4,067 research outputs found
Roderick Sykes' mural, Alta Loma Elementary School, Los Angeles, 1972-1992
No full textRoderick Sykes' mural, Alta Loma Elementary School, untitled, Los Angeles, 1972-1992. Alta Loma School, exterior, 1745 Vineyard Avenue (between Saturn Street and St. Elmo Drive). There are four murals on campus, done over a period of several years. The most recent, designed by Oscar de Leon, in 1990, is of a bookworm, eating his way through the middles of eight books. It is located at the rear of the Administration building, just outside the library. Outside the Classroom building is a colorful portrait of five children designed by Roderick Sykes. Nearby, on the steps to the building's second floor are more faces. On the Saturn Avenue side of the school, in the outside lunch area, is a three-panel mural about food. First is a farm scene, then a grocery store, and third and early Thanksgiving with pilgrims and Native Americans. By children under the supervision of Roderick Sykes. Sponsored by School Beautification Project. -- Dunitz, Street gallery, p. 77, #66
A multilevel analysis of the effects of rurality and social deprivation on premature limiting long term illness
No full textSTUDY OBJECTIVE---To examine the geographical variation in self perceived morbidity in the south west of England, and assess the associations with rurality and social deprivation.DESIGN---A geographically based cross sectional study using 1991 census data on premature Limiting Long Term Illness (LLTI). The urban-rural and intra-rural variation in standardised premature LLTI ratios is described, and correlation and regression analyses explore how well this is explained by generic deprivation indices. Multilevel Poisson modelling investigates whether Customised Deprivation Profiles (CDPs) and area characteristics improve upon the generic indices.SETTING---Nine counties in the south west of EnglandPARTICIPANTS---The population of the south west enumerated in the 1991 census.MAIN RESULTS---Intra-rural variation is apparent, with higher rates of premature LLTI in remoter areas. Together with high rates in urban areas and lower rates in the semi-rural areas this indicates the existence of a U shaped relation with rurality. The generic deprivation indices have strong positive relations with premature LLTI in urban areas, but these are a lot weaker in semi-rural and rural locations. CDPs improve upon the generic indices, especially in the rural settings. A substantial reduction in unexplained variation in rural areas is seen after controlling for the level of local isolation, with higher isolation, at the wider geographical scale, being related to higher levels of LLTI.CONCLUSIONS---This study highlights the need to treat rural areas as heterogeneous, although this has not been the tendency in health research. Generic deprivation indices are unlikely to be a true reflection of levels of deprivation in rural environments. The importance of CDPs that are specific to the area type and health outcome is emphasised. The significance of physical isolation suggests that accessibility to public and health services may be an important issue, and requires further research
Roderick G. W. — Man and Heredity
No full textJ. A. Roderick G. W. — Man and Heredity. In: Population, 26ᵉ année, n°6, 1971. p. 1176
A methodological review of how heterogeneity has been examined in systematic reviews of diagnostic test accuracy
No full textBackground
Systematic reviews of therapeutic interventions are now commonplace in many if not most areas of healthcare, and in recent years interest has turned to applying similar techniques to research evaluating diagnostic tests. One of the key parts of any review is to consider how similar or different the available primary studies are and what impact any differences have on studies’ results. Between-study differences or heterogeneity in results can result from chance, from errors in calculating accuracy indices or from true heterogeneity, that is, differences in design, conduct, participants, tests and reference tests. An important additional consideration for diagnostic studies is differences in results due to variations in the chosen threshold for a positive result for either the index or reference test.Dealing with heterogeneity is particularly challenging for diagnostic test reviews, not least because test accuracy is conventionally represented by a pair of statistics and not by a single measure of effect such as relative risk, and as a result a variety of statistical methods are available that differ in the way in which they tackle the bivariate nature of test accuracy data:
methods that undertake independent analyses of each aspect of test performance methods that further summarise test performance into a single summary statistic methods that use statistical models that simultaneously consider both dimensions of test performance. The validity of a choice of meta-analytical method depends in part on the pattern of variability (heterogeneity) observed in the study results. However, currently there is no empirical guidance to judge which methods are appropriate in which circumstances, and the degree to which different methods yield comparable results. All this adds to the complexity and difficulty of undertaking systematic reviews of diagnostic test accuracy.Objectives
Our objective was to review how heterogeneity has been examined in systematic reviews of diagnostic test accuracy studies. Methods
Systematic reviews that evaluated a diagnostic or screening test by including studies that compared a test with a reference test were identified from the Centre for Reviews and Dissemination’s Database of Abstracts of Reviews of Effects. Reviews for which structured abstracts had been written up to December 2002 were screened for inclusion. Data extraction was undertaken using standardised data extraction forms by one reviewer and checked by a second.Results
A total of 189 systematic reviews met our inclusion criteria and were included in the review. The median number of studies included in the reviews was 18 [inter-quartile range (IQR) 20]. Meta-analyses (n = 133) have a higher number with a median of 22 studies (IQR 20) compared with 11 (IQR 13) for narrative reviews (n = 56).Identification of heterogeneity
Graphical plots to demonstrate the spread in study results were provided in 56% of meta-analyses; in 79% of cases these were in the form of plots of sensitivity and specificity in the receiver operating characteristic (ROC) space (commonly termed ‘ROC plots’).Statistical tests to identify heterogeneity were used in 32% of reviews: 41% of meta-analyses and 9% of reviews using narrative syntheses. The c2 test and Fisher’s exact test to assess heterogeneity in individual aspects of test performance were most commonly used. In contrast, only 16% of meta-analyses used correlation coefficients to test for a threshold effect.Type of syntheses used
A narrative synthesis was used in 30% of reviews. Of the meta-analyses, 52% carried out statistical pooling alone, 18% conducted only summary receiver operator characteristic (SROC) analyses and 30% used both methods of statistical synthesis. Of the reviews that pooled accuracy indices, most pooled each aspect of test performance separately with only a handful producing single summaries of test performance such as the diagnostic odds ratio. For those undertaking SROC analyses, the main differences between the models used were the weights chosen for the regression models. In fact, in 42% of cases (27/64) the use of, or choice of, weight was not provided by the review authors. The proportion of reviews using statistical pooling alone has declined over time from 67% in 1995 to 42% in 2001, with a corresponding increase in the use of SROC methods, from 33% to 58%. However, two-thirds of those using SROC methods also carried out statistical pooling rather than presenting only SROC models. Reviews using SROC analyses also tended to present their results as some combination of sensitivity and specificity rather than using alternative, perhaps less clinically meaningful, means of data presentation such as diagnostic odds ratios.Investigation of heterogeneity sources
Three-quarters of meta-analyses attempted to investigate statistically possible sources of variation, using subgroup analysis (76) or regression analysis (44). The median number of variables investigated was four, ranging from one variable in 20% of reviews to over six in 27% of reviews. The ratio of median number of variables to median number of studies was 1:6.The impact of clinical or socio-demographic variables was investigated in 74% of these reviews and test- or threshold-related variables in 79%. At least one quality-related variable was investigated in 63% of reviews. Within this subset, the most commonly considered variables were the use of blinding (41% of reviews), sample size (33%), the reference test used (28%) and the avoidance of verification bias (25%).Conclusions
The emphasis on pooling individual aspects of diagnostic test performance and the under-use of statistical tests and graphical approaches to identify heterogeneity perhaps reflect the uncertainty in the most appropriate methods to use and also greater familiarity with more traditional indices of test accuracy. This is an indication of the level of difficulty and complexity of carrying out these reviews. It is strongly suggested that in such reviews meta-analyses are carried out with the involvement of a statistician familiar with the field
Potential use of routine databases in health technology assessment
No full textIntroductionThis report defines health technology assessment to include the investigation of (i) effectiveness, (ii) diffusion and equity and (iii) cost – all as applied to the range of health technologies (HTs) including pharmaceuticals, devices, procedures and settings. Key characteristics of routine data are regular collection, standard definitions, obligatory completion and representative coverage.
AimsThe aims of this study were to: 1. develop criteria for classifying databases in relation to their potential use in HT assessment
2. list the databases of relevance in the UK
3. apply the criteria for classifying databases to that list
4. explore the extent to which prioritised databases could pick up those HTs being assessed by the National Coordinating Centre for Health Technology Assessment (NCCHTA)
5. investigate the extent to which these databases have been used in HT assessment
6. explore the degree to which databases, so used, have been validated
7. estimate the cost of the prioritised databases
8. make suggestions for facilitating the use of routine data for HT assessment.
MethodsA ‘first principles’ examination of the data necessary for each type of HT assessment was central to aim 1, supplemented by literature searches and a historical review.A long list (aim 2) was developed using selected literature and by networking with people with relevant experience.The principal investigators applied the criteria to the long list (aim 3) using annotations of each. Comments of the ‘keepers’ of the prioritised databases were incorporated.For aim 4, details of 161 topics funded by the NHS R&D Health Technology Assessment (HTA) programme were reviewed iteratively by the principal investigators.Uses of databases in HT assessments (aim 5) were identified by literature searches, which included the title of each prioritised database as a keyword. Annual reports of databases were examined and ‘keepers’ queried. Each identified use was checked by the three principal investigators.The validity of each database (aim 6) was assessed using criteria based on a literature search and involvement by the authors in a national academic network. The ‘keepers’ of databases were queried.The costs of databases (aim 7) were established from annual reports, enquiries to ‘keepers’ of databases and ‘guesstimates‘ based on cost per record.The proposals under aim 8 were based on the above and discussion between authors.
ResultsTo be of value in HT assessment, databases must at least identify a well-defined HT. Additional dimensions depend on the type of HT assessment. For assessing effectiveness, equity and diffusion, routine databases were classified into three broad groups: * group I databases, identifying both HTs and health states
* group II databases, identifying the HTs, but not a health state
* group III databases, identifying health states, but not an HT.Group I datasets were disaggregated into clinical registries, clinical administrative databases and population-oriented databases. Group III were disaggregated into adverse event reporting, confidential enquiries, disease-only registers and health surveys.Databases in group I can be used not only to assess effectiveness but also to assess diffusion and equity. Databases in group II can only assess diffusion. Group III has restricted scope for assessing HTs, except for analysis of adverse events.For use in costing, databases need to include unit costs or prices. Some databases included unit cost as well as a specific HT.A long list of around 270 databases was identified at the level of the UK, England and Wales or England (over 1000 including Scotland, Wales and Northern Ireland).Allocation of these to the above groups identified around 60 databases with some potential for HT assessment, roughly half to group I. Eighteen clinical registers were identified as having the greatest potential although the clinical administrative datasets had potential mainly owing to their inclusion of a wide range of technologies. Only two databases were identified that could be directly used in costing.The review of the potential capture of HTs prioritised by the UK’s NHS R&D HTA programme showed that only 10% would be captured in these databases, mainly drugs prescribed in primary care.The review of the use of routine databases in any form of HT assessment indicated that clinical registers were mainly used for national comparative audit. Some databases have only been used in annual reports, usually time trend analysis. A few peer-reviewed papers used a clinical register to assess the effectiveness of a technology, particularly those with relatively simple outcomes (conceptions from in vitro fertilisation or graft failure in organ transplants). The authorship of such studies suggests that accessibility is a barrier to using most databases.Clinical administrative databases (group Ib) have been mainly used to build population needs indices and performance indicators.A review of the validity of used databases showed that although internal consistency checks were common, relatively few had any form of external audit. Some comparative audit databases have data scrutinised by participating units. Issues around coverage and coding have, in general, received little attention.NHS funding of databases has been mainly for ‘Central Returns’ for management purposes, which excludes those databases with the greatest potential for HT assessment. Funding for these was various, but some are unfunded, relying on goodwill. The estimated total cost of databases in group I plus selected databases from groups II and III has been estimated at £50 million or around 0.1% of annual NHS spend. A few databases with limited potential for health technology assessment account for the bulk of spending.
Conclusions and recommendations for further researchProposals for policy include clarification of responsibility for the strategic development of databases, improved resourcing, and issues around coding, confidentiality, ownership and access, maintenance of clinical support, optimal use of information technology, filling gaps and remedying deficiencies.Recommendations for researchers include closer policy links between routine data and R&D, and selective investment in the more promising databases. Recommended research topics include optimal capture and coding of the range of HTs, international comparisons of the role, funding and use of routine data in healthcare systems and use of routine databases in trials and in modelling. Independent evaluations are recommended for information strategies (such as those around the NSFs and various collaborations) and for electronic patient and health records
The inter-relationships between three proxies of health care need at the small area level: an urban/rural comparison
No full textStudy objective: To examine the relations between geographical variations in mortality, morbidity, and deprivation at the small area level in the south west of England and to assess whether these relations vary between urban and rural areas. Design: A geographically based cross sectional study using 1991 census data on premature limiting long term illness (LLTI) and socioeconomic characteristics, and 1991–1996 data on all cause premature mortality. The interrelations between the three widely used proxies of health care need are examined using correlation coefficients and scatterplots. The distribution of standardised LLTI residuals from a regression analysis on mortality are mapped and compared with the distribution of urban and rural areas. Multilevel Poisson modelling investigates whether customised deprivation profiles improve upon a generic deprivation index in explaining the spatial variation in morbidity and mortality after controlling for age and sex. These relations are examined separately for urban, fringe, and rural areas. Setting: Nine counties in the south west of England. Participants: Those aged between 0–64 who reported having a LLTI in the 1991 census, and those who died during 1991–1996 aged 0–74. Main results: Relations between both health outcomes and generic deprivation indices are stronger in urban than rural areas. The replacement of generic with customised indices is an improvement in all area types, especially for LLTI in rural areas. The relation between mortality and morbidity is stronger in urban than rural areas, with levels of LLTI appearing to be greater in rural areas than would be predicted from mortality rates. Despite the weak direct relations between mortality and morbidity, there are strong relations between the customised deprivation indices computed to predict these outcomes in all area types. Conclusions: The improvement of the customised deprivation indices over the generic indices, and the similarity between the mortality and morbidity customised indices within area types highlights the importance of modelling urban and rural areas separately. Stronger relations between mortality and morbidity have been revealed at the local authority level in previous research providing empirical evidence that the inadequacy of mortality as a proxy for morbidity becomes more marked at lower levels of aggregation, especially in rural areas. Higher levels of LLTI than expected in rural areas may reflect different perceptions or differing patterns of illness. The stronger relations between the three proxies in urban than rural areas suggests that the choice of indicator will have less impact in urban than rural areas and strengthens the argument to develop better measures of health care need in rural areas
A UK-based cost-utility analysis of radiofrequency ablation or oesophagectomy for the management of high-grade dysplasia in Barrett's oesophagus
No full textBackground: in the UK, oesophagectomy is the current recommendation for patients with persistent high-grade dysplasia in Barrett’s oesophagus. Radiofrequency ablation is an alternative new technology with promising early trial results.Aim: to undertake a cost–utility analysis comparing these two strategies.Methods: we constructed a Markov model to simulate the natural history of a cohort of patients with high-grade dysplasia in Barrett’s oesophagus undergoing one of two treatment options: (i) oesophagectomy or (ii) radiofrequency ablation followed by endoscopic surveillance with oesophagectomy for high-grade dysplasia recurrence or persistence.Results: in the base case analysis, radiofrequency ablation dominated as it generated 0.4 extra quality of life years at a cost saving of £1902. For oesophagectomy to be the most cost-effective option, it required a radiofrequency ablation treatment failure rate (high-grade dysplasia persistence or progression to cancer) of >44%, or an annual risk of high-grade dysplasia recurrence or progression to cancer in the ablated oesophagus of >15% per annum. There was an 85% probability that radiofrequency ablation remained cost-effective at the NICE willingness to pay threshold range of £20 000–30 000.Conclusion: radiofrequency ablation is likely to be a cost-effective option for high-grade dysplasia in Barrett’s oesophagus in the UK.<br/
APPENDIX_-_UNSAFE_LIST_26_11_19_suppl_material – Supplemental material for King’s College London’s enquiry into Hans J Eysenck’s ‘Unsafe’ publications must be properly completed
No full textSupplemental material, APPENDIX_-_UNSAFE_LIST_26_11_19_suppl_material for King’s College London’s enquiry into Hans J Eysenck’s ‘Unsafe’ publications must be properly completed by David F Marks and Roderick D Buchanan in Journal of Health Psychology</p
Use of a coronary heart disease simulation model to evaluate the costs and effectiveness of drugs for the prevention of heart disease
No full textA discrete event simulation model of the patient pathways in the treatment of coronary heart disease (CHD) was used to quantify the health gains and costs associated with increasing secondary prevention drugs prescription for patients with CHD based on the level recommended in the National Service Framework for the UK. A Gompertz distribution was sampled for time to failure ( death or non-fatal heart attack). The time to failure was modified in relation to the reduced risk of failure for those on the relevant drugs. The results from the model were validated against national data. Increasing the levels of prescription of secondary prevention drugs to those patients with CHD might prevent 100 deaths per million population per year and cost an additional 4 pound million per million population per year. With cost per life year saved of 5520 pound, this appears good value for money compared with other health technologies
The study of infectious intestinal disease in England: socio-economic impact
No full textTo assess the socio-economic impact of infectious intestinal disease (IID) on the health care sector, cases and their families, cases of IID ascertained from a population cohort component and those presenting to general practices were sent a socio-economic questionnaire 3 weeks after the acute episode. The impact of the illness was measured and the resources used were identified and costed. The duration, severity and costs of illness linked to viruses were less than those linked to bacteria. The average cost per case of IID presenting to the GP was £253 and the costs of those not seeing a GP were £34. The average cost per case was £606 for a case with salmonella, £315 for campylobacter, £164 for rotavirus and £176 for SRSV. The estimated cost of IID in England was £743m expressed in 1994/5 prices. The costs of IID are considerable and the duration of the illness was found to be longer than previous reports have suggested
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