VNS parameters for clinical response in Epilepsy.

BACKGROUND: While vagus nerve stimulation (VNS) has been in use for over two decades, little professional guidance exists to describe dosing and titration of therapy which is the consequence of a limited amount of evidence developed during the pre-market phase of therapy development. Post-market surveillance of dosing practice has revealed significant deviations from dosing and titration guidance offered by professional societies as well as the manufacturer. OBJECTIVE: This analysis aims to identify a target dose for VNS Therapy in Epilepsy. METHODS: Herein, VNS clinical outcomes are linked to the patient-specific dosing parameters for each study visit (n = 1178 patients). A generalized linear mixed model was built to ascertain the relationship between key stimulation parameters (i.e., Output Current, Pulse Width, Signal Frequency, and Duty Cycle) and clinical response, defined as a 50% or greater reduction in seizure frequency from baseline. Other demographic parameters of interest, such as duration of epilepsy and age at implant, were also explored. RESULTS: A population level target output current and duty cycle for VNS therapy for epilepsy was identified as 1.61 mA and 17.1% duty cycle. Patients with shorter duration of epilepsy were identified to have a higher likelihood to respond to VNS therapy (p < 0.001). While patients who were on the therapy longer were more likely to respond to the therapy, the effect did not interact with the dosing settings - suggesting that patients who have been chronically underdosed may still benefit from achieving the target dose. CONCLUSION: An opportunity exists to improve upon VNS outcomes by aligning clinical practice around this evidence-based target dose.

Quantifying the burden of disease in patients with Lennox Gastaut syndrome.

Lennox-Gastaut syndrome (LGS) is a severe epileptic encephalopathy but there is limited literature characterizing the disease burden despite this being crucial for disease management strategies, and for designing and interpreting clinical trials. We searched the Vagus Nerve Stimulation (VNS) Therapy Patient Outcome Registry including over 7000 patients with drug­resistant epilepsy (DRE). Propensity Score Matching (PSM) matched LGS-DRE patients and non-LGS-DRE patients and frequencies of individual seizure types were assessed. The PSM population included 705 and 1410 DRE patients with and without LGS. 40% of the LGS-DRE group had polypharmacy with 3 antiseizure medications (ASM) while 42% in non-LGS-DRE had polypharmacy with 2 ASMs. Median total monthly seizure frequency was over double in the LGS group: 90 (IQR, 28-312) versus 40 (IQR, 10-150); p < 0.001. This analysis suggests that seizure frequency in LGS patients who later receive VNS is more than double than in non-LGS DRE patients with mostly bilateral tonic-clonic seizures contributing to this difference. Furthermore, ASM burden with poorer seizure control may be greater in LGS patients, however data collection ceased in 2003 and therefore does not take recent ASMs approved for LGS into account. This analysis offers quantitative insight into the burden of disease in patients with LGS.

Short-acting inhaled beta-2-agonists increased the mortality from chronic obstructive pulmonary disease in observational designs.

OBJECTIVE: The effect of short-acting inhaled beta(2)-agonists on mortality from chronic obstructive pulmonary disease (COPD) is controversial. Different observational designs were used to investigate about this topic. STUDY DESIGN AND SETTING: A population-based case-control design was performed, by linking automated health databases from the Varese Province of Italy. Deaths of COPD generated from the cohort of 135,871 patients for whom at least one prescription for drugs used to treat COPD had been dispensed between 1997 and 1999 entered into the study as cases. Up to 20 controls were randomly selected for each case from the cohort after matching on gender, age, and date of cohort entry. Risk ratios were estimated using the case-control, case-crossover, and case-time-control approaches. RESULTS: A total of 222 cases and 3022 controls met the inclusion criteria. Odds ratios (and corresponding 95% confidence intervals) corresponding to more than 0.5 defined-daily-doses were 2.6 (1.7, 4.0), 1.9 (1.1, 3.3), 2.1 (1.1, 4.0), and 2.3 (1.2, 4.6) by using crude and adjusted case-control, case-crossover, and case-time-control estimates, respectively. CONCLUSION: Evidence that higher doses of short-acting inhaled beta(2)-agonists are associated with higher mortality from COPD was consistently supplied by three observational approaches.