Evaluation of longer- vs short-term use of patiromer on health care resource utilization in the patiromer longer-term use evaluation (VALUE) study.

BACKGROUND: Studies suggest that continuous long-term use of patiromer by patients with hyperkalemia is associated with less health care resource utilization compared with not using potassium binders. OBJECTIVE: To retrospectively evaluate health care resource utilization and costs with longer-term adherent vs short-term use of patiromer. METHODS: Time-restricted extracts from Optum's de-identified Clinformatics® Data Mart Database (CDM; January 2016-May 2019) and Symphony Health (SHA; January 2016-September 2018) deidentified databases were analyzed. Both include participants enrolled in commercial and privatized public insurance programs (SHA includes some government programs). Both integrate health care claims data from medical and pharmacy claims. Patients aged 18 years or older with hyperkalemia and an index patiromer prescription were selected. Patiromer use was identified as short-term (<2 months) and any fill quantity or adherent longer-term with claims for at least 2 consecutive months and fill quantities of at least 80% of the total days. Groups were matched on multiple categorical covariates to control for demographic variables, baseline characteristics, and markers of disease severity. Random sampling without replacement was performed 50 times to identify 50 sets of patients matched from the short-term cohort to the longer-term cohort. Health care costs/charges and encounters were compared for a 6-month post-index period using t-tests. RESULTS: Of the CDM patients, 1,267 (40.2%) vs 1,887 (59.8%) and of the SHA patients, 2,234 (35.1%) vs 4,132 (64.9%) experienced longer-term vs short-term patiromer use, respectively. Patient sampling selected 242 and 485 patient-matched pairs from CDM and SHA databases, respectively. At 6 months post-index in longer-term vs short-term patiromer groups (P < 0.0001 for all differences shown), respective mean medical and prescription costs/charges were $42,000 vs $54,311 (-$12,311) and $6,816 vs $4,786 (+$2,030), respectively, for CDM patients and $75,147 vs $84,414 (-$9,267) and $4,689 vs $3,736 (+$953) for SHA patients. In the CDM database, medical costs were lower for longer-term vs short-term cohorts for end-stage renal disease services charges ($10,342 vs $14,976 [-$4,634]), inpatient charges ($15,789 vs $21,473 [-$5,684]), and office visit charges ($10,152 vs $13,152 [-$3,000]). Patient out-of-pocket costs ($658 vs $420 [+$238]) and total prescription charges ($6,158 vs $4,366 [+$1,792]) were higher for the longer-term cohort of CDM patients, with similar findings in the SHA dataset. CONCLUSIONS: Adherent, longer-term use of patiromer is associated with significantly lower medical costs offsetting higher prescription costs, driven by the largest changes in inpatient and clinic services at CDM and SHA, respectively. This illustrates an economic value of longer-term adherence to patiromer.

Effect of salinity, Mg2+ and SO42- on "smart water"-induced carbonate wettability alteration in a model oil system.

HYPOTHESIS: We present a systematic study of the "smart water" induced wettability alteration. This process is believed to be greatly affected by the brine salinity and the presence of Mg2+ and SO42- in the brine. EXPERIMENTS AND MODELLING: To characterize the wettability alteration, we perform spontaneous imbibition measurement using Indiana limestone cores and a model oil with added naphthenic acid. Both single-electrolyte-based and seawater-based "smart water" are tested to investigate the effect of Mg2+, SO42- and salinity on wettability alteration. Rock/brine and oil/brine zeta potentials are measured, and the electrostatic component of disjoining pressure is calculated to understand the role of electrostatics in the wettability alteration. The surface concentration of charged species on the limestone surface is analyzed based on a natural carbonate surface complexation model (SCM). FINDINGS: Both the reduction of Na+ and addition of SO42- are found to contribute to wettability alteration. Mg2+ is found to be unfavorable for wettability alteration. Ca2+ is believed to facilitate SO42- with wettability alteration based on the comparison between the single-electrolyte-based and seawater-based brines. The reduction of the Na+ surface complexation (>CaOH⋯Na+0.25) in low salinity brines is believed to be a critical mechanism responsible for wettability alteration based on the SCM calculations.

A semi-experimental procedure for the estimation of permeability of microfluidic pore network.

Microfluidic porous media systems are used for various applications ranging from chemical molecule detection to enhanced oil recovery studies. Absolute permeability data of the microfluidic porous media are important for those applications. However, it is a significant challenge to measure the permeability due to the difficulty in accurately measuring the ultra-low pressure drop across the pore network. This article presents a semi-experimental procedure to estimate the permeability of a microfluidic pore network. The total pressure drop across the porous media chip (ΔPchip) at a given flow rate of a single-phase liquid was obtained from the difference in the inlet pressures at the microfluidic pump with and without the pore network chip connected. The pressure drops in the inlet (ΔPinlet channel) and outlet (ΔPoutlet channel) channels of the pore network are estimated using the hydraulic resistance equation for Poiseuille flow in a wide rectangular cross section. Then the pressure drop across the pore network of the chip (ΔPpore network) is obtained by subtracting (ΔPinlet channel + ΔPoutlet channel) from ΔPchip. Subsequently the permeability of the pore network is calculated using the Darcy's law. •The proposed method is applicable for both homogenous and heterogeneous pore networks.•This method does not require a differential pressure sensor across the microfluidic chip.•This method eliminates the possibility of gas entrapment that can affect the permeability measurement.