Characterization and quantification of adeno-associated virus capsid-loading states by multi-wavelength analytical ultracentrifugation with UltraScan.

Aim: We present multi-wavelength (MW) analytical ultracentrifugation (AUC) methods offering superior accuracy for adeno-associated virus characterization and quantification. Methods: Experimental design guidelines are presented for MW sedimentation velocity and analytical buoyant density equilibrium AUC. Results: Our results were compared with dual-wavelength AUC, transmission electron microscopy and mass photometry. In contrast to dual-wavelength AUC, MW-AUC correctly quantifies adeno-associated virus capsid ratios and identifies contaminants. In contrast to transmission electron microscopy, partially filled capsids can also be detected and quantified. In contrast to mass photometry, first-principle results are obtained. Conclusion: Our study demonstrates the improved information provided by MW-AUC, highlighting the utility of several recently integrated UltraScan programs, and reinforces AUC as the gold-standard analysis for viral vectors.

Expected Budget Impact and Health Outcomes of Expanded Use of Vagus Nerve Stimulation Therapy for Drug-Resistant Epilepsy.

INTRODUCTION: The objective was to estimate, from the perspective of a managed care organization in the United States, the budget impact and effect on health outcomes of expanded use of vagus nerve stimulation [VNS (VNS Therapy®)] among patients aged ≥ 12 years with drug-resistant epilepsy (DRE) with partial-onset seizures. METHODS: An Excel model was developed to compare the costs of continued anti-epileptic drug (AED) treatment with the costs of VNS plus AED treatment. The number of people eligible for VNS was estimated using published prevalence data and an estimate of the percentage of eligible patients currently without VNS. Costs included VNS device, placement, programming, and battery changes; adverse events associated with VNS (cough, voice alteration, device removal resulting from surgical site infection); AEDs; and seizure-related costs affected by seizure frequency, which affects resource utilization (i.e., hospitalizations, emergency department visits, neurologist visits). To estimate the potential savings with VNS due to a reduction in seizure frequency, the budget impact model uses the results of an underlying Markov model to estimate seizure-related costs by seizure frequency. Transitions occurred among four health states, defined by number of seizures per month (i.e., seizure-free, ≤ 1, > 1 to < 10, ≥ 10) on a 3-month cycle based on published clinical trials and registry data. RESULTS: VNS resulted in an estimated net cost savings, on average, over 5 years, due to the expected reduction in seizure frequency. The initial cost of the VNS device, placement, and programming was estimated to be offset 1.7 years after VNS device placement. Reductions in hospitalizations were the main contributor to the cost savings with VNS. CONCLUSIONS: VNS is a proven intervention that offers a long-term solution for patients with DRE by reducing seizure frequency, which leads to lower resource utilization and lower costs. FUNDING: LivaNova PLC.

Correction to: Expected Budget Impact and Health Outcomes of Expanded Use of Vagus Nerve Stimulation Therapy for Drug-Resistant Epilepsy.

The article "Expected Budget Impact and Health Outcomes of Expanded Use of Vagus Nerve Stimulation Therapy for Drug-Resistant Epilepsy", written by Molly F. Purser, Deirdre M. Mladsi, Alan Beckman, Francesca Barion, John Forsey was originally published electronically on the publisher's internet portal (currently SpringerLink) on August 24, 2018 without open access.

A study of the impact of VNS on health care utilisation in England.

PURPOSE: To compare hospital service use before and after VNS therapy implantation in a sample of drug-resistant people with epilepsy. METHOD: The before and after study was performed using anonymised Hospital Episode Statistics (HES) data from one year before to 3 years after implantation in 321 patients from data collected between April 2009 to July 2011. Episodes relating to out-patient clinic, Accident and Emergency (A&E) department attendance, hospital admissions and length of stay were collected and compared. Descriptive statistics are used to summarise patient demographics, patient pathways and resource usage before and after VNS implantation. Means and proportions were reported on continuous variables, proportion and frequency on categorical variables. Trends of activity over time were determined using before and after VNS comparisons and tested with the Wilcoxon Signed-rank (WSR) test. RESULTS: The summary statistics indicate a drop in resource use in terms of in-patient bed-days (21% decrease), elective in-patient episodes (7% decrease) and non-elective in-patient episodes (14% decrease). There was an increase in the quarterly average out-patient appointments by 12%. The A&E attendance outcome recorded a mean increase in quarterly attendances of 9% but a slight decrease when subject to a signed rank test. These contradictory results should therefore be treated with caution. CONCLUSION: VNS Therapy may be associated with an overall reduction in health service resource use.