medwireNews: Older patients and those with cardiovascular disease are most likely to have an increased risk for lower limb amputation when newly prescribed canagliflozin, relative to a glucagon-like peptide (GLP)-1 receptor agonist, research shows.
However, the absolute increase rates of amputations associated with canagliflozin use is small overall, report Michael Fralick and colleagues from Harvard Medical School, in Boston, Massachusetts, USA.
Their study included data from one Medicare and two commercial claims databases for 155,420 patients with type 2 diabetes who initiated canagliflozin between 2013 and 2017, and for the same number of patients newly prescribed a GLP-1 receptor agonist, matched on the basis of propensity scoring.
The patients were divided into four subgroups according to age and cardiovascular disease status, and followed up for an average of approximately 275 days.
The researchers found that the only patients with a significantly higher rate of lower limb amputations with canagliflozin relative to GLP-1 inhibitors were those aged 65 years or older with cardiovascular disease at baseline.
For this subgroup, the lower limb amputation rate was 9.32 per 1000 person–years with canagliflozin and 5.46 per 1000 person–years with GLP-1 inhibitors, corresponding to an absolute rate difference of 3.66 amputations per 1000 person-years and a significant 73% higher risk for amputation with canagliflozin.
On the basis of these numbers, “it is expected that one additional person will incur an amputation for every 556 adults receiving canagliflozin rather than a GLP-1 agonist over six months (that is, 18 more amputations per 10 000 people who received canagliflozin),” Fralick et al remark.
For patients aged 65 years and older without baseline cardiovascular disease, the amputation rate difference between patients who received canagliflozin and those who received GLP-1 inhibitors was a nonsignificant 0.47 per 1000 person–years.
For those younger than 65 years of age, it was 1.06 per 1000 person–years in the subgroup with baseline cardiovascular disease and 0.12 per 1000 person–years in the subgroup without cardiovascular disease, and again both differences were nonsignificant.
Writing in The BMJ, Fralick and co-authors say their study “helps to put into context the rate of amputation associated with the initiation of canagliflozin in routine care and can inform decision making between physicians and patients before this drug is started.”
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