An observational pilot study: Prevalence and cost of high frequency emergency department users at Örebro University Hospital, Sweden.

BACKGROUND: There is little research on high frequency emergency department users (HEDU) in Sweden. We aim to determine the prevalence and costs of HEDU compared to non-HEDU at Örebro University Hospital (ÖUH). Additionally, we will determine the factors and outcomes associated with being a HEDU. METHODS: This was a retrospective, observational cohort study of ED patients presenting to ÖUH, Sweden between 2018-19. Analyses used electronic registry, ambulance, and cost data. The definition for HEDU was ≥4 visits/year. HEDUs were categorized further into Repeat, High and Super HEDU with 4-7, 8-18 and ≥19 visits/year, respectively. We used multivariable logistic regression to determine the adjusted odds ratios for factors and outcomes between HEDU and non-HEDU. FINDINGS: Of all ÖUH ED patients, 6.1% were HEDU and accounted for 22.4% of ED visits and associated costs. Compared to the mean cost of non-HEDU, the Repeat, High and Super HEDU were more costly by factors of 4, 8 and 27, respectively. The HEDUs were more likely to be male, self-referred, present with abdominal pain, arrive by ambulance, at night and from the Örebro municipal region. Super HEDU were more likely to be of adult age and assigned lower acuity scores. HEDU were more likely to be directed to the surgical zone, less likely to receive radiologic imaging or achieve a 4-hr time target. In contrast to the Repeat and High HEDU, Super HEDU were less likely to be admitted, but more likely to leave without being seen. CONCLUSION: ÖUH has a HEDU population with associated factors and outcomes. They account for a substantial proportion of ED costs compared to non-HEDU.

The dosimetric impact of including the patient table in CT dose estimates.

The purpose of this study was to evaluate the dosimetric impact of including the patient table in Monte Carlo CT dose estimates for both spiral scans and scan projection radiographs (SPR). CT scan acquisitions were simulated for a Siemens SOMATOM Force scanner (Siemens Healthineers, Forchheim, Germany) with and without a patient table present. An adult male, an adult female and a pediatric female voxelized phantom were simulated. The simulated scans included tube voltages of 80 and 120 kVp. Spiral scans simulated without a patient table resulted in effective doses that were overestimated by approximately 5% compared to the same simulations performed with the patient table present. Doses in selected individual organs (breast, colon, lung, red bone marrow and stomach) were overestimated by up to 8%. Effective doses from SPR acquired with the x-ray tube stationary at 6 o'clock (posterior-anterior) were overestimated by 14-23% when the patient table was not included, with individual organ dose discrepancies (breast, colon, lung red bone marrow and stomach) all exceeding 13%. The reference entrance skin dose to the back were in this situation overestimated by 6-15%. These results highlight the importance of including the patient table in patient dose estimates for such scan situations.

Source modeling for Monte Carlo dose calculation of CT examinations with a radiotherapy treatment planning system.

PURPOSE: Radiation dose to patients undergoing examinations with Multislice Computed Tomography (MSCT) as well as Cone Beam Computed Tomography (CBCT) is a matter of concern. Risk management could benefit from efficient replace rational dose calculation tools. The paper aims to verify MSCT dose calculations using a Treatment Planning System (TPS) for radiotherapy and to evaluate four different variations of bow-tie filter characterizations for the beam model used in the dose calculations. METHODS: A TPS (RayStation™, RaySearch Laboratories, Stockholm, Sweden) was configured to calculate dose from a MSCT (GE Healthcare, Wauwatosa, WI, USA). The x-ray beam was characterized in a stationary position the by measurements of the Half-Value Layer (HVL) in aluminum and kerma along the principal axes of the isocenter plane perpendicular to the beam. A Monte Carlo source model for the dose calculation was applied with four different variations on the beam-shaping bow-tie filter, taking into account the different degrees of HVL information but reconstructing the measured kerma distribution after the bow-tie filter by adjusting the photon sampling function. The resulting dose calculations were verified by comparison with measurements in solid water as well as in an anthropomorphic phantom. RESULTS: The calculated depth dose in solid water as well as the relative dose profiles was in agreement with the corresponding measured values. Doses calculated in the anthropomorphic phantom in the range 26-55 mGy agreed with the corresponding thermo luminescence dosimeter (TLD) measurements. Deviations between measurements and calculations were of the order of the measurement uncertainties. There was no significant difference between the different variations on the bow-tie filter modeling. CONCLUSIONS: Under the assumption that the calculated kerma after the bow-tie filter replicates the measured kerma, the central specification of the HVL of the x-ray beam together with the kerma distribution can be used to characterize the beam. Thus, within the limits of the study, a flat bow-tie filter with an HVL specified by the vendor suffices to calculate the dose distribution. The TPS could be successfully configured to replicate the beam movement and intensity modulation of a spiral scan with dose modulation, on the basis of the specifications available in the metadata of the digital images and the log file of the CT.

Natriuretic peptides and integrated risk assessment for cardiovascular disease: an individual-participant-data meta-analysis.

BACKGROUND: Guidelines for primary prevention of cardiovascular diseases focus on prediction of coronary heart disease and stroke. We assessed whether or not measurement of N-terminal-pro-B-type natriuretic peptide (NT-proBNP) concentration could enable a more integrated approach than at present by predicting heart failure and enhancing coronary heart disease and stroke risk assessment. METHODS: In this individual-participant-data meta-analysis, we generated and harmonised individual-participant data from relevant prospective studies via both de-novo NT-proBNP concentration measurement of stored samples and collection of data from studies identified through a systematic search of the literature (PubMed, Scientific Citation Index Expanded, and Embase) for articles published up to Sept 4, 2014, using search terms related to natriuretic peptide family members and the primary outcomes, with no language restrictions. We calculated risk ratios and measures of risk discrimination and reclassification across predicted 10 year risk categories (ie, <5%, 5% to <7·5%, and ≥7·5%), adding assessment of NT-proBNP concentration to that of conventional risk factors (ie, age, sex, smoking status, systolic blood pressure, history of diabetes, and total and HDL cholesterol concentrations). Primary outcomes were the combination of coronary heart disease and stroke, and the combination of coronary heart disease, stroke, and heart failure. FINDINGS: We recorded 5500 coronary heart disease, 4002 stroke, and 2212 heart failure outcomes among 95 617 participants without a history of cardiovascular disease in 40 prospective studies. Risk ratios (for a comparison of the top third vs bottom third of NT-proBNP concentrations, adjusted for conventional risk factors) were 1·76 (95% CI 1·56-1·98) for the combination of coronary heart disease and stroke and 2·00 (1·77-2·26) for the combination of coronary heart disease, stroke, and heart failure. Addition of information about NT-proBNP concentration to a model containing conventional risk factors was associated with a C-index increase of 0·012 (0·010-0·014) and a net reclassification improvement of 0·027 (0·019-0·036) for the combination of coronary heart disease and stroke and a C-index increase of 0·019 (0·016-0·022) and a net reclassification improvement of 0·028 (0·019-0·038) for the combination of coronary heart disease, stroke, and heart failure. INTERPRETATION: In people without baseline cardiovascular disease, NT-proBNP concentration assessment strongly predicted first-onset heart failure and augmented coronary heart disease and stroke prediction, suggesting that NT-proBNP concentration assessment could be used to integrate heart failure into cardiovascular disease primary prevention. FUNDING: British Heart Foundation, Austrian Science Fund, UK Medical Research Council, National Institute for Health Research, European Research Council, and European Commission Framework Programme 7.

Equalization and Participation for All: Swedish Disability Policy at a Crossroads.

The political line in Swedish disability policy advocates the use of generalized solutions in order to fit potential needs of the largest possible group of people and, where needed, special solutions to bridge the remaining gap between the generalized level of accessibility and additional individual needs. This is referred to as the disability perspective (DP). The DP has embraced two tracks: one that pertains to generalized solutions that promote an overall high level of accessibility and usability, and another one that pertains to different types of individual support for people with disabilities. The present study is a self-reflective inquiry on key issues for the development of future disability policies. Five experts entered a discussion about the pros and cons concerning the DP. This confirmed or refuted assumptions, dilemmas, themes as well as reoccurring patterns in the political viva voce procedure that has formed the contemporary disability policy. Over the course of time, the experts believed that the DP had nurtured a belief that there is a dichotomy. This may have created an imbalance in the relation between the DP and policies such as those concerning healthcare and social care. With a clearer focus on interdependence, the experts saw synergies between needs for assistive technology, assistive products and the requirements for the built environment.

Diabetes mellitus, high BMI and low education level predict sudden cardiac death within 24 hours of incident myocardial infarction.

BACKGROUND: More than half of cardiovascular mortality occurs outside the hospital, mainly due to consistently low survival rates from out-of-hospital cardiac arrest. METHODS: This is a prospective, nested, case-control study derived from the Västerbotten Intervention Programme and the World Health Organization's Multinational Monitoring of Trends and Determinants in Cardiovascular Disease study in northern Sweden (1986-2006). To determine predictors for sudden cardiac death risk factors for cardiovascular disease were compared between incident myocardial infarction with sudden cardiac death (n = 363) and survivors of incident myocardial infarction (n = 1998) using multivariate logistic regression analysis. RESULTS: Diabetes had the strongest association with sudden cardiac death out of all evaluated risk factors (odds ratio (OR) 1.83, 95% confidence interval (CI) 1.30-2.59), followed by low education (OR 1.55, 95% CI 1.19-2.01), high body mass index (OR 1.05, 95% CI 1.02-1.08) and male sex (OR 1.42, 95% CI 1.001-2.01). CONCLUSIONS: The pattern of risk factors for incident myocardial infarction is different among survivors and those who die within 24 hours. The risk factors that contribute the most to death within 24 hours are diabetes mellitus, high body mass index and low education level, and can be addressed at both the public health level and by general practitioners.

Liquid ionization chamber initial recombination dependence on LET for electrons and photons.

The possibility of indirect measurements of linear energy transfer (LET) with a liquid ionization chamber (LIC) has been investigated by studying initial recombination losses at different applied voltages. A linear fit is made to the voltage-signal curve and the intersection point of the fit and the voltage-axis is shown to correlate with LET. The LIC applied voltages were 100-700 V, which corresponds to electric field strengths between 0.3 and 2.0 MV m(-1). Several different photon and electron beams have been studied, and by using MCNPX™ the respective LET spectra have been determined. The beam qualities in this study were found to have a fluence averaged LET between 0.17 and 1.67 keV µm(-1) and a corresponding dose averaged LET between 0.97 and 4.62 keV µm(-1). For the experimental data in this study the linear fit method yields consistent results with respect to Monte Carlo simulated LET values. A calibration curve for LET determination is provided for the LIC used in the present work.

On the property of measurements with the PTW microLion chamber in continuous beams.

PURPOSE: The performance of liquid ionization chambers, which may prove to be useful tools in the field of radiation dosimetry, is based on several chamber and liquid specific characteristics. The present work investigates the performance of the PTW microLion liquid ionization chamber with respect to recombination losses and perturbations from ambient electric fields at various dose rates in continuous beams. METHODS: In the investigation, experiments were performed using two microLion chambers, containing isooctane (C(8)H(18)) and tetramethylsilane [Si(CH(3))(4)] as the sensitive media, and a NACP-02 monitor chamber. An initial activity of approximately 250 GBq (18)F was employed as the radiation source in the experiments. The initial dose rate in each measurement series was estimated to 1.0 Gy min(-1) by Monte Carlo simulations and the measurements were carried out during the decay of the radioactive source. In the investigation of general recombination losses, employing the two-dose-rate method for continuous beams, the liquid ionization chambers were operated at polarizing voltages 25, 50, 100, 150, 200, and 300 V. Furthermore, measurements were also performed at 500 V polarizing voltage in the investigation of the sensitivity of the microLion chamber to ambient electric fields. RESULTS: The measurement results from the liquid ionization chambers, corrected for general recombination losses according to the two-dose-rate method for continuous beams, had a good agreement with the signal to dose linearity from the NACP-02 monitor chamber for general collection efficiencies above 70%. The results also displayed an agreement with the theoretical collection efficiencies according to the Greening theory, except for the liquid ionization chamber containing isooctane operated at 25 V. At lower dose rates, perturbations from ambient electric fields were found in the microLion chamber measurement results. Due to the perturbations, measurement results below an estimated dose rate of 0.2 Gy min(-1) were excluded from the present investigation of the general collection efficiency. The perturbations were found to be more pronounced when the chamber polarizing voltage was increased. CONCLUSIONS: By using the two-dose-rate method for continuous beams, comparable corrected ionization currents from experiments in low and medium energy photon beams can be achieved. However, the valid range of general collection efficiencies has been found to vary in a comparison between experiments performed in continuous beams of 120 kVp x ray, and the present investigation of 511 keV annihilation photons. At very high dose rates in continuous beams, there are presently no methods that can be used to correct for general recombination losses and at low dose rates the microLion chamber may be perturbed by ambient electric fields. Increasing the chamber polarizing voltage, which diminishes the general recombination effect, was found to increase the microLion chamber sensitivity to ambient electric fields. Prudence is thus advised when employing the microLion chamber in radiation dosimetry, as ambient electric fields of the strength observed in the present work may be found in many common situations. Due to uncertainties in the theoretical basis for recombination losses in liquids, further studies on the underlying theories for the initial and general recombination effect are needed if liquid ionization chambers are to become a viable option in high precision radiation dosimetry.