1,062 research outputs found
The use of statistical methodology to determine the accuracy of grading within a diabetic retinopathy screening programme
No full textAIMS:
We aimed to use longitudinal data from an established screening programme with good quality assurance and quality control procedures and a stable well-trained workforce to determine the accuracy of grading in diabetic retinopathy screening.
METHODS:
We used a continuous time-hidden Markov model with five states to estimate the probability of true progression or regression of retinopathy and the conditional probability of an observed grade given the true grade (misclassification). The true stage of retinopathy was modelled as a function of the duration of diabetes and HbA1c .
RESULTS:
The modelling dataset consisted of 65 839 grades from 14 187 people. The median number [interquartile range (IQR)] of examinations was 5 (3, 6) and the median (IQR) interval between examinations was 1.04 (0.99, 1.17) years. In total, 14 227 grades (21.6%) were estimated as being misclassified, 10 592 (16.1%) represented over-grading and 3635 (5.5%) represented under-grading. There were 1935 (2.9%) misclassified referrals, 1305 were false-positive results (2.2%) and 630 were false-negative results (11.0%). Misclassification of background diabetic retinopathy as no detectable retinopathy was common (3.4% of all grades) but rarely preceded referable maculopathy or retinopathy.
CONCLUSION:
Misclassification between lower grades of retinopathy is not uncommon but is unlikely to lead to significant delays in referring people for sight-threatening retinopathy
A prospective study of urinary androgen levels and ovarian cancer
No full textThe three major urinary androgen metabolites, dehydroepiandrosterone (DHEA), androsterone (ANDRO), and aetiocholanolone (AETIO) were measured in 1,484 volunteer women between 29 and 60 years of age on the island of Guernsey from 1962–1967. Twelve of these women subsequently developed ovarian cancer after a median interval of 130 months and a minimum interval of 19 months. All three androgen levels in these women were lower than those in controls matched for age and menopausal status. The results were most striking for DHEA, where half of the cases were below the 27th percentile of their matched controls (p = 0.007, two‐sided). The results for ANDRO were of marginal significance (p = 0.06), and those for AETIO were not significant (p= 0.033).</p
Development of a cost-effectiveness model for optimisation of the screening interval in diabetic retinopathy screening
No full textBACKGROUND:
The English NHS Diabetic Eye Screening Programme was established in 2003. Eligible people are invited annually for digital retinal photography screening. Those found to have potentially sight-threatening diabetic retinopathy (STDR) are referred to surveillance clinics or to Hospital Eye Services.
OBJECTIVES:
To determine whether personalised screening intervals are cost-effective.
DESIGN:
Risk factors were identified in Gloucestershire, UK using survival modelling. A probabilistic decision hidden (unobserved) Markov model with a misgrading matrix was developed. This informed estimation of lifetime costs and quality-adjusted life-years (QALYs) in patients without STDR. Two personalised risk stratification models were employed: two screening episodes (SEs) (low, medium or high risk) or one SE with clinical information (low, medium-low, medium-high or high risk). The risk factor models were validated in other populations.
SETTING:
Gloucestershire, Nottinghamshire, South London and East Anglia (all UK).
PARTICIPANTS:
People with diabetes in Gloucestershire with risk stratification model validation using data from Nottinghamshire, South London and East Anglia.
MAIN OUTCOME MEASURES:
Personalised risk-based algorithm for screening interval; cost-effectiveness of different screening intervals.
RESULTS:
Data were obtained in Gloucestershire from 12,790 people with diabetes with known risk factors to derive the risk estimation models, from 15,877 people to inform the uptake of screening and from 17,043 people to inform the health-care resource-usage costs. Two stratification models were developed: one using only results from previous screening events and one using previous screening and some commonly available GP data. Both models were capable of differentiating groups at low and high risk of development of STDR. The rate of progression to STDR was 5 per 1000 person-years (PYs) in the lowest decile of risk and 75 per 1000 PYs in the highest decile. In the absence of personalised risk stratification, the most cost-effective screening interval was to screen all patients every 3 years, with a 46% probability of this being cost-effective at a £30,000 per QALY threshold. Using either risk stratification models, screening patients at low risk every 5 years was the most cost-effective option, with a probability of 99-100% at a £30,000 per QALY threshold. For the medium-risk groups screening every 3 years had a probability of 43-48% while screening high-risk groups every 2 years was cost-effective with a probability of 55-59%.
CONCLUSIONS:
The study found that annual screening of all patients for STDR was not cost-effective. Screening this entire cohort every 3 years was most likely to be cost-effective. When personalised intervals are applied, screening those in our low-risk groups every 5 years was found to be cost-effective. Screening high-risk groups every 2 years further improved the cost-effectiveness of the programme. There was considerable uncertainty in the estimated incremental costs and in the incremental QALYs, particularly with regard to implications of an increasing proportion of maculopathy cases receiving intravitreal injection rather than laser treatment. Future work should focus on improving the understanding of risk, validating in further populations and investigating quality issues in imaging and assessment including the potential for automated image grading
Responding to the Threat of Violent Extremism - Failing to Prevent
No full textThe shocking 7/7 London bombings and subsequent plots have confirmed the Islamist terrorist threat faced by the UK. How should we understand such home-grown terrorism, and how successful since 2005 have government attempts to ‘prevent violent extremism’ through community-based education been? This 2012 monograph draws on research evidence, much of it from work with young people in the north of England, to suggest that the 'Prevent' policy approaches have been misguided and ineffective, further alienating British Muslim communities rather than supporting longer-term attempts to encourage community cohesion and integration that provides resilience against extremism
Theoretical studies of the historical development of the accounting discipline: a review and evidence
No full textMany existing studies of the development of accounting thought have either been atheoretical or have adopted Kuhn's model of scientific growth. The limitations of this 35-year-old model are discussed. Four different general neo-Kuhnian models of scholarly knowledge development are reviewed and compared with reference to an analytical matrix. The models are found to be mutually consistent, with each focusing on a different aspect of development. A composite model is proposed. Based on a hand-crafted database, author co-citation analysis is used to map empirically the entire literature structure of the accounting discipline during two consecutive time periods, 1972–81 and 1982–90. The changing structure of the accounting literature is interpreted using the proposed composite model of scholarly knowledge development
Editorial Board
No full textEditor-in Chief Laurence E. Eck Associate Editors Alan F. Cain Gary L. Graham Thomas A. Harney Douglas M. Greenwood Peter M. Kirwan Hames P. Murphy, Jr. Staff Edward Bartlett John L. Hilts Richard G. Nollmeyer, M.D. James L. Jones Carl Roehl William P. Roscoe III Rex B. Stratton, III Faculty Advisor Larry M. Eliso
Hippocampal activation for autobiographical memories over the entire lifetime in healthy aged subjects: An fMRI study
No full textInternational audienceWe used functional magnetic resonance imaging to determine the cerebral structures required during the recollection of episodic autobiographical memories according to 5 time periods covering the whole lifespan to test the 2 concurring models of memory consolidation, which propose either a temporary (standard model) or a permanent (multiple-trace model) role of the hippocampus in episodic memory retrieval. The experimental paradigm was specially designed to engage subjects (67.17 +/- 5.22 years old) in the retrieval of episodic autobiographical memories, whatever the time period, from personally relevant cues selected by questioning a family member. Moreover, the nature of the memories was checked at debriefing by means of behavioral measures to control the degree of episodicity. Behavioral data showed that recollected memories were characterized by specificity and details whatever their remoteness. Main neuroimaging data (Statistical Parametric Mapping 99) revealed the activation of a network including the left superior frontal gyri, bilateral precuneus/posterior cingulate and lingual gyri, left angular gyrus, and left hippocampus, although the subtraction analyses detected subtle differences between certain time periods. Small volume correction centered on the hippocampus detected left hippocampal activation for all time periods and additional right hippocampal activation for the intermediate periods. Further confirmation was provided by using a 3-way analysis of variance on blood oxygen level-dependent values, which revealed hippocampal activation whatever the time interval. The present data challenge the standard model of memory consolidation and support the multiple-trace model, instead. The comparison with previous literature stresses the idea that a bilateral involvement of the hippocampus characterizes rich episodic autobiographical memory recollection
Managing the trade-off implications of global supply
No full textThe cost versus response trade-off is a growing logistics issue due to many markets being increasingly characterized by demand uncertainty and shorter product life cycles. This is exacerbated further with supply increasingly moving to low cost global sources. However, the poor response implications of global supply are often not addressed or even acknowledged when undertaking such decisions. Consequently, various practical approaches to minimising, postponing or otherwise managing the impact of the demand uncertainty are often only adopted retrospectively. Even though such generic solutions are documented through case examples we lack effective tools and concepts to support the proactive identification and resolution of such trade-offs. This paper reports on case-based theory building research, involving three cases from the UK and USA used in developing a conceptual model with associated tools, in support of such a process
Interview: Anne-Marie Fortier
No full textThis paper is an edited version of an email interview conducted by Debra Ferreday and Adi Kuntsman with Anne-Marie Fortier, the author of Multicultural Horizons: Diversity and the Limits of the Civil Nation (Routledge, 2008). Fortier’s work has been informative in the development of some of the arguments explored in this special issue; in their conversation Ferreday and Kuntsman asked her to comment on the ideas of haunting, racial imaginaries, nostalgia, national anxieties, political feelings and hopes for the future
- …
