Therapeutics Letter 107 explores the findings of the EMP-REG trial. Conclusions: The EMPA-REG OUTCOME Trial tested the addition of empagliflozin to a ‘standard of care’ for T2DM whose impact on clinically important outcomes is currently unknown. It is uncertain whether the reduction in mortality and serious adverse events in the EMPA-REG OUTCOME Trial is attributable to empagliflozin or to less use of other glucose-lowering therapies. The results of this trial are not applicable to people with T2DM in other clinical settings. Until there is a body of evidence informed by large, independently conducted comparative effectiveness trials of different therapeutic strategies, we will not know the optimal treatment of T2DM at various stages of the diagnosis.

The EMPA-REG OUTCOME Trial tested adding empagliflozin to ‘standard of care’

In this trial, 7028 T2DM patients with established cardiovascular disease were randomized to 1 of 3 arms: empagliflozin 10 mg or empagliflozin 25 mg or placebo and were followed for a median of 3.1 years.³ Participants were eligible if their glycated haemoglobin (HbA1c) was 7.0% to 10.0% (mean 8.1%). Other parameters: mean age 63, 72% white, 72% male, mean BMI 31 kg/m², 95% taking antihypertensives, 81% taking lipid-lowering drugs, and 83% taking antiplatelet medications. Most had a diagnosis of T2DM for >5 years, more than half had a diagnosis for >10 years. At baseline 98% of participants were receiving other glucose-lowering medications; 68% were receiving 2 or more. Metformin, insulin and sulfonylureas were prescribed to 74%, 48%, and 43% of participants, respectively. The net health effect of the various glucose-lowering drugs and drug combinations prescribed to participants at baseline and throughout the trial is not known.⁵

The results using our usual outcome hierarchy are shown in Table 1. The 2 empagliflozin arms have been combined; the outcomes were similar for the 2 doses.

Table 1

The EMPA-REG OUTCOME Trial Outcomes

If this trial had been conducted in a way that empagliflozin was the only difference between the groups, these results would suggest that empagliflozin causes a net health benefit in people with T2DM and a history of cardiovascular disease. Unfortunately, empagliflozin was not the only difference between the groups. During the trial, HbA1c was not blinded and investigators could escalate medications in an effort to achieve a glucose target ≤6.5–7.0% in accordance with aggressive ‘standards of care’. As a result, other glucose-lowering medications were added more frequently and at higher doses in the placebo group^3,7 (see Table 2).

Table 2

The EMPA-REG OUTCOME Trial Medication changes after randomization

Interpretation

There are thus at least 3 possible interpretations of the EMPA-REG OUTCOME Trial:

1. Empagliflozin decreases mortality and serious adverse events when added to ‘standard of care’.
2. The more aggressive use of other glucose-lowering medications in the placebo group increases mortality and serious adverse events.
3. A combination of 1 and 2.

After a detailed examination of the published trial³, the U.S. FDA review⁷, the European Medicines Agency (EMA) review⁸, and the German Institute for Quality and Efficiency in Health Care (IQWiG) review⁹, we are not confident in explanation #1. In support of explanation #2 there are 2 RCTs that have shown that more intensive therapy in T2DM increases total mortality and cardiovascular mortality.^10,11 Whether these findings are attributable to the pursuit of an intensive HbA1c target or to the use of any specific drug or drug-combination remains uncertain.

We are not alone in not accepting the results of this trial. In June 2016, a 23-member FDA advisory committee voted on whether, based on this single trial, the company could claim that empagliflozin reduces cardiovascular mortality. The vote was 12 for and 11 against.^12,13

Did empagliflozin cause harm?

Harms were increased in those taking empagliflozin in the EMPA-REG OUTCOME Trial (Table 3). The increase in genital infections in both men and women means that during a 3 year time period, 1 in 29 men and 1 in 14 women will have their quality of life adversely affected by a genital infection.

Table 3

The EMPA-REG OUTCOME Trial Harms

Other reasons for scepticism

The FDA review of the EMPA-REG OUTCOME Trial rejected the manufacturer’s claim that empagliflozin reduces the risk of heart failure and nephropathy.⁷ In addition, analyses of outcomes by geography identified unexplained regional differences: the magnitude of effect of empagliflozin on mortality was less in North America and Europe compared to Latin America and Asia.⁶ Another independent drug bulletin has critically appraised this trial and identified these and many other concerns.¹⁴ It should also be clear that this trial tells us nothing about the use of empagliflozin in other T2DM clinical settings.

Conclusions

• The EMPA-REG OUTCOME Trial tested the addition of empagliflozin to a ‘standard of care’ for T2DM whose impact on clinically important outcomes is currently unknown.
• It is uncertain whether the reduction in mortality and serious adverse events in the EMPA-REG OUTCOME Trial is attributable to empagliflozin or to less use of other glucose-lowering therapies.
• The results of this trial are not applicable to people with T2DM in other clinical settings.
• Until there is a body of evidence informed by large, independently conducted comparative effectiveness trials of different therapeutic strategies, we will not know the optimal treatment of T2DM at various stages of the diagnosis.

References

1.

Health Canada. Product Monograph. JARDIANCE empagliflozin tablets. Drug Product Database. August 25, 2017; [Internet] https:​//health-products​.canada.ca/dpd-bdpp/index-eng.jsp

2.

Health Canada. Summary Basis of Decision. JARDIANCE. Drug and Health Product Register. August 27, 2015; [Internet] https://hpr-rps​.hres​.ca/reg-content/summary-basis-decision​.php

3.

Zinman B, Wanner C, Lachin JM, et al. Empagliflozin, Cardiovascular Outcomes, and Mortality in Type 2 Diabetes. N Engl J Med 2015; 373(22):2117–28. DOI:10.1056/NEJMoa1504720 [PubMed: 26378978] [CrossRef]

4.

U.S. Food & Drug Administration. Guidance for Industry. Diabetes Mellitus – Evaluating Cardiovascular Risk in New Antidiabetic Risk in New Antidiabetic Therapies to Treat Type 2 Diabetes. December 2008; [Internet] http://www​.fda.gov/downloads​/drugs/guidancecomplianceregulatoryinformation​/guidances/ucm071627.pdf

5.

Maruther NM, Tseng E, Hutfless S, et al. Diabetes medications as monotherapy or metformin-based combination therapy for type 2 diabetes. A systematic review and meta-analysis. Ann Intern Med 2016; 164(11):740–51. DOI:10.7326/M15-2650 [PubMed: 27088241] [CrossRef]

6.

Boehringer Ingelheim. EMPA-REG OUTCOME Trial. U.S. Food & Drug Administration Endocrinologic and Metabolic Drugs Advisory Committee Briefing Document. NDA 204629 / NDA 206111. May 19, 2016; [Internet] https://www​.fda.gov/downloads​/AdvisoryCommittees​/CommitteesMeetingMaterials​/Drugs​/EndocrinologicandMetabolicDrugsAdvisoryCommittee​/UCM508423.pdf

7.

U.S. Food & Drug Administration. 2016 Meeting materials, Endocrinologic and Metabolic Drugs Advisory Committee. June 28, 2016; [Internet] https://www​.fda.gov/AdvisoryCommittees​/CommitteesMeetingMaterials​/Drugs/EndocrinologicandMetabolicDrugsAdvisoryCommittee/ucm491062.htm

8.

European Medicines Agency. Committee for Medicinal Products for Human Use. Jardiance (empagliflozin) Assessment report. EMA/11728/2017. Procedure No. EMEA/H/C/002677/II/0014. December 15, 2016; [Internet] http://www​.ema.europa​.eu/docs/en_GB/document_library​/EPAR_-_Assessment​_Report_-_Variation​/human/002677/WC500224837.pdf

The draft of this Therapeutics Letter was submitted for review to 75 experts and primary care physicians in order to correct any inaccuracies and to ensure that the information is concise and relevant to clinicians.

The Therapeutics Initiative is funded by the BC Ministry of Health through a grant to the University of BC. The Therapeutics Initiative provides evidence-based advice about drug therapy, and is not responsible for formulating or adjudicating provincial drug policies.