risk than warfarin, researchers have found
Recent trials have shown similar effectiveness and a reduced or similar risk of major bleeding complications for DOACs compared with warfarin, the authors of the new study say.
However, clinical trials involve a highly selected group of patients, so the rate of safety events such as major bleeding reported in trials often does not reflect those seen in everyday clinical practice, they say.
As a result, a team of Canadian and Australian researchers used health care data from six US and Canadian jurisdictions to identify 59,525 adults who had been diagnosed with venous thromboembolism between 1 January 2009 and 31 March 2016.
The patients had been given a new diagnosis of VTE and a prescription for a DOAC or warfarin within 30 days of the diagnosis.
The researchers studied the outcomes of 12,489 patients using direct oral anticoagulants, and 47,036 warfarin users, following patients up for an average of 85 days. During this time, all hospital admissions or ED presentations for major bleeding, and deaths from all causes within 90 days after starting treatment, were recorded.
Demographic factors, presence of other conditions, and history of major bleeding were also taken into account to minimise bias.
Of the 59,525 participants, 1,967 (3.3%) had a major bleed and 1,029 (1.7%) died during the follow-up period.
The risk of major bleeding was similar for DOACs compared with warfarin use: bleeding rates at 30 days ranged between 0.2% and 2.9% for DOACs and 0.2% and 2.9% for warfarin.
Bleeding rates at 60 days ranged between 0.4% and 4.3% for DOACs and 0.4% and 4.3% for warfarin.
No difference was found in the risk of death for DOACs compared with warfarin use.
Results remained unchanged after further analyses, including when a longer period of follow-up (180 days) was used.
The authors point out that this is an observational study, so no firm conclusions can be drawn about cause and effect, and say they cannot rule out the possibility that their results may be due to other unmeasured factors.
Further studies are also needed to understand the safety of DOACs over the longer term and among patients with advanced chronic kidney disease, they say.
Nevertheless they conclude: “This large multicentre, population based study suggests that DOAC use is not associated with higher major bleeding risk in venous thromboembolism.”