Intended for healthcare professionals

CCBYNC Open access
Research

Risk of amputation with canagliflozin across categories of age and cardiovascular risk in three US nationwide databases: cohort study

BMJ 2020; 370 doi: https://doi.org/10.1136/bmj.m2812 (Published 25 August 2020) Cite this as: BMJ 2020;370:m2812
  1. Michael Fralick, general internist and assistant professor1 2,
  2. Seoyoung C Kim, associate professor1,
  3. Sebastian Schneeweiss, professor1,
  4. Brendan M Everett, associate professor3,
  5. Robert J Glynn, professor1,
  6. Elisabetta Patorno, assistant professor1
  1. 1Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 1620 Tremont Street, Suite 3030, Boston, MA 02120, USA
  2. 2Sinai Health System and Department of Medicine, University of Toronto, Toronto, ON, Canada
  3. 3Divisions of Cardiovascular and Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
  1. Correspondence to: M Fralick mif823{at}mail.harvard.edu (or @fralickmike on Twitter)
  • Accepted 24 June 2020

Abstract

Objective To estimate the rate of lower limb amputation among adults newly prescribed canagliflozin according to age and cardiovascular disease.

Design Population based, new user, cohort study.

Data sources Two commercial and Medicare claims databases, 2013-17.

Participants Patients newly prescribed canagliflozin were propensity score matched 1:1 with patients newly prescribed a glucagon-like peptide-1 (GLP-1) receptor agonist. Hazard ratios and rate differences per 1000 person years were computed for the rate of lower limb amputation in the following four groups: group 1, patients aged less than 65 years without baseline cardiovascular disease; group 2, patients aged less than 65 with baseline cardiovascular disease; group 3, patients aged 65 or older without baseline cardiovascular disease; group 4, patients aged 65 or older with baseline cardiovascular disease. Within each group, pooled hazard ratio and rate difference per 1000 person years were calculated by meta-analysis.

Intervention Canagliflozin versus a GLP-1 agonist.

Main outcome measures Lower limb amputation requiring surgery.

Results Across the three databases, 310 840 propensity score matched adults who started canagliflozin or a GLP-1 agonist were identified. The hazard ratio and rate difference per 1000 person years for amputation in adults receiving canagliflozin compared with a GLP-1 agonist for each group was: group 1, hazard ratio 1.09 (95% confidence interval 0.83 to 1.43), rate difference 0.12 (−0.31 to 0.55); group 2, hazard ratio 1.18 (0.86 to 1.62), rate difference 1.06 (−1.77 to 3.89); group 3, hazard ratio 1.30 (0.52 to 3.26), rate difference 0.47 (−0.73 to 1.67); and group 4, hazard ratio 1.73 (1.30 to 2.29), rate difference 3.66 (1.74 to 5.59).

Conclusions The increase in rate of amputation with canagliflozin was small and most apparent on an absolute scale for adults aged 65 or older with baseline cardiovascular disease, resulting in a number needed to treat for an additional harmful outcome of 556 patients at six months (that is, 18 more amputations per 10 000 people who received canagliflozin). These results help to contextualize the risk of amputation with canagliflozin in routine care.

Introduction

Sodium glucose cotransporter 2 (SGLT2) inhibitors decrease plasma glucose by inhibiting its reabsorption at the proximal tubule and by lowering the renal threshold for glucose excretion.1 Canagliflozin reduces the risk of myocardial infarction, stroke, and cardiovascular mortality.2 Additional benefits of the drug include a reduction in the rate of hospital admission for heart failure and renal failure, and reductions in systolic blood pressure, weight, and proteinuria.23 SGLT2 inhibitors, however, are also associated with an increased risk of important adverse events (eg, diabetic ketoacidosis, urogenital infections).45 The CANVAS (CANagliflozin cardioVascular Assessment Study) Program also detected an increased risk of amputation with canagliflozin in comparison with placebo.2

CANVAS consisted of two randomized cardiovascular outcome trials that included adults with established cardiovascular disease or multiple risk factors for cardiovascular disease.2 Canagliflozin was associated with a nearly twofold increased risk of lower limb amputation compared with placebo (6.3 v 3.4 per 1000 person years). The increased risk of amputation was surprising, because it had not been reported in previous clinical trials of canagliflozin or other SGLT2 inhibitors.6 As the mean age of patients included in the CANVAS Program was 63 years, about 10 years older than patients in previous trials, the risk of amputation could possibly be confined to older adults.6 The increased risk of amputation in CANVAS might also be related to the higher baseline cardiovascular risk of the patients included compared with previous trials of canagliflozin.6

Since the results of CANVAS, many observational studies have quantified the rate of amputation with canagliflozin. Two studies, started by the manufacturers of canagliflozin, did not find a higher rate of amputation in analyses that focused on canagliflozin.78 Two other studies, using data from the insurance claims database MarketScan up until 2015, found an increased rate of amputation with SGLT2 inhibitors (most of which were canagliflozin), but because of the paucity of events the confidence intervals were wide9 and crossed 1.0 for one of the studies, allowing for a possible null effect.10 In all four studies, the average age of patients was about 55 and most patients had no baseline history of cardiovascular disease.

As age and cardiovascular disease are two of the strongest risk factors for amputation among adults with diabetes, it is important to assess the potentially increased risk of amputation with canagliflozin among older adults and patients at higher risk of cardiovascular disease.111213 We considered including other SGLT2 inhibitors but were underpowered to do so. Furthermore, canagliflozin was the most commonly dispensed SGLT2 inhibitor in the United States during the period of our study. In addition, after publication of the CANVAS Program, patients at higher risk of amputation could have been directed towards receiving empagliflozin or dapagliflozin because neither drug has been shown to be associated with an increased risk of amputation.1415 Thus we conducted an observational cohort study using three nationwide databases in the US with data up until 2017 to estimate the rate of lower limb amputation among patients newly prescribed canagliflozin, according to age and baseline cardiovascular risk.

Methods

Study population

We conducted a population based, new user, cohort study using three US healthcare claims databases: Optum Clinformatics Data Mart Database, IBM MarketScan, and Medicare fee-for-service (parts A/B/D). The databases contain deidentified longitudinal, individual level data on healthcare use, inpatient and outpatient diagnoses, diagnostic tests and procedures, outpatient laboratory results (available for about 40% of patients in Optum and 6% of patients in MarketScan), and pharmacy dispensing of drugs. MarketScan and Optum primarily include adults with employer based health plans. The average age of adults is generally higher in Optum than in MarketScan, because about 10% of adults in Optum have Medicare Advantage (a supplemental insurance plan for patients in Medicare).16 Medicare predominantly includes adults aged over 65 years. Collectively, these three databases include over 100 million people in the US.

We compared data for adults with diabetes mellitus type 2 newly prescribed canagliflozin or a glucagon-like peptide-1 (GLP-1) agonist between 29 March 2013 (date of approval of canagliflozin) and the last available data (Optum: 30 September 2017, MarketScan: 31 December 2017, Medicare: 31 December 2016). The CANVAS trial was published online in June 2017, and thus the data for the vast majority of patients included in our study predated that date.2 Patients with diabetes mellitus type 2 were identified using ICD-9 (international classification of diseases, ninth revision) and ICD-10 codes (appendix table 1). The cohort entry date was the date of the first prescription for canagliflozin or a GLP-1 agonist. New users of these drugs were defined as those without a previous prescription for an SGLT2 inhibitor or GLP-1 agonist in the preceding 180 days. GLP-1 agonists were chosen as the comparator because they are also a second line treatment for diabetes, have similar cardiovascular benefits, and have not been associated with an increased risk of amputation.1718

Patients prescribed both canagliflozin and a GLP-1 agonist on the cohort entry date were excluded. Patients with any of the following characteristics in the 180 days before cohort entry were also excluded: insufficient baseline healthcare data (that is, <180 days), human immunodeficiency virus, end stage renal disease, cancer, or type 1 diabetes. These characteristics were selected because they could be associated with directing drugs to a specific patient group. For example, some patients with type 1 diabetes in the US are prescribed SGLT2 inhibitors off label.19 Similar to the CANVAS Program, patients with a prior amputation were not excluded.

Cohort follow-up

Follow-up began on the day after cohort entry (date of first prescription) and continued until the end of the study, end of enrollment in a continuous health plan, occurrence of a study outcome, discontinuation of the initial drug (or switching to, or adding, the comparator drug), or death. A drug was considered to be discontinued if 60 days had elapsed after the expiration of the last prescription’s supply without the prescription being refilled.

Study outcome

The primary outcome was lower limb amputation requiring surgery based on an ICD-9/10 procedural code or a current procedural terminology code (appendix 2).720 These codes are commonly used in observational studies,789 and a validation study showed sensitivity above 94% and positive predictive value above 80%.21

Baseline covariates

All covariates were assessed during the 180 days before cohort entry, including the index date. Data were collected for each patient (table 1 and appendix 3) on the basis of diagnoses and procedures recorded during health encounters, including chronic medical conditions, diabetes severity, amputation risk, healthcare use, recent clinic appointments, drugs for treatment of diabetes and non-diabetes related drugs. These variables were selected a priori based on available literature, clinical experience, and expert opinion.222324

Table 1

Selected baseline patient characteristics after propensity score matching across three US databases. Data are number (%) unless otherwise specified

View this table:

Statistical analysis

We used propensity score matching to adjust for confounding. The probability of a prescription fill for canagliflozin versus a GLP-1 agonist was calculated through a multivariable logistic regression model, which contained all potential confounders at baseline except laboratory values—for example, hemoglobin A1c and creatinine, because these results were not available for all patients. A caliper of 0.05 on the propensity scale was used for matching with a 1:1 ratio. Covariate balance between the matched exposure groups was assessed using standardized differences. A standardized difference of 0.1 or less indicates negligible differences between groups.25

Within each database, separate propensity scores were estimated and used for 1:1 matching initiators of canagliflozin or a GLP-1 agonist in each of four mutually exclusive groups: group 1, patients aged less than 65 without baseline cardiovascular disease; group 2, patients aged less than 65 with baseline cardiovascular disease; group 3, patients aged 65 and older without baseline cardiovascular disease; group 4, patients aged 65 and older with baseline cardiovascular disease. Cardiovascular disease was defined as a diagnosis during the baseline period of one or more of coronary artery disease, stroke or transient ischemic attack, heart failure, peripheral vascular disease, or amputation.

After propensity score matching, we calculated the rate per 1000 person years of the primary outcome among exposure groups in each of the four groups of age and cardiovascular disease within each database. We also calculated rate differences per 1000 person years and 95% confidence intervals, and estimated hazard ratios and 95% confidence intervals, using proportional hazards models without further adjustments. Within each of the four groups of age and cardiovascular disease, hazard ratios and rate differences per 1000 person years from each database were then combined using a random effects meta-analysis that weighted studies by the inverse of their variance using the DerSimonian and Laird approach.26 Estimated variances for rates assumed a Poisson distribution. We evaluated the presence of effect measure modification of canagliflozin across 10 categories of age, baseline cardiovascular disease, and database on a relative and absolute scale using the Wald test for homogeneity (χ2 with nine degrees of freedom).27 This analysis allowed us to estimate the relative effect of cardiovascular disease and age on the rate of amputation. We provided both relative risk estimates and risk difference estimates to help contextualize the potential risk of amputation for both a population and an individual patient. Measurement of the risk in absolute terms is critical for a well informed benefit-risk assessment.28

To assess the ability of correctly reproducing a known association in our data, we also assessed the risk of hospital admission for heart failure as a positive control, because previous studies have shown a reduction in heart failure with SGLT2 inhibitors, but not with GLP-1 agonists.2202930 All analyses were conducted using the validated Aetion platform, version 3.1231 and R version 3.1.2.

Patient and public involvement

No patients were involved in planning the research question, outcome measures, study design, study implementation, or interpretation or writing up of the results.

Results

Study cohort and patient characteristics

From MarketScan, Optum, and Medicare we identified 496 642 people who satisfied study inclusion and exclusion criteria (appendix fig 1) before propensity score matching. Patient characteristics were well balanced after propensity score matching (table 1). Appendix table 3 shows complete patient characteristics within each database before and after propensity score matching. In general, patients who were prescribed a GLP-1 agonist were more likely to be female, have chronic kidney disease, or to have filled a prescription for insulin or a diuretic agent during the baseline period. Patients who were newly prescribed an SGLT2 inhibitor were less likely to have a diagnosis related to obesity or to have seen an endocrinologist, and more likely to have received a filled prescription for a dipeptidyl peptidase 4 inhibitor at baseline. The mean follow-up was approximately 275 days (appendix table 4). After propensity score matching, we identified 155 420 patients who were prescribed canagliflozin and 155 420 who were prescribed a GLP-1 agonist.

Patients aged less than 65

After propensity score matching, of patients under the age of 65 years without baseline cardiovascular disease, 98 adults who were prescribed a GLP-1 agonist had a lower limb amputation (1.55 per 1000 person years) compared with 117 adults prescribed canagliflozin (1.67 per 1000 person years; table 2). This result corresponded to a hazard ratio of 1.09 (95% confidence interval 0.83 to 1.43, I2=0%; fig 1) and to an absolute rate difference of 0.12 per 1000 person years (95% confidence interval −0.31 to 0.55; fig 2). Appendix table 5 shows the rates of amputation for patients from each database. For patients younger than 65 years with baseline cardiovascular disease, 69 adults prescribed a GLP-1 agonist had a lower limb amputation (8.57 per 1000 person years) compared with 87 adults prescribed canagliflozin (9.74 per 1000 years). This result corresponded to a hazard ratio of 1.18 (0.86 to 1.62, I2=0%; fig 1) and to an absolute rate difference of 1.06 per 1000 person years (−1.77 to 3.89; fig 2).

Table 2

Propensity score matched rate of amputation, hazard ratios, and rate differences stratified by age and baseline cardiovascular disease

View this table:
Fig 1
Fig 1

Forest plot for propensity score matched rate of amputation for adults younger than 65 without cardiovascular disease, younger than 65 with cardiovascular disease, aged 65 and older without cardiovascular disease, and aged 65 and older with cardiovascular disease. GLP-1=glucagon like peptide-1

Fig 2
Fig 2

Forest plot for propensity score matched rate difference of amputation for adults younger than 65 without cardiovascular disease, younger than 65 with cardiovascular disease, aged 65 and older without cardiovascular disease, and aged 65 and older with cardiovascular disease. GLP-1=glucagon like peptide-1

Patients aged 65 and older

Among patients aged 65 and older without baseline cardiovascular disease, 53 adults who were prescribed a GLP-1 agonist had a lower limb amputation (1.61 per 1000 person years) compared with 81 adults prescribed canagliflozin (2.34 per 1000 person years). This result corresponded to a hazard ratio of 1.30 (95% confidence interval 0.52 to 3.26, I2=68%; fig 1) and to an absolute rate difference of 0.47 (−0.73 to 1.67; fig 2) per 1000 person years. For patients aged 65 and older with baseline cardiovascular disease, 74 adults prescribed a GLP-1 agonist had a lower limb amputation (5.46 per 1000 person years) compared with 132 adults prescribed canagliflozin (9.32 per 1000 person years). This result corresponded to a hazard ratio of 1.73 (1.30 to 2.29, I2=0%; fig 1) and to an absolute rate difference of 3.66 per 1000 person years (95% CI 1.74 to 5.59; fig 2). Figure 3 shows Kaplan-Meier plots for amputation for adults younger and older than 65 and with and without cardiovascular disease. The evidence for heterogeneity across the 10 groups formed by age, baseline cardiovascular disease, and database, was modest on a relative scale, with overall test of heterogeneity not reaching significance (P=0.14); evidence for significant heterogeneity was shown on an absolute scale (P=0.01). These data suggest that the combination of both factors (that is, age and cardiovascular disease) meaningfully increased the absolute rate of amputation.

Fig 3
Fig 3

Kaplan-Meier plot for amputation after propensity score matching for adults (A) younger than 65 years without cardiovascular disease, (B) younger than 65 years with cardiovascular disease, (C) aged 65 and older without cardiovascular disease, and (D) aged 65 and older with cardiovascular disease. GLP-1=glucagon like peptide-1

Validation against a known causal association

The propensity score matched rate of hospital admission due to heart failure was lower for patients prescribed canagliflozin than for those receiving GLP-1 agonists across the four groups (appendix table 6). For example, among patients under 65 without baseline cardiovascular disease, the hazard ratio was 0.50 (95% confidence interval 0.29 to 0.88) for canagliflozin compared with a GLP-1 agonist.

Discussion

In this longitudinal study of over 300 000 propensity score matched adults with type 2 diabetes mellitus given routine care, an increased rate of amputation associated with canagliflozin, compared with a GLP-1 agonist, was small. The rate was most apparent on an absolute scale among adults aged over 65 with baseline cardiovascular disease, resulting in nearly four more amputations in 1000 person years. This observation, in addition to the rate of amputation calculated in the other three groups included in our study, which resulted in 0.1 to 1.1 additional amputations in 1000 person years, 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.

Assessing the incremental risk of amputation associated with the use of new drugs for diabetes is important, because adults with diabetes have a markedly higher rate of amputation than adults without diabetes.3233 Lower limb amputation is also associated with considerable disability, morbidity, and mortality.3435 For example, in adults over the age of 65, amputation is associated with a one year mortality of about 50%.3435

We observed a similar rate of amputation for adults aged less than 65 prescribed canagliflozin or a GLP-1 agonist, regardless of baseline cardiovascular disease, which is in agreement with previous real world studies of canagliflozin.7810 It is unlikely that our findings are explained by changes in prescribing of canagliflozin on the basis of the potential risk of amputation, because almost all data from our study preceded publication of the CANVAS Program. Unlike CANVAS, we were unable to include a placebo group because we used data from routine care. We could have compared adults with diabetes who were prescribed canagliflozin with adults with diabetes who did not receive the drug. Previous research, however, has shown that a non-user comparator group can lead to several forms of bias, including confounding and immortal time bias.36 Our findings are also consistent with the initial clinical trials of canagliflozin, which typically included patients aged less than 65 and in whom baseline cardiovascular disease was uncommon.6

The higher rate of amputation with canagliflozin in our study was most apparent among adults aged 65 or older who had baseline cardiovascular disease. This rate is in line with a recent observational study of 12 629 veterans from the Veterans Affairs database (mean age 66) prescribed an SGLT2 (58% were prescribed canagliflozin) compared with adults not prescribed an SGLT2 (odds ratio 1.99, 95% confidence interval 1.12 to 3.51).20 The rate of amputation we observed among adults aged 65 and older with baseline cardiovascular disease corresponded to a number needed to treat for an additional harmful outcome of 556 (95% confidence interval 301 to 3596) at six months, calculated based on the Altman and Andersen approach.37 Thus 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).

Our results are similar to those of the CANVAS Program, but they differ from the recently published CREDENCE trial (canagliflozin and renal outcomes in type 2 diabetes and nephropathy).3 The CREDENCE trial randomized 4401 adults with diabetes who had albuminuric chronic renal failure to either canagliflozin or placebo and observed a similar rate of amputation with canagliflozin and placebo (hazard ratio 1.11, 95% confidence interval 0.70 to 1.37).3 In May 2016, however, two years after the start of the CREDENCE trial, an amendment was issued that “asked investigators to examine patients’ feet at each trial visit and temporarily interrupt the assigned treatment in patients with any active condition that might lead to amputation.”3 Although this was necessary to prevent potential amputation with canagliflozin, it could also have driven the null finding. Another explanation for the lack of an increased risk of amputation with canagliflozin could be related to baseline cardiovascular risk. For example, only half of the included patients in the CREDENCE trial had cardiovascular disease at baseline compared with two thirds in the CANVAS Program.23

Established cardiovascular disease is one of the strongest risk factors for amputation among adults with diabetes.113338 In our study, the overall rate of lower limb amputation was highest among patients prescribed canagliflozin with baseline cardiovascular disease (age <65 years: 9.74 per 1000 person years, age ≥65 years: 9.32 per 1000 person years). By contrast, the overall rate of amputation for adults without established cardiovascular disease prescribed canagliflozin was lower (age <65 years: 1.67 per 1000 person years, age ≥65 years: 2.34 per 1000 person years).7810 Taken together, these facts suggest that established cardiovascular disease might be a stronger predictor for amputation than older age.

The cardiovascular outcome trials for empagliflozin and dapagliflozin found no increased risk of amputation compared with placebo.1429 Some have speculated that unique pharmacologic properties of canagliflozin could explain the increased risk of amputation that has not been seen for empagliflozin or dapagliflozin.2939 One hypothesis is that canagliflozin has a more potent diuretic effect than empagliflozin or dapagliflozin, and the resultant hemoconcentration and hyperviscosity could increase the risk of peripheral tissue ischemia.39 This mechanism has also been reported to explain the increased rate of amputations seen with some diuretic agents.40 In vitro studies have shown that canagliflozin, but not dapagliflozin or empagliflozin, inhibits both glutamate dehydrogenase and complex I of the mitochondrial electron transport chain.41 This dual inhibition has been shown to cause intracellular accumulation of various amino acids which can induce cytotoxicity.41 It is unknown if either of these purported mechanisms explains the observed increased risk or if there is another mechanism yet to be identified.

Limitations

A limitation of our study is that it was not randomized, and thus is prone to residual confounding. Furthermore, our study lacked an adequate sample size to individually analyze other SGLT2 inhibitors (that is, empagliflozin, dapagliflozin). A recent cohort study identified a higher rate of amputation among adults prescribed empagliflozin or dapagliflozin (mean age 61 years) than those prescribed GLP-1 agonists, but few people receiving an SGLT2 inhibitor had an amputation (n=27), as expressed in the study’s wide confidence intervals (hazard ratio 2.32, 95% confidence interval 1.37 to 3.91).42 Another limitation is that we selected GLP-1 agonists rather than another class of oral drugs for diabetes (eg, dipeptidyl peptidase 4 (DPP4) inhibitors). Previous work shows that patients prescribed SGLT2 inhibitors and GLP-1 agonists are of similar age, whereas adults prescribed a DPP4 inhibitor tend to be older and are more likely to have reduced renal function.4344 Furthermore, both SGLT2 inhibitors and GLP-1 agonists have been shown to reduce the risk of cardiovascular events in randomized controlled trials, and thus in comparison with DPP4 inhibitors, it is expected that these two classes of drugs are more likely to be prescribed to patients with similar baseline cardiovascular risk. This choice of prescription is supported by the strong similarity between these two groups of patients (that is, those receiving GLP-1 agonists compared with SGLT2 inhibitors) before propensity score matching.

An additional limitation of our study is that we lacked complete data on the severity of the diabetes for all patients (eg, duration of diabetes, hemoglobin A1c) and other risk factors for amputation (eg, body mass index, duration of smoking). A recent study showed that propensity score matching of other diabetes related severity and comorbidity variables can achieve balance for such unmeasured characteristics, including duration of diabetes, body mass index, and smoking.45 We do not expect that these differences would be large enough to affect the risk of amputation because the comparator drug treatments (that is, GLP-1 agonists) are prescribed to patients with similar baseline characteristics. Furthermore, we stratified by variables strongly associated with amputation (eg, older age) and by cardiovascular disease, which is colinear with diabetes severity. Another important limitation of our study is that tests for interaction are low powered and we cannot perfectly separate cardiovascular risk from older age since the two are highly positively correlated.46

Conclusion and future implications

Our results suggest that the increased risk of amputation with canagliflozin is small and most apparent on an absolute scale among adults aged 65 or older with baseline cardiovascular disease, resulting in nearly four more amputations in 1000 person years with canagliflozin than with a GLP-1 agonist, corresponding to a number needed to treat for an additional harmful outcome of 556 patients at six months. These findings help to contextualize the risk of amputation in routine care and can help patient-physician decision making before prescribing canagliflozin.

What is already known on this topic

  • The cardiovascular outcome trial for canagliflozin identified a nearly twofold increased risk of lower limb amputation with canagliflozin than with placebo

  • The mean age of patients included in the CANVAS Program was 63 years, about 10 years older than patients in previous trials, suggesting that the risk of amputation could be confined to older adults

  • The increased risk of amputation in CANVAS could also be related to the higher baseline cardiovascular risk of patients included in that trial in comparison with previous trials of canagliflozin

What this study adds

  • This study included 310 840 propensity score matched adults who were newly prescribed canagliflozin or a glucagon-like peptide-1 (GLP-1) agonist

  • The increased risk of amputation with canagliflozin was most apparent among older adults who had cardiovascular disease at baseline

  • In this population the hazard ratio was 1.73 (95% confidence interval 1.30 to 2.29), corresponding to a rate difference of 3.66 (95% confidence interval 1.74 to 5.59) per 1000 person years compared with GLP-1 agonists

Footnotes

  • Contributors: All authors took part in study concept, design, acquisition of data, analysis/interpretation of data, and critical revision of the manuscript. MF drafted the original version of the manuscript. MF, EP, and RJG performed the statistical analysis. MF and EP are guarantors for the data. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding: The study was funded by the Division of Pharmacoepidemiology and Pharmacoeconomics and the study team had full control over all aspects of the study design, analysis, and write-up.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: support from the Division of Pharmacoepidemiology and Pharmacoeconomics for the submitted; MF received funding from the Eliot Phillipson Clinician-Scientist Training Program at the University of Toronto and Canadian Institutes of Health Research through the Frederick Banting and Charles Best Canada Graduate Scholarship. EP is supported by a career development grant K08AG055670 from the National Institute on Ageing. She is investigator on grants to Brigham and Women’s Hospital from Boehringer Ingelheim and GlaxoSmithKline, not directly related to the topic of this manuscript. SS is consultant to WHISCON (World Health Information Science Consultants), and to Aetion, a software manufacturer of which he also owns equity. He is principal investigator of investigator initiated grants to Brigham and Women’s Hospital from Genentech, Bayer, and Boehringer Ingelheim not directly related to the topic of this manuscript. RJG reports grants from Pfizer, Novartis, and Kowa outside the submitted work. BME reports grant support or consulting for Amarin, Amgen, Merck, Novartis, and Roche Diagnostics, National Heart, Lung, and Blood Institute, National Institute of Diabetes and Digestive and Kidney Diseases, and the US Food and Drug Administration. SCK has received research grants to Brigham and Women’s Hospital from Pfizer, Bristol-Myers Squibb, AstraZeneca, Roche, and Merck for unrelated topics.

  • Ethical approval: The institutional review board at Brigham and Women’s Hospital provided ethics approval and valid data use agreements were in place.

  • Data sharing: The databases used in the study can be accessed through a license with MarketScan, Optum, and Medicare. No additional data are available from the authors.

  • The lead author affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

  • Dissemination to participants and related patient and public communities: The data were not available to outside parties.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

http://creativecommons.org/licenses/by-nc/4.0/

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

References

View Abstract