Evaluation of screening tests for predicting older driver performance and safety assessed by an on-road test

A number of tests and test batteries are available for the prediction of older driver safety, but many of these have not been validated against standardized driving outcome measures. The aim of this study was to evaluate a series of previously described screening tests in terms of their ability to predict the potential for safe and unsafe driving. Participants included 79 community-dwelling older drivers (M=72.16 years, SD=5.46; range 65-88 years; 57 males and 22 females) who completed a previously validated multi-disciplinary driving assessment, a hazard perception test, a hazard change detection test and a battery of vision and cognitive tests. Participants also completed a standardized on-road driving assessment. The multi-disciplinary test battery had the highest predictive ability with a sensitivity of 80% and a specificity of 73%, followed by the hazard perception test which demonstrated a sensitivity of 75% and a specificity of 61%. These findings suggest that a relatively simple and practical battery of tests from a range of domains has the capacity to predict safe and unsafe driving in older adults.

Screening tests for detecting open-angle glaucoma: systematic review and meta-analysis

PURPOSE: To assess the comparative accuracy of potential screening tests for open angle glaucoma (OAG).

METHODS: Medline, Embase, Biosis (to November 2005), Science Citation Index (to December 2005), and The Cochrane Library (Issue 4, 2005) were searched. Studies assessing candidate screening tests for detecting OAG in persons older than 40 years that reported true and false positives and negatives were included. Meta-analysis was undertaken using the hierarchical summary receiver operating characteristic model.

RESULTS: Forty studies enrolling over 48,000 people reported nine tests. Most tests were reported by only a few studies. Frequency-doubling technology (FDT; C-20-1) was significantly more sensitive than ophthalmoscopy (30, 95% credible interval [CrI] 0-62) and Goldmann applanation tonometry (GAT; 45, 95% CrI 17-68), whereas threshold standard automated perimetry (SAP) and Heidelberg Retinal Tomograph (HRT II) were both more sensitive than GAT (41, 95% CrI 14-64 and 39, 95% CrI 3-64, respectively). GAT was more specific than both FDT C-20-5 (19, 95% CrI 0-53) and threshold SAP (14, 95% CrI 1-37). Judging performance by diagnostic odds ratio, FDT, oculokinetic perimetry, and HRT II are promising tests. Ophthalmoscopy, SAP, retinal photography, and GAT had relatively poor performance as single tests. These findings are based on heterogeneous data of limited quality and as such are associated with considerable uncertainty.

CONCLUSIONS: No test or group of tests was clearly superior for glaucoma screening. Further research is needed to evaluate the comparative accuracy of the most promising tests.

Comparison between 100-g glucose tolerance test and two other screening tests for gestational diabetes: combined fasting glucose with risk factors and 50-g glucose tolerance test

CONTEXTO E OBJETIVO: A falta de consenso sobre os protocolos de rastreamento e diagnóstico do diabetes gestacional, associada às dificuldades na realização do teste oral simplificado do diabete gestacional (o teste de tolerância a 100 g de glicose, considerado padrão-ouro) justificam a comparação com alternativas. O objetivo deste trabalho é comparar o teste padrão-ouro a dois testes de rastreamento: associação de glicemia de jejum e fatores de risco (GJ + FR) e o teste oral simplificado de tolerância a 50 g de glicose (TTG 50 g), com o teste de tolerância a 100 g de glicose (TTG 100 g). TIPO DE ESTUDO E LOCAL: Estudo de coorte longitudinal, prospectivo, realizado no Serviço de Ginecologia e Obstetrícia do Hospital Universitário da Universidade Federal de Mato Grosso do Sul. MÉTODOS: 341 gestantes foram submetidas aos três testes. Calcularam-se os índices de sensibilidade (S), especificidade (E), valores preditivos (VPP e VPN), razões de probabilidade (RPP e RPN) e resultados falsos (FP e FN), positivos e negativos da associação GJ + FR e do TTG 50 g em relação ao TTG 100 g. Compararam-se as médias das glicemias de uma hora pós-sobrecarga (1hPS) com 50 e 100 g. Na análise estatística, empregou-se o teste t de Student, com limite de significância de 5%. RESULTADOS: A associação GJ + FR encaminhou mais gestantes (53,9%) para a confirmação diagnóstica que o TTG 50 g (14,4%). Os dois testes foram equivalentes nos índices de S (86,4 e 76,9%), VPN (98,7 e 98,9%), RPN (0,3 e 0,27) e FN (15,4 e 23,1%). As médias das glicemias 1hPS foram semelhantes, 106,8 mg/dl para o TTG 50 g e 107,5 mg/dl para o TTG 100 g. CONCLUSÕES: Os resultados da eficiência diagnóstica associados à simplicidade, praticabilidade e custo referendaram a associação GJ + FR como o mais adequado para o rastreamento. A equivalência das glicemias de 1hPS permitiram a proposição de um novo protocolo de rastreamento e diagnóstico do diabete gestacional, com menores custo e desconforto.

Field performance of two rapid screening tests in active surveillance of transmissible spongiform encephalopathies in small ruminants

Recently, screening tests for monitoring the prevalence of transmissible spongiform encephalopathies specifically in sheep and goats became available. Although most countries require comprehensive test validation prior to approval, little is known about their performance under normal operating conditions. Switzerland was one of the first countries to implement 2 of these tests, an enzyme-linked immunosorbent assay (ELISA) and a Western blot, in a 1-year active surveillance program. Slaughtered animals (n = 32,777) were analyzed in either of the 2 tests with immunohistochemistry for confirmation of initial reactive results, and fallen stock samples (n = 3,193) were subjected to both screening tests and immunohistochemistry in parallel. Initial reactive and false-positive rates were recorded over time. Both tests revealed an excellent diagnostic specificity (>99.5%). However, initial reactive rates were elevated at the beginning of the program but dropped to levels below 1% with routine and enhanced staff training. Only those in the ELISA increased again in the second half of the program and correlated with the degree of tissue autolysis in the fallen stock samples. It is noteworthy that the Western blot missed 1 of the 3 atypical scrapie cases in the fallen stock, indicating potential differences in the diagnostic sensitivities between the 2 screening tests. However, an estimation of the diagnostic sensitivity for both tests on field samples remained difficult due to the low disease prevalence. Taken together, these results highlight the importance of staff training, sample quality, and interlaboratory comparison trials when such screening tests are implemented in the field.

Results of screening tests with materials evaluated as insecticides, miticides, and repellents at the Orlando, Fla., laboratory, April 1942 to April 1947.

Processed.

A capture–recapture approach for screening using two diagnostic tests with availability of disease status for the test positives only

The article considers screening human populations with two screening tests. If any of the two tests is positive, then full evaluation of the disease status is undertaken; however, if both diagnostic tests are negative, then disease status remains unknown. This procedure leads to a data constellation in which, for each disease status, the 2 × 2 table associated with the two diagnostic tests used in screening has exactly one empty, unknown cell. To estimate the unobserved cell counts, previous approaches assume independence of the two diagnostic tests and use specific models, including the special mixture model of Walter or unconstrained capture–recapture estimates. Often, as is also demonstrated in this article by means of a simple test, the independence of the two screening tests is not supported by the data. Two new estimators are suggested that allow associations of the screening test, although the form of association must be assumed to be homogeneous over disease status. These estimators are modifications of the simple capture–recapture estimator and easy to construct. The estimators are investigated for several screening studies with fully evaluated disease status in which the superior behavior of the new estimators compared to the previous conventional ones can be shown. Finally, the performance of the new estimators is compared with maximum likelihood estimators, which are more difficult to obtain in these models. The results indicate the loss of efficiency as minor.

A capture-recapture approach for screening using two diagnostic tests with availability of disease status for the test positives only

The article considers screening human populations with two screening tests. If any of the two tests is positive, then full evaluation of the disease status is undertaken; however, if both diagnostic tests are negative, then disease status remains unknown. This procedure leads to a data constellation in which, for each disease status, the 2 x 2 table associated with the two diagnostic tests used in screening has exactly one empty, unknown cell. To estimate the unobserved cell counts, previous approaches assume independence of the two diagnostic tests and use specific models, including the special mixture model of Walter or unconstrained capture-recapture estimates. Often, as is also demonstrated in this article by means of a simple test, the independence of the two screening tests is not supported by the data. Two new estimators are suggested that allow associations of the screening test, although the form of association must be assumed to be homogeneous over disease status. These estimators are modifications of the simple capture-recapture estimator and easy to construct. The estimators are investigated for several screening studies with fully evaluated disease status in which the superior behavior of the new estimators compared to the previous conventional ones can be shown. Finally, the performance of the new estimators is compared with maximum likelihood estimators, which are more difficult to obtain in these models. The results indicate the loss of efficiency as minor.

Clinical utility of mental state screening as a predictor of intellectual outcomes 6 months after diagnosis of type 1 diabetes

Background Screening tests of basic cognitive status or ‘mental state’ have been shown to predict mortality and functional outcomes in adults. This study examined the relationship between mental state and outcomes in children with type 1 diabetes. Objective We aimed to determine whether mental state at diagnosis predicts longer term cognitive function of children with a new diagnosis of type 1 diabetes. Methods Mental state of 87 patients presenting with newly diagnosed type 1 diabetes was assessed using the School-Years Screening Test for the Evaluation of Mental Status. Cognitive abilities were assessed 1 wk and 6 months postdiagnosis using standardized tests of attention, memory, and intelligence. Results Thirty-seven children (42.5%) had reduced mental state at diagnosis. Children with impaired mental state had poorer attention and memory in the week following diagnosis, and, after controlling for possible confounding factors, significantly lower IQ at 6 months compared to those with unimpaired mental state (p < 0.05). Conclusions Cognition is impaired acutely in a significant number of children presenting with newly diagnosed type 1 diabetes. Mental state screening is an effective method of identifying children at risk of ongoing cognitive difficulties in the days and months following diagnosis. Clinicians may consider mental state screening for all newly diagnosed diabetic children to identify those at risk of cognitive sequelae.

Commercial-scale Alternaria brown spot resistance screening as the first step in breeding new mandarins for Australia

Rapid screening tests and an appreciation of the simple genetic control of Alternaria brown spot (ABS) susceptibility have existed for many years, and yet the application of this knowledge to commercial-scale breeding programs has been limited. Detached leaf assays were first demonstrated more than 40 years ago and reliable data suggesting a single gene determining susceptibility has been emerging for at least 20 years. However it is only recently that the requirement for genetic resistance in new hybrids has become a priority, following increased disease prevalence in Australian mandarin production areas previously considered too dry for the pathogen. Almost all of the high-fruit-quality parents developed so far by the Queensland-based breeding program are susceptible to ABS necessitating the screening of their progeny to avoid commercialisation of susceptible hybrids. This is done effectively and efficiently by spraying 3-6 month old hybrid seedlings with a spore suspension derived from a toxin-producing field isolate of Alternaria alternate, then incubating these seedlings in a cool room at 25°C and high humidity for 5 days. Susceptible seedlings show clear disease symptoms and are discarded. Analysis of observed and expected segregation ratios loosely support the hypothesis for a single dominant gene for susceptibility, but do not rule out the possibility of alternative genetic models. After implementing the routine screening for ABS resistance for three seasons we now have more than 20,000 hybrids growing in field progeny blocks that have been screened for resistance to the ABS disease.

Repeated measures screening for down's syndrome

Objective To demonstrate the potential value of screening for Down's Syndrome using highly correlated repeated measures of serum markers taken in the first and second trimesters of pregnancy. Design A Monte Carlo simulation study. Population Detection rates and false positive rates relating to the maternal age distribution of England and Wales for the period 1996 to 1998 were obtained using marker distributions from the SURUSS study. Results Screening using first trimester nuchal translucency and repeated measures of uE3 and PAPP-A in the first and second trimester has an estimated false positive rate of 0.3% for an 85% detection rate. This should be compared with the integrated test with an estimated false positive rate of 1.2% for the same detection rate. Conclusionsâ?? The performance of repeated measures screening tests, and their acceptability to women, should be assessed in further prospective studies.

Exploring the perspective of midwives involved in offering serum screening for Down's syndrome in Northern Ireland

Aims. To explore the perspective of midwives offering serum screening for Down’s syndrome.

Background. Previous literature has indicated that the offer and discussion of prenatal serum screening tests with women is complex, and health professionals may influence women’s decisions to accept or decline screening. Midwives are usually the key professional to offer serum screening for Down’s syndrome in the UK but their perspective is relatively neglected in the literature.

Design. An explorative qualitative interview study with 15 midwives employed in a maternity unit in Northern Ireland involved in offering prenatal screening to pregnant women. Data were collected from 1 July 2005–31 October 2005.

Methods. A focused ethnographic approach was used to explore the perspective of midwives.

Results. Midwives reported difficulty in explaining the test to women and felt unable to provide the necessary information to adequately inform women within their appointment time. The test offered (the triple test) and potential pathway of subsequent care, were identified as sources of professional and personal conflict by midwives. The expectation that midwives would provide a universal offer of Down’s syndrome serum screening but be unable to support women regarding termination of pregnancy also created dissonance.

Conclusions. The feasibility of proceeding with a universal serum screening programme for Down’s syndrome is questionable in countries which legally or culturally oppose termination of pregnancy. Professionals practising within environments such as this experience conflict in their role, which affects communication with women when discussing screening tests.

Relevance to clinical practice. As midwives are often, the primary health professional providing information to women, it is important that midwives are key participants in ongoing planning and discussions about screening policy to ensure programmes are implemented successfully.

Developing the specifications of an open angle glaucoma screening intervention in the United Kingdom: a Delphi approach.

Abstract
BACKGROUND:
Glaucoma is a leading cause of blindness. Early detection is advocated but there is insufficient evidence from randomized controlled trials (RCTs) to inform health policy on population screening. Primarily, there is no agreed screening intervention. For a screening programme, agreement is required on the screening tests to be used, either individually or in combination, the person to deliver the test and the location where testing should take place. This study aimed to use ophthalmologists (who were experienced glaucoma subspecialists), optometrists, ophthalmic nurses and patients to develop a reduced set of potential screening tests and testing arrangements that could then be explored in depth in a further study of their feasibility for evaluation in a glaucoma screening RCT.
METHODS:
A two-round Delphi survey involving 38 participants was conducted. Materials were developed from a prior evidence synthesis. For round one, after some initial priming questions in four domains, specialists were asked to nominate three screening interventions, the intervention being a combination of the four domains; target population, (age and higher risk groups), site, screening test and test operator (provider). More than 250 screening interventions were identified. For round two, responses were condensed into 72 interventions and each was rated by participants on a 0-10 scale in terms of feasibility.
RESULTS:
Using a cut-off of a median rating of feasibility of =5.5 as evidence of agreement of intervention feasibility, six interventions were identified from round 2. These were initiating screening at age 50, with a combination of two or three screening tests (varying combinations of tonometry/measures of visual function/optic nerve damage) organized in a community setting with an ophthalmic trained technical assistant delivering the tests. An alternative intervention was a 'glaucoma risk score' ascertained by questionnaire. The advisory panel recommended that further exploration of the feasibility of screening higher risk populations and detailed specification of the screening tests was required.
CONCLUSIONS:
With systematic use of expert opinions, a shortlist of potential screening interventions was identified. Views of users, service providers and cost-effectiveness modeling are now required to identify a feasible intervention to evaluate in a future glaucoma screening trial.

The clinical effectiveness and cost-effectiveness of screening for open angle glaucoma:A systematic review and economic evaluation

Objectives: To assess whether open angle glaucoma (OAG) screening meets the UK National Screening Committee criteria, to compare screening strategies with case finding, to estimate test parameters, to model estimates of cost and cost-effectiveness, and to identify areas for future research. Data sources: Major electronic databases were searched up to December 2005. Review methods: Screening strategies were developed by wide consultation. Markov submodels were developed to represent screening strategies. Parameter estimates were determined by systematic reviews of epidemiology, economic evaluations of screening, and effectiveness (test accuracy, screening and treatment). Tailored highly sensitive electronic searches were undertaken. Results: Most potential screening tests reviewed had an estimated specificity of 85% or higher. No test was clearly most accurate, with only a few, heterogeneous studies for each test. No randomised controlled trials (RCTs) of screening were identified. Based on two treatment RCTs, early treatment reduces the risk of progression. Extrapolating from this, and assuming accelerated progression with advancing disease severity, without treatment the mean time to blindness in at least one eye was approximately 23 years, compared to 35 years with treatment. Prevalence would have to be about 3-4% in 40 year olds with a screening interval of 10 years to approach cost-effectiveness. It is predicted that screening might be cost-effective in a 50-year-old cohort at a prevalence of 4% with a 10-year screening interval. General population screening at any age, thus, appears not to be cost-effective. Selective screening of groups with higher prevalence (family history, black ethnicity) might be worthwhile, although this would only cover 6% of the population. Extension to include other at-risk cohorts (e.g. myopia and diabetes) would include 37% of the general population, but the prevalence is then too low for screening to be considered cost-effective. Screening using a test with initial automated classification followed by assessment by a specialised optometrist, for test positives, was more cost-effective than initial specialised optometric assessment. The cost-effectiveness of the screening programme was highly sensitive to the perspective on costs (NHS or societal). In the base-case model, the NHS costs of visual impairment were estimated as £669. If annual societal costs were £8800, then screening might be considered cost-effective for a 40-year-old cohort with 1% OAG prevalence assuming a willingness to pay of £30,000 per quality-adjusted life-year. Of lesser importance were changes to estimates of attendance for sight tests, incidence of OAG, rate of progression and utility values for each stage of OAG severity. Cost-effectiveness was not particularly sensitive to the accuracy of screening tests within the ranges observed. However, a highly specific test is required to reduce large numbers of false-positive referrals. The findings that population screening is unlikely to be cost-effective are based on an economic model whose parameter estimates have considerable uncertainty, in particular, if rate of progression and/or costs of visual impairment are higher than estimated then screening could be cost-effective. Conclusions: While population screening is not cost-effective, the targeted screening of high-risk groups may be. Procedures for identifying those at risk, for quality assuring the programme, as well as adequate service provision for those screened positive would all be needed. Glaucoma detection can be improved by increasing attendance for eye examination, and improving the performance of current testing by either refining practice or adding in a technology-based first assessment, the latter being the more cost-effective option. This has implications for any future organisational changes in community eye-care services. Further research should aim to develop and provide quality data to populate the economic model, by conducting a feasibility study of interventions to improve detection, by obtaining further data on costs of blindness, risk of progression and health outcomes, and by conducting an RCT of interventions to improve the uptake of glaucoma testing. © Queen's Printer and Controller of HMSO 2007. All rights reserved.