Target Conditions (target + condition)

Distribution by Scientific Domains


Selected Abstracts


Bayes' Theorem to estimate population prevalence from Alcohol Use Disorders Identification Test (AUDIT) scores

ADDICTION, Issue 7 2009
David R. Foxcroft
ABSTRACT Aim The aim in this methodological paper is to demonstrate, using Bayes' Theorem, an approach to estimating the difference in prevalence of a disorder in two groups whose test scores are obtained, illustrated with data from a college student trial where 12-month outcomes are reported for the Alcohol Use Disorders Identification Test (AUDIT). Method Using known population prevalence as a background probability and diagnostic accuracy information for the AUDIT scale, we calculated the post-test probability of alcohol abuse or dependence for study participants. The difference in post-test probability between the study intervention and control groups indicates the effectiveness of the intervention to reduce alcohol use disorder rates. Findings In the illustrative analysis, at 12-month follow-up there was a mean AUDIT score difference of 2.2 points between the intervention and control groups: an effect size of unclear policy relevance. Using Bayes' Theorem, the post-test probability mean difference between the two groups was 9% (95% confidence interval 3,14%). Interpreted as a prevalence reduction, this is evaluated more easily by policy makers and clinicians. Conclusion Important information on the probable differences in real world prevalence and impact of prevention and treatment programmes can be produced by applying Bayes' Theorem to studies where diagnostic outcome measures are used. However, the usefulness of this approach relies upon good information on the accuracy of such diagnostic measures for target conditions. [source]


Experimental investigation of the intermediates of isooctane during ignition

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2007
X. He
Direct measurements of intermediates of ignition are challenging experimental objectives, yet such measurements are critical for understanding fuel decomposition and oxidation pathways. In the current work, a new gas-sampling system is used to provide quantitative discrete measurements of 30 hydrocarbon and oxygenate species during rapid compression facility studies of isooctane ignition. Two target conditions and equivalence ratios (based on molar fuel to oxygen ratio) were studied (P = 5.2 atm, T = 1000 K, , = 0.4 and P = 4.8 atm, T = 975 K, , = 1.2). The results are compared with model predictions that use the detailed reaction mechanism developed by Curran et al. (Combust Flame 2002, 129, 253,280). In general, the model predictions are in excellent agreement with the experimental data, including several trace species. Isobutene (i-C4H8) and propene (C3H6) were the major olefin species identified in the experiments. The results are consistent with an intermediate temperature reaction path sequence, where isooctane is consumed by H-atom abstraction to yield isooctyl radicals that undergo ,-scission to form olefin and alkyl radical species. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 498,517, 2007 [source]


Vision screening of older people

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2007
Zahra Jessa
Abstract A recent systematic review found that between 20% and 50% of older people in the UK have undetected reduced vision and in most cases this is caused by refractive error or cataracts, and is correctable. Two approaches to improve the detection of these problems are to better publicise optometric services and to carry out community-based vision screening of older people. Screening programmes should pass the Wilson criteria and a consideration of these highlights three inter-related questions: ,Is vision screening effective at detecting correctable low vision in older people?'; ,Which tests should be included?' and ,Which venues are most appropriate?' We carried out a systematic review to investigate these questions. For the first question, only one study was found which met our selection criteria. The ,gold standard' eye examination in this study lacked several important components, and the vision screening method that was used was not found to be very effective. The review revealed other studies, which, although not meeting our selection criteria, included relevant information. The screening studies highlight the lack of agreement on the content of a gold standard eye examination and of the test(s) that should be used to screen vision. Visual function in older people is not adequately described by high contrast visual acuity (VA), nor by self-reports of visual difficulties. Other tests that may be relevant include visual field testing, low contrast VA, contrast sensitivity and stereo-acuity. The pinhole test has often been used in attempts to detect uncorrected refractive errors, but results from this test can be problematic and possible reasons for this are discussed. Appropriate venues for vision screening are contingent upon the format of the vision screening programme. There is still uncertainty over the battery of vision tests that are most appropriate. This, and optimum venues for screening, require further research before it can be fully determined whether vision screening of older people meets the Wilson criteria. If a vision screening programme using a battery of vision tests, perhaps computerised, can be established, then this should be tested to determine the sensitivity and specificity for detecting the target conditions. Ultimately, longitudinal studies are necessary to determine whether such a screening programme will lead to improved visual performance and quality of life in older people. [source]


Ophthalmological follow-up at 2 years of age of all children previously screened for retinopathy of prematurity: is it worthwhile?

ACTA OPHTHALMOLOGICA, Issue 5 2006
Anna-Lena Hård
Abstract. Purpose:, To evaluate the extent to which ophthalmological follow-up at 2 years of age of children born before 32 weeks gestation identifies obvious visual problems, strabismus and significant ametropia (target conditions). Methods:, Of 172 children born during a period of 2.5 years from January 2000, 142 underwent an ophthalmological examination at a median age of 2.33 years. This included evaluation of visual behaviour, cover testing and autorefractometry in cycloplegia. For children with the target conditions, we investigated whether the child had been followed in the eye clinic or referred before 2 years of age, or whether the abnormality was detected as a result of the follow-up examination. Results:, None of the target conditions were found in 117 children. None of four children with obviously abnormal visual behaviour, two of 10 children with strabismus and four of 11 with large refractive errors were detected in the follow-up examination. Thus the target conditions were detected at the follow-up examination in only six of 142 children (4.2%). Conclusions:, Although ophthalmic abnormalities are common in children born prematurely, most of them are identified because high-risk children are followed regularly in eye clinics and because parents and primary health care personnel detect strabismus. Ophthalmological follow-up of all children born before 32 weeks appears not to be worthwhile and is therefore only recommended for high-risk children. [source]