Socioeconomic effects of establishing a new stroke center in Central Switzerland

BACKGROUND

Establishment of dedicated Stroke Centers has shown to be effective on the outcome of patients with acute ischemic stroke, as well as mechanical thrombectomy (MTE) in acute large vessel occlusion. The cost-effectiveness of this treatment has also been proven in several countries, but so far not in Switzerland.

METHODS

We compare the pathways and economic impact of patients with acute large vessel occlusions causing acute ischemic stroke before the establishment of the stroke center and MTE in 2016 with the time afterwards in the years 2016-2020. Local data from the Swiss Stroke Registry and hospital accounting as well as economic data from a healthcare insurance company was used for evaluation in an economic model. Both payer and societal perspectives were considered, and probabilistic sensitivity analysis was undertaken to explore uncertainty.

RESULTS

Establishment of a new Stroke Center in Central Switzerland increased the absolute number of thrombectomies from 0 in 2015 to 55 in 2016 to 83 in 2020, as well as the percentage of MTE in large vessel occlusions (LVO) from 50.9% in 2016 to 58.2% in 2020. Over a 15-year horizon, predicted average additional costs of CHF 7,978 were associated with the establishment of a new stroke center, as well as 0.60 quality-adjusted life-years (QALY) per patient and an additional survival of 0.59 years per patient. The calculated incremental cost-effectiveness ratio was therefore CHF 13,297 per QALY gained. When societal costs were included, the new stroke care model was predicted to dominate the old care model. Robustness of model results was confirmed via probabilistic sensitivity analysis.

LIMITATIONS

The results rely on data from a single stroke center and, therefore, cannot be generalized.

CONCLUSIONS

Establishment of a new Stroke Center can be cost-effective and provide better outcomes in terms of functional independence as well as quality-adjusted life-years.

Multi-detector Row CT: Effect of Iodine Dose Reduction on Hepatic and Vascular Enhancement

PURPOSE

To evaluate the impact of different iodine concentrations of intravenous contrast agent on hepatic and vascular enhancement during arterial and porto-venous phase imaging using a 4-channel multi-detector row CT (MDCT).

MATERIAL AND METHODS

One hundred consecutive patients referred for triphasic abdominal MDCT were randomly assigned into four groups receiving different iodine concentration (200, 250, 300 or 350 mg/ml). Non-contrast, arterial, and porto-venous phase 4-channel MDCT imaging was performed (VolumeZoom, Siemens, Germany). A fixed volume of 150 ml intravenous contrast agent at a rate of 3 ml/s was injected using an automatic bolus-tracking system (Care Bolus, Siemens, Erlangen). Hepatic and vascular enhancement values were measured over time and non-contrast values were subtracted in order to compute arterial and porto-venous mean hepatic (MHE) and mean aortic (MAE) enhancement for each group. Mean change of enhancement > 80 HU for the aorta and > 40 HU for the liver during porto-venous phase imaging was considered as sufficient enhancement.

RESULTS

All groups achieved sufficient vascular enhancement during arterial phase imaging; MAE with 350 mg/ml (222 HU) and 300 mg/ml (213HU) was significantly better than with 250 mg (196HU) and 200 mg/ml (169 HU), whereas MHE showed no statistically significant difference between the groups (range 16 - 25 HU). Porto-venous MHE showed increased enhancement with larger concentrations, with significant differences among the groups. Only the higher concentration groups (350 mg/ml und 300 mg/ml) fulfilled in every individual the guidelines for sufficient porto-venous MHE. In the lower concentration groups, 8 patients with 200 mg/ml and 3 patients with 250 mg/ml showed enhancement values below the required minimum.

CONCLUSION

A decrease in iodine contrast agent down to 200 mg/ml concentration is only tenable for propose of vascular aortic and hepatic arterial enhancement, whereas hepatic porto-venous phase imaging still requires concentrations at or above the level of 300 mg/ml.

Solution of an integral equation encountered in rotation therapy

An integral equation relating the lateral absorbed dose profile of a photon beam to the resultant absorbed dose distribution during single-turn rotating-beam therapy has been set up and solved for the case of a cylindrical phantom with the axis of rotation coinciding with the axis of symmetry of the cylinder. In the first approximation the results obtained are also valid when the axis of rotation is somewhat off-centred, even in a phantom that deviates from circular symmetry, provided the rotation is performed in both clockwise and counter clockwise directions. The calculated dose profiles indicate that improved dose uniformity can be achieved using a new type of non-linear wedge-shaped filter, which can easily be designed using the derived general analytic solution to the integral equation.