Cost and clinical impact of a nonmedical DPP-4 inhibitor switch in patients with diabetes.

BACKGROUND: Nonmedical formulary switches (NMFS) routinely occur in managed health care plans and involve changing preferred medications for reasons outside of clinical considerations. The cost implications of NMFS are infrequently published and the clinical outcomes rarely assessed. OBJECTIVE: To assess the real-world clinical and cost implications of an NMFS involving sitagliptin and linagliptin. METHODS: An NMFS was made to the Geisinger Health Plan (GHP) commercial, health care reform, and Medicaid formularies on February 1, 2018, involving a change in preferred medication from sitagliptin to linagliptin. Claims data from GHP and clinical information from electronic health records of the Geisinger Health System were used to evaluate the cost and clinical impact of this change. Patients aged 18 years or older who were continuously enrolled in a GHP commercial, health care reform, or Medicaid plan throughout the entire study period and had at least 1 fill for sitagliptin during the preswitch phase were included in the study. We investigated the differences in various clinical and economic outcomes from pre- to postswitch among those who switched and remained adherent to the new preferred therapy throughout the 12-month postperiod ("linagliptin switch" group) and patients who did not ("other switch" group). Clinical outcomes included all-cause hospitalization, diabetes-related hospitalization, and glycosylated hemoglobin (HbA1c), while economic measures included changes in per member per month (PMPM) spending. The negative binomial regression model was used to estimate utilization counts. A generalized linear model with a log link and gamma distribution was used to analyze cost data. RESULTS: 1,203 patients met the inclusion criteria. Of these, 501 (41.6%) individuals switched to and remained at least 80% adherent to linagliptin in the postperiod, while 702 (58.4%) did not. No difference between groups was found when comparing the pre- to postswitch change in all-cause hospitalization (incidence rate ratio (IRR) = 1.46, 95% CI = 0.66-3.23, P = 0.3436) or diabetes-related hospitalization (IRR = 1.39, 95% CI = 0.62-3.10, P = 0.4203). Additionally, no difference was found between groups regarding the change in HbA1c 12-month postswitch compared with baseline (difference between groups = -0.10%, 95% CI = -0.39%-0.19%, P = 0.4962). Total PMPM spending was 43% higher in the other switch group compared with the linagliptin switch group (IRR = 1.43, 95% CI = 1.25-1.63, P < 0.0001). This trend was driven by 92% higher medical PMPM spending in the other switch group compared with the linagliptin switch group (IRR = 1.92, 95% CI = 1.58-2.33, P < 0.0001) but was offset by 12% lower pharmacy PMPM spending in the other switch group (IRR = 0.88, 95% CI = 0.82-0.95, P = 0.0009). CONCLUSIONS: An NMFS from sitagliptin to linagliptin resulted in overall health plan savings with no significant changes in health outcomes. DISCLOSURES: Funding for this study was provided by Geisinger Health System, which had no role in the study outside of a final review of the submitted manuscript. Johns and Gionfriddo are Geisinger employees. The authors report no financial conflicts of interest.

Strong Modulation of Optical Properties in Black Phosphorus through Strain-Engineered Rippling.

Controlling the bandgap through local-strain engineering is an exciting avenue for tailoring optoelectronic materials. Two-dimensional crystals are particularly suited for this purpose because they can withstand unprecedented nonhomogeneous deformations before rupture; one can literally bend them and fold them up almost like a piece of paper. Here, we study multilayer black phosphorus sheets subjected to periodic stress to modulate their optoelectronic properties. We find a remarkable shift of the optical absorption band-edge of up to ∼0.7 eV between the regions under tensile and compressive stress, greatly exceeding the strain tunability reported for transition metal dichalcogenides. This observation is supported by theoretical models that also predict that this periodic stress modulation can yield to quantum confinement of carriers at low temperatures. The possibility of generating large strain-induced variations in the local density of charge carriers opens the door for a variety of applications including photovoltaics, quantum optics, and two-dimensional optoelectronic devices.

Topological Defects in Topological Insulators and Bound States at Topological Superconductor Vortices.

The scattering of Dirac electrons by topological defects could be one of the most relevant sources of resistance in graphene and at the boundary surfaces of a three-dimensional topological insulator (3D TI). In the long wavelength, continuous limit of the Dirac equation, the topological defect can be described as a distortion of the metric in curved space, which can be accounted for by a rotation of the Gamma matrices and by a spin connection inherited with the curvature. These features modify the scattering properties of the carriers. We discuss the self-energy of defect formation with this approach and the electron cross-section for intra-valley scattering at an edge dislocation in graphene, including corrections coming from the local stress. The cross-section contribution to the resistivity, ρ, is derived within the Boltzmann theory of transport. On the same lines, we discuss the scattering of a screw dislocation in a two-band 3D TI, like Bi1-xSbx, and we present the analytical simplified form of the wavefunction for gapless helical states bound at the defect. When a 3D TI is sandwiched between two even-parity superconductors, Dirac boundary states acquire superconductive correlations by proximity. In the presence of a magnetic vortex piercing the heterostructure, two Majorana states are localized at the two interfaces and bound to the vortex core. They have a half integer total angular momentum each, to match with the unitary orbital angular momentum of the vortex charge.