Valuation of the Child Health Utility Index 9D (CHU9D)

Objectives The aim of this study was to test the feasibility of estimating preference weights for all health states defined by the Child Health Utility 9D (CHU9D), a new generic measure of health related quality of life for children. This will allow the calculation of quality adjusted life years (QALYs) for use in paediatric economic evaluation. Methods Valuation interviews were undertaken with 300 members of the UK adult general population using standard gamble and ranking valuation methods. Regression modelling was undertaken to estimate models that could predict a value for every health state defined by the CHU9D. A range of models were tested and evaluated based on their predictive performance. Results Models estimated on the standard gamble data performed better than the rank model. All models had a few inconsistencies or insignificant levels and so further modelling was done to estimate a parsimonious consistent regression model, by combining inconsistent levels and removing non significant levels. The final preferred model was an OLS model where all coefficients were significant, there were no inconsistencies and the model had the best predictive performance. Conclusion This research has demonstrated it is feasible to value the CHU9D descriptive system and preference weights for each health state can be generated to allow the calculation of QALYs. The CHU9D can now be used in the economic evaluation of paediatric health care interventions. Further research is needed to investigate the impact of children’s preferences for the health states and what methods could be used to obtain these preferences.economic evaluation; quality of life; paediatric; preference based measures; health state valuation

Assessing the performance of a new generic measure of health related quality of life for children and refining it for use in health state valuation

Purpose: The aims of this research were to pilot and assess the performance of a new generic paediatric health related quality of life measure and to refine the measure to be amenable to health state valuation to make it suitable for use in economic evaluation. Methods: A sample of 247 children was recruited from general and clinical paediatric populations. Each child completed the measure and data was collected to allow assessment of practicality, validity, whether the child could self complete and preferences for alternative wordings that could be used. The measure was refined in light of the results and also to make it amenable to health state valuation. Results: The measure demonstrated good practicality and validity in both the general and clinical paediatric populations with excellent completion rates, a low time to complete and evidence of face, content and construct validity. To make it suitable for health state valuation, the number of dimensions of health related quality of life was reduced from 11 to 9. Conclusions: The measure performed well and the final measure generates health states which should be feasible for valuation. Further research is needed to value the final descriptive system

Developing a descriptive system for a new preference based measure of health related quality of life for children

Aims The use of preference based measures (PBM) of health related quality of life is increasing in health care resource allocation decisions. Whilst there are measures widely used for this purpose in adults, research in the paediatric field is more limited. This paper reports on how the descriptive system for a new paediatric generic PBM of HRQoL was developed, including how the wording and order of the levels for each dimension was determined. The aim was to develop a descriptive system suitable for health state valuation, based on dimensions identified from previous work. Methods The main constraint in designing a descriptive system for a PBM is that the health states defined by the system should be amenable to valuation. Ideally, each dimension needs to contain levels that are ordered within it to fit this criteria well. To develop these levels, the first stage is to determine whether they should be frequency or severity based. To do this, data from the original qualitative work for developing the dimensions was used, reviewing how children described the dimensions. Once this was determined, existing scales from the paediatric literature were reviewed for their suitability and scales were also developed empirically, based on the qualitative interview data from children. The empirical scales were developed by taking the adverbial phrases from the interview work and to confirm the ordinality of these, a ranking exercise was undertaken with children. The resulting scales were applied to the dimensions and a draft descriptive system developed. Results For every dimension, severity arose as the predominant characteristic. No suitable scales were found in the paediatric literature for severity and so empirical scales based on the qualitative data were developed and used which resulted in seven different types of scale. Children were successfully able to rank these scales to determine the ordinality and the scales were applied to all the dimensions in order to form a draft descriptive system. The ordering of the statements resulting from the analysis made sense at face value. Conclusions This work has empirically developed a descriptive system for the dimensions of HRQoL identified in the original interview work. As the methods were based on using data from children, the content validity of the final measure should be increased and the language and terminology is appropriate. Further research is needed to test the descriptive system on a paediatric population and to test the psychometric performance. In addition, due to the constraints of preference based measures, the number of dimensions will need to be reduced to be amenable to valuation. Further research is required to do this

Remote access of the ILLIAC 4

The ILLIAC-4 hardware is described. The Illiac system, the Advanced Research Projects Agency computer network, and IMLAC PDS-1 are included. The space shuttle flow simulation is demonstrated to show the feasibility of using an advanced computer from a remote location

Visual Analogue Scales: do they have a role in the measurement of preferences for health states?

Health state preference data are increasingly used to inform national health care resource allocation decisions. In such circumstances it is important to be confident that the data we provide to decision makers is fit for purpose. Whilst there are many unresolved issues in health state preference measurement, there are some areas of agreement on procedures that are inappropriate. The past ten years have seen the publication of a number of papers reporting substantive problems with the use of visual analogue scales to value health states. In this journal Torrance and colleagues reviewed this literature and concluded that Visual Analogue Scales have a limited but useful role in health state preference measurement. In this paper we critically review the arguments advanced by Torrance and colleagues and argue that it is increasingly clear that Visual Analogue Scales are not an appropriate method and that the time has come to accept that VAS should not be used for health state preference measurement

Starburst-driven galactic winds: I. Energetics and intrinsic X-ray emission

We have performed an extensive hydrodynamical parameter study of starburst-driven galactic winds, motivated by the latest observation data on the best-studied starburst galaxy M82. We study how the wind dynamics, morphology and X-ray emission depend on the host galaxy's ISM distribution, starburst star formation history and strength, and presence and distribution of mass-loading by dense clouds. We find that the soft X-ray emission from galactic winds comes from low filling factor (ff < 2 per cent) gas, which contains only a small fraction (f < 10 per cent) of the mass and energy of the wind, irrespective of whether the wind models are strongly mass-loaded or not. X-ray observations of galactic winds therefore do not directly probe the gas that contains the majority of the energy, mass or metal-enriched gas in the outflow. The soft X-ray emission comes from gas at a wide range different temperatures and densities. Estimates of the physical properties of the hot gas in starburst galaxies, based on fitting the standard simple spectral models to existing X-ray spectra, should therefore be treated with extreme suspicion. The majority of the thermal and kinetic energy of these winds is in a volume filling hot, T approx 10^7 K, component which is extremely difficult to probe observationally due to its low density and hence low emissivity. Most of the total energy is in the kinetic energy of this hot gas, a factor which must be taken into account when attempting to constrain wind energetics observationally. We also find that galactic winds are efficient at transporting large amounts of energy out of the host galaxy, in contrast to their inefficiency at transporting mass out of star-forming galaxies. (Abridged)Comment: Accepted for publication in MNRAS. Letter page size postscript available from http://adcam.pha.jhu.edu/~dks/dks_published.htm

Ion-retarding lens improves the abundance sensitivity of tandem mass spectrometers

Ion-retarding lens which increases the abundance sensitivity of tandem magnetic-analyzer mass spectrometers measures isotopes of low abundance in mass positions adjacent to isotopes of high abundance. The lens increases the abundance sensitivity for isotopes lying farther from high abundance isotopes than the energy cutoff of the lens

Predicting X-ray emission from wind-blown bubbles - Limitations of fits to ROSAT spectra

Wind-blown bubbles, from those around massive O and Wolf-Rayet stars, to superbubbles around OB associations and galactic winds in starburst galaxies, have a dominant role in determining the structure of the Interstellar Medium. X-ray observations of these bubbles are particularly important as most of their volume is taken up with hot gas, 1E5 < T (K) < 1E8. However, it is difficult to compare X-ray observations, usually analysed in terms of single or two temperature spectral model fits, with theoretical models, as real bubbles do not have such simple temperature distributions. In this introduction to a series of papers detailing the observable X-ray properties of wind-blown bubbles, we describe our method with which we aim to solve this problem, analysing a simulation of a wind-blown bubble around a massive star. We model a wind of constant mass and energy injection rate, blowing into a uniform ISM, from which we calculate X-ray spectra as would be seen by the ROSAT PSPC. We compare the properties of the bubble as would be inferred from the ROSAT data with the true properties of the bubble in the simulation. We find standard spectral models yield inferred properties that deviate significantly from the true properties, even though the spectral fits are statistically acceptable, and give no indication that they do not represent to true spectral distribution. Our results suggest that in any case where the true source spectrum does not come from a simple single or two temperature distribution the "observed" X-ray properties cannot naively be used to infer the true properties.Comment: 14 pages, LaTeX with 13 eps figures, condensed abstract. MNRAS in pres

The Energetics and Mass-loss of Mrk33

We present ROSAT HRI X-ray data and optical imaging of the important dwarf starburst Markarian 33. We find an extended, complex, shell-like morphology in the X-ray emission, with an extent of 2.3 x 1.9kpc, coincident with the bright star-forming regions at the centre of the galaxy. The physical extent of this X-ray emission from Mrk 33 is very similar to the observed Halpha emission, and suggests that the bulk of the X-ray emission is coming from an expanding superbubble. We estimate the age and mass of Mrk 33's starburst to be 5.8 Myr and 6.9 x 10^{6} Msolar respectively with the energy injection rate in the central regions of the galaxy being 10^{41} erg/s, while the associated mass-loss rate from the star-forming regions is estimated to be 0.2 Msolar/yr. We suggest that the X-ray emission is predominantly powered by starburst type activity and argue that a blowout in the form of a galactic wind is the most likely fate for Mrk 33 resulting in the loss of most of the galaxy's metal-enriched material and a small fraction (<1 per cent) of the ISM.Comment: 13 pages, 6 figures, accepted for publication in MNRA

Can consumer research panels form an effective part of the cancer research community?

The North Trent Cancer Research Network’s Consumer Research Panel (NTCRN CRP) was established in December 2001 by the Academic Unit of Supportive Care at the University of Sheffield. In three years, the CRP has succeeded in nurturing a climate of sustainable consumer involvement within the NTCRN and this has become embedded in the culture of the network. Furthermore, the panel have championed a sustainable development of consumer involvement in health and social care research by testing new ground and forging a new way of working between health professionals and patients and carers. The CRP model has been held up as an example to other cancer networks, with new panels being set up around the country to emulate its success. This paper describes the Sheffield model of patient and public involvement and using the eight key principles of successful consumer involvement in research, identified in a recent paper by Telford et al (2003), provides a useful framework for analysing the work of the Panel. This demonstrates how consumers and professionals can inform each other to work constructively and synergistically to achieve impressive research results. The need for measurable outcomes to assess the impact and effect of consumer involvement is finally explored