Quality Measure Attainment After Add-on Therapy of Both Saxagliptin and Dapagliflozin to Metformin Versus Single Add-On of Saxagliptin or Dapagliflozin

Journal of Clinical Outcomes Management. 2016 September;SEPTEMBER 2016, VOL. 23, NO. 9:

September 5, 2016|Journal of Clinical Outcomes Management

Lawrence Blonde, MD;John J. Sheehan, PhD;Yu Chen Barrett, PhD;Ricardo Garcia-Sanchez, MD

From the Ochsner Diabetes Clinical Research Unit, Frank Riddick Diabetes Institute, Department of Endocrinology, Ochsner Medical Center, New Orleans, LA (Dr. Blonde), and AstraZeneca, Gaithersburg, MD (Drs. Sheehan, Barrett, and Garcia-Sanchez).

Abstract

Objective: To evaluate diabetes care quality measure attainment, specifically, blood glucose and blood pressure (BP) control, with saxagliptin, a dipeptidyl peptidase-4 inhibitor, and dapagliflozin, a sodium-glucose cotransporter-2 inhibitor, added singly or as dual add-on therapy in patients with type 2 diabetes inadequately controlled with metformin alone.
Methods: Analysis of a phase 3, randomized, double-blind, active-controlled, parallel-group trial was conducted. Patients were randomized 1:1:1 to receive saxagliptin 5 mg/d plus dapagliflozin 10 mg/d, saxagliptin 5 mg/d, or dapagliflozin 10 mg/d as add-on to metformin 1500 to 2000 mg/d. Assessments included attainment of individual and composite glycated hemoglobin (A1C) and BP measures at 24 weeks of treatment.
Results: Compared with single add-on saxagliptin or dapagliflozin, dual add-on saxagliptin plus dapagliflozin to metformin was associated with significantly more patients attaining the individual quality measures of A1C < 7% and A1C < 8%. Similarly, dual add-on saxagliptin plus dapagliflozin was associated with significantly more patients attaining the composite quality measures A1C < 7% and BP < 140/90 mm Hg and A1C < 8% and BP < 140/90 mmHg (vs saxagliptin plus metformin).
Conclusion: Dual add-on saxagliptin plus dapagliflozin to metformin was associated with a higher proportion of patients achieving glycemic and BP quality measures compared with single add-on saxagliptin or dapagliflozin.

Assessment of performance is a focus of many health care organizations as a means to evaluate and improve the quality of health care. Standardized performance measures have been developed to improve quality of care as well as to allow for comparative assessment of health plans and to support pay for performance models [1]. A widely used set of performance measures is the Healthcare Effectiveness Data and Information Set or HEDIS [2,3], measures that are maintained by the National Committee for Quality Assurance [4,5] and used by most US health plans [6].

Type 2 diabetes (T2D) is a focus of quality measure assessment and performance improvement because of its high prevalence, substantial personal and economic impact on society, high morbidity and mortality, and because it is a condition that requires coordinated care. Important outcome measures for diabetes include blood glucose control and blood pressure (BP) control. HEDIS measures for T2D include a glycated hemoglobin (A1C) > 9%, indicating poor glucose control, < 8%, indicating good control, and < 7%, a more stringent measure of good glycemic control. The HEDIS measure for BP in T2D is < 140/90 mm Hg, which is considered good BP control. All of these HEDIS measures are currently or were previously (A1C < 7%) endorsed by the National Quality Forum [1,7–10]. Endorsement of a quality measure by the NQF indicates that the measure has been thoroughly evaluated, meets specific criteria, and is based on recognized standards of care grounded in evidence-based medicine [1].

A number of oral agents are utilized in the treatment of diabetes. Saxagliptin, an oral dipeptidyl peptidase-4 (DPP-4) inhibitor, and dapagliflozin, an oral sodium-glucose cotransporter-2 (SGLT-2) inhibitor, are indicated as adjuncts to diet and exercise in adults with T2D [11,12]. Saxagliptin inhibits DPP-4, and thereby reduces fasting and postprandial glucose concentrations by preventing degradation of the incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide [13]. Dapagliflozin reduces blood glucose concentrations by inhibiting glucose reabsorption in the proximal tubule of the kidney, which results in enhanced urinary glucose excretion [14]. Because their mechanisms of action are glucose-dependent, both saxagliptin and dapagliflozin have a low intrinsic potential to cause hypoglycemia [13,14]. In a randomized, double-blind study of patients with T2D inadequately controlled with metformin, Rosenstock et al assessed the efficacy and safety of dual add-on of saxagliptin plus dapagliflozin versus saxagliptin and dapagliflozin added on alone (ClinicalTrials.gov identifier, NCT01606007) [15]. The dual add-on therapy resulted in a greater adjusted mean reduction from baseline in A1C at week 24 (–1.47%) compared with either saxagliptin (–0.88%) or dapagliflozin (–1.20%) alone added to metformin; the difference for dual add-on saxagliptin plus dapagliflozin to metformin vs. single add-on saxagliptin and single add-on dapagliflozin was –0.59% (P < 0.001) and –0.27% (P = 0.0166), respectively. The incidence of adverse events was similar across the 3 treatment groups, and hypo-glycemia was infrequent (1%), with no reports of severe hypoglycemia events (symptomatic events with glucose ≤ 54 mg/dL requiring assistance).

In this paper, we assess the attainment of diabetes quality measures among patients in this study, specifically, measures of glycemic and BP control.

Methods

Study Design and Patients

This was a post hoc analysis of a phase 3, multicenter, randomized, double-blind, active-controlled, parallel-group, 24-week study. Details of the study design, inclusion/exclusion criteria, and primary results have been previously reported [15]. In brief, men and women aged ≥ 18 years with T2D poorly controlled (A1C 8.0%–12.0%) with metformin monotherapy were randomized 1:1:1 to receive saxagliptin 5 mg/d and dapagliflozin 10 mg/d, saxagliptin 5 mg/d and placebo, or dapagliflozin 10 mg/d and placebo on a background of metformin extended release 1500 to 2000 mg/d (Figure 1). Patients were required to be on stable metformin (≥ 1500 mg/d) for ≥ 8 weeks before screening and to have a C-peptide concentration ≥ 1.0 ng/mL and a body mass index ≤ 45.0 kg/m². The trial was designed and monitored in accordance with the ethical principles of Good Clinical Practice as defined by the International Conference on Harmonisation and the Declaration of Helsinki. Institutional review boards or ethics committees at each study site approved the protocol, and all patients gave written informed consent.

Quality Measure Assessment

Individual measures assessed included the proportion of patients with A1C < 7%, A1C < 8%, A1C > 9%, and BP < 140/90 mm Hg. Composite measures assessed includedthe proportion of patients with A1C < 7% and BP < 140/90 mm Hg and the proportion of patients with A1C < 8% and BP < 140/90 mm Hg.

Antihypertensive or cholesterol-lowering medication use was not controlled for in this study. Patients were maintained on their prescribed dosing regimen for antihypertensive and cholesterol-lowering medications, with adjustments as needed per the standard of care for their diagnosis. Treatment outcomes for A1C < 7%, < 8%, or > 9% were prespecified. The BP treatment outcome was also prespecified per the statistical analysis plan; however, a change to the HEDIS quality measure treatment outcome for BP during the clinical study resulted in this analysis being no longer relevant. Therefore, analyses of the currently endorsed quality measures for BP were conducted post hoc. Quality measure assessments for A1C and BP treatment outcomes were conducted using data from the 24-week, double-blind treatment period.

Statistical Analysis

P values for the differences in proportion of patients with individual treatment outcomes and composite treatment outcomes with saxagliptin plus dapagliflozin plus metformin versus saxagliptin plus metformin or dapagliflozin plus metformin were calculated using Fisher’s exact test. The numerator and denominator for each percentage are the number of responders and the number of patients with non-missing values in the treatment group at the corresponding baseline category, respectively, and are not corrected for baseline A1C. Because some patients experienced improvement in A1C during the lead-in period and could have already been at treatment goal at baseline, a sensitivity analysis excluding these patients was completed. Results are presented for the total number of patients with non-missing values in the treatment group, as well as patients with non-missing values in the treatment group who did not meet quality measure criteria at baseline. The number needed to treat (NNT) was calculated for all comparisons reaching statistical significance.

References