Neurologist adherence to clinical practice guidelines and costs in patients with newly diagnosed and chronic epilepsy in Germany

PURPOSE

The aim of this study was to evaluate physician adherence to the German Neurological Society guidelines of 2008 regarding initial monotherapy and to determine the cost-of-illness in epilepsy.

METHODS

This was an observational cohort study using health data routinely collected at 55 outpatient neurology practices throughout Germany (NeuroTransData network). Data on socioeconomic status, course of epilepsy, anticonvulsive treatment, and direct and indirect costs were recorded using practice software-based questionnaires.

RESULTS

One thousand five hundred eighty-four patients with epilepsy (785 male (49.6%); mean age: 51.3±18.1years) were enrolled, of whom 507 were newly diagnosed. Initial monotherapy was started according to authorization status in 85.9%, with nonenzyme-inducing drugs in 94.3% of all AEDs. Drugs of first choice by guideline recommendations were used in 66.5%. Total annual direct costs in the first year amounted to €2194 (SD: €4273; range: €55-43,896) per patient, with hospitalization (59% of total direct costs) and anticonvulsants (30%) as the main cost factors. Annual total direct costs decreased by 29% to €1572 in the second year, mainly because of a 59% decrease in hospitalization costs. The use of first choice AEDs did not influence costs. Chronic epilepsy was present in 1077 patients, and total annual direct costs amounted to €1847 per patient, with anticonvulsants (51.0%) and hospitalization (41.0%) as the main cost factors. Potential cost-driving factors in these patients were active epilepsy and focal epilepsy syndrome.

CONCLUSION

This study shows excellent physician adherence to guidelines regarding initial monotherapy in adults with epilepsy. Newly diagnosed patients show higher total direct and hospital costs in the first year upon diagnosis, but these are not influenced by adherence to treatment guidelines.

Effects of tolbutamide and N-benzoyl-D-phenylalanine (NBDP) on the regulation of [Ca2+]i oscillations in mouse pancreatic islets

The sulfonylurea derivative, tolbutamide, and the phenylalanine derivative, N-benzoyl-D-phenylalanine (NBDP), both of which stimulate insulin secretion through interaction with the sulfonylurea receptor (SUR1), were studied for their ability to increase the [Ca(2+)](i) and to interact with the glucose-induced slow large amplitude [Ca(2+)](i) oscillations in isolated mouse pancreatic islets. Tolbutamide as well as NBDP induced [Ca(2+)](i) oscillations of extremely slow frequency. Both compounds also lowered the threshold for the glucose-induced slow large amplitude [Ca(2+)](i) oscillations and significantly reduced their frequency in intact islets as well as in single pancreatic beta cells. These [Ca(2+)](i) oscillations apparently require a glucokinase-mediated glycolytic flux. This conclusion is supported by the observations that KIC, a mitochondrial fuel, cannot replace glucose in this synergism and that mannoheptulose, an inhibitor of glucokinase and glucose-induced insulin secretion, abolishes these slow [Ca(2+)](i) oscillations. In conclusion, these compounds potentiate the effect of glucose. This additive effect is the likely result of a synergistic closing action upon the ATP-sensitive K(+) (K(ATP)) channel, mediated in the case of glucose through an action upon the channel protein itself of ATP generated in glucose catabolism and in the case of tolbutamide and NBDP upon the sulfonylurea receptor (SUR1) associated with this channel.

Differential regulation of [Ca2+]i oscillations in mouse pancreatic islets by glucose, alpha-ketoisocaproic acid, glyceraldehyde and glycolytic intermediates

Glucose induces slow oscillations of the cytoplasmic Ca2+ concentration in pancreatic beta-cells. In order to elucidate the mechanisms responsible for the slow [Ca2+]i oscillations the effects of various nutrient insulin secretagogues on glucose-induced [Ca2+]i oscillations in intact mouse pancreatic islets and single beta-cells were studied. These were the glycolytic intermediates, glyceraldehyde and pyruvate, and the mitochondrial substrate, alpha-ketoisocaproic acid (KIC). Glucose, at a 10 or 15 mM concentration, induced the typical slow oscillations of [Ca2+]i (0.4 min(-1)). At higher glucose concentrations the frequency of these oscillations decreased further (0.2 min(-1)). Glyceraldehyde, an insulin secretagogue like glucose, did not cause slow oscillations of [Ca2+]i in the absence of glucose. However, it exhibited a synergistic action with glucose. Glyceraldehyde, at 3 or 10 mM concentration, induced slow [Ca2+]i oscillations at a substimulatory concentration of 5 mM glucose (0.3-0.4 min(-1)) and reduced the frequency of the glucose-induced [Ca2+]i oscillations at stimulatory concentrations of 10 or 15 mM glucose (0.2 min(-1)). KIC (5 or 10 mM) as well as pyruvate (10 mM), the end product of glycolysis, and its ester methyl pyruvate (10 mM), did not cause slow oscillations of [Ca2+]i in the absence of glucose. In contrast to glyceraldehyde, however, all three compounds were capable of preventing the slow [Ca2+]i oscillations induced by glucose. Mannoheptulose (2 mM), an inhibitor of glucokinase and glucose-induced insulin secretion, reversibly blocked any kind of [Ca2+]i oscillation and returned the [Ca2+]i to a basal level through its ability to inhibit glycolytic flux. It can be concluded therefore that only substrates which generate a glucokinase-mediated metabolic flux through glycolysis and produce glycolytic ATP can induce slow [Ca2+]i oscillations in pancreatic beta-cells.