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Biomedical subjects

K Bassett

Publications and source records attributed to K Bassett.

16 recordsLinked to original sources
PubMed2006

Contrast sensitivity and visual hallucinations in patients referred to a low vision rehabilitation clinic.

AIM: To examine the association of reported visual hallucinations and measured visual parameters in adult patients referred for low vision rehabilitation. METHODS: All patients (N = 225) referred to a low vision rehabilitation clinic for a calendar year were asked a standardised question about symptoms of formed visual hallucinations. Best corrected visual acuity and contrast sensitivity using the Pelli-Robson chart were measured. We conducted multiple logistic regression analysis of the association between visual hallucinations and visual parameters. RESULTS: Of the total cohort, 78 (35%) reported visual hallucinations. Visual acuity and contrast sensitivity were considered in four quartiles. In multiple logistic regression controlling for contrast sensitivity, age, gender, report of depression and independence, measured acuity in each of the poorer three categories (compared to the best) was not associated with reported hallucinations. Contrast sensitivity in the three poorer quartiles (compared to the best) was strongly associated with the report of hallucinations (OR 4.1, CI 1.1, 15.9; OR 10.5, CI 2.6, 42.1; OR 28.1, CI 5.6, 140.9) after controlling for acuity, age, sex, depression and independence. CONCLUSIONS: Lowest contrast sensitivity was the strongest predictor of reported hallucinations after adjusting for visual acuity.

Aged↗
PubMed2006

The prevalence of low vision and blindness in Canada.

PURPOSE: The purpose of this study was to ascertain the prevalence and primary causes of visual impairment in a representative Canadian population. METHODS: We reviewed a representative sample of patients who attended ophthalmologists' offices in a medium-sized Canadian city between 1996 and 2001 in order to estimate the prevalence of visual impairment. Demographic data, visual diagnoses, best-corrected visual acuities (BCVA), and visual field information were recorded. Visual status was categorized based on accepted World Health Organization (WHO) and North American criteria. Population data were obtained from the Canadian census. RESULTS: The prevalence of low vision and blindness in our population was 35.6 and 3.8 per 10 000 individuals, according to the WHO classification, and 71.2 and 23.6 per 10 000 individuals, using the North American definition. Among individuals with some vision loss (vision worse than 20/40), cataract and visual pathway disease were the most common causes, together accounting for 40% of visual impairment. Age-related macular degeneration and other retinal diseases were the next most common causes of vision loss. Diabetic retinopathy and glaucoma were less frequently encountered as causes of visual impairment. CONCLUSION: The overall prevalence of low vision and blindness in Canada are in keeping with data from large population-based studies from other developed nations. Cataract, visual pathway disease, and macular degeneration are the leading causes of visual impairment. These results are important for enhancing our understanding of the scope of vision health in Canada and may direct future health planning and cost-utilization research.

Adolescent↗
PubMed2001

Gender and blindness: a meta-analysis of population-based prevalence surveys.

BACKGROUND: Many individual surveys of blindness have reported slightly higher rates of blindness for women. In order to gain a continent-by-continent and global sense of the burden of blindness by sex we conducted a meta-analysis of published, population-based surveys of blindness. METHOD: Published reports were collected using a predetermined search protocol involving commercial electronic databases, hand-searching of references and direct contact with researchers. Studies were included that were population-based, included clinical examination and had a minimum sample size of 1000. The studies were critically appraised to determine methodological rigour. Data were analysed using the Cochrane Collaboration Review Manager. RESULTS: The overall odds ratio (age-adjusted) of blind women to men is 1.43 (95% CI 1.33-1.53), ranging from 1.39 (95% CI 1.20-1.61) in Africa, 1.41 (95% CI 1.29-1.54) in Asia, and 1.63 (95% CI 1.30-2.05) in industrialised countries. There was good homogeneity of findings from Africa, Asia, and the industrialised countries. Globally, women bear excess blindness compared to men. In these surveys, overall, women account for 64.5% of all blind people. The excess of blindness in women was marked among the elderly and not due only to differential life expectancy. CONCLUSION: The excess burden of blindness among women is likely due to a number of factors, which are different in industrialised countries compared to developing countries. Particular attention to gender differences in blindness is needed in the creation of targets for blindness reduction and in the development of interventions.

Adolescent↗
PubMed2000

Do clinical practice guidelines reflect research evidence?

OBJECTIVES: To examine whether existing clinical practice guidelines (CPGs) for cholesterol testing reflect research evidence and hence may control or reduce costs while maintaining or improving the quality of care. METHODS: A systematic search for published and unpublished cholesterol testing CPGs and independent critical appraisal of the CPGs by two researchers using a standard checklist. RESULTS: In four of the five CPGs analysed, the link between the research evidence and the recommendations was not maintained. The appraisal, local experience and the literature all suggest that panel composition is an important explanation, in that the greater the involvement of clinical experts in the development process of the CPGs, the less the recommendations reflected the research evidence. Even though their participation is important for CPG uptake, clinical expert panels appear to have difficulty limiting CPGs to research-based recommendations. CONCLUSIONS: Existing cholesterol testing CPGs are unlikely to improve the quality of care while controlling or reducing costs. The problem lies not with guideline implementation but with the guidelines themselves. It is unclear how best to ensure that recommendations reflect research evidence but this is likely to require significant and progressive changes to the current guideline development process, including a redefinition of the clinical experts' role.

Adult↗
PubMed1999

A systematic review of craniosacral therapy: biological plausibility, assessment reliability and clinical effectiveness.

OBJECTIVES: The objective of this research was to review critically the scientific basis of craniosacral therapy as a therapeutic intervention. DESIGN: A systematic search for and critical appraisal of research on craniosacral therapy was conducted. Medline, Embase, Healthstar, Mantis, Allied and Alternative Medicine, Scisearch and Biosis were searched from their start date to February 1999. MAIN OUTCOME MEASURES: A three-dimensional evaluative framework with related appraisal criteria: (A) craniosacral interventions and health outcomes; (B) validity of craniosacral assessment; and (C) pathophysiology of the craniosacral system. RESULTS: The available research on craniosacral treatment effectiveness constitutes low-grade evidence conducted using inadequate research protocols. One study reported negative side effects in outpatients with traumatic brain injury. Low inter-rater reliability ratings were found. CONCLUSIONS: This systematic review and critical appraisal found insufficient evidence to support craniosacral therapy. Research methods that could conclusively evaluate effectiveness have not been applied to date.

Adult↗
PubMed1999

Bone mineral density testing in social context.

Bone mineral density (BMD) testing of healthy women continues to increase, despite widespread discrediting of this test as a valid means to predict fracture risk. To find an explanation for this expanding utilization, we turn to the literature of sociology and political science. Two interdisciplinary approaches proved particularly useful in critical examination of technologies related to women and aging: feminist analysis and cross-cultural analysis. BMD testing has grown because it is marketed in ways that draw upon and perpetuate two trends in western popular culture: a) the medical model of the aging female body; and b) the fear of aging, with its associated disability, dependency, and immobility. The feedback loop between popular and scientific knowledge has created and perpetuated the notion that the aging female body is a diseased body. The trend toward defining osteoporosis entirely on the basis of BMD diagnostic criteria has resulted in the transformation of a risk factor into a disease entity. As the onus for managing risk falls increasingly on women as individuals, and as they strive to reach the preferred ideal of normality, the area that defines normality on the continuum is shrinking, while that defining abnormality is increasing. The power relations and private interests served by this altered continuum remain largely unexamined. The effect, however, is to encourage the demand for screening and diagnostic technologies, giving rise to the rapid diffusion of such technologies, even where the research evidence does not support their use.

Absorptiometry, Photon↗
PubMed1997

Anticoagulation in chronic nonvalvular atrial fibrillation: a critical appraisal and meta-analysis.

OBJECTIVE: To assess the outcomes associated with warfarin treatment of patients with chronic nonvalvular atrial fibrillation (CNVAF) for prevention of primary stroke. DATA SOURCES: MEDLINE was searched for literature published from 1987 to August 1996. Search terms used were 'atrial fibrillation' and 'anticoagulants'. STUDY SELECTION: Five published randomized controlled trials concerning primary stroke prevention. DATA EXTRACTION: Data were pooled across trials to estimate the magnitude of the effect for each of nine reported end-points. The annual probability of occurrence of each outcome was calculated, including standard errors and Mantel-Haenszel significance tests with 95% CIs. DATA SYNTHESIS: In view of the lack of blinded assessment and documented low inter-rater reliability of soft neurological end-points, the analysis was limited to the relatively objective end-points of major strokes, fatal strokes, major bleeding and fatal bleeding. Warfarin did not reduce the incidence of fatal strokes to a statistically significant extent, nor was incidence of fatal bleeding increased significantly. Warfarin reduced the absolute annual incidence of major strokes in patients with CNVAF by 0.89%, while at the same time it increased the absolute annual risk of major bleeding incidents by 1.8%. Though small, these differences were statistically significant. CONCLUSIONS: On balance, the margin between expected benefit and harm for warfarin prophylaxis in patients with CNVAF is uncomfortably thin. These results and conclusions differ from those of a previously published meta-analysis of these same studies.

Anticoagulants↗
PubMed1996

Anthropology, clinical pathology and the electronic fetal monitor: lessons from the heart.

Clinical pathology, the social process of applying disease categories and managing disease processes, is defined and its anthropological study described using examples from a study of Electronic Fetal Monitor (EFM) use during hospital obstetrical care in a rural Canadian village. Anthropological work on clinical pathology is shown to have helped doctors and nurses in this village to better understand both the cultural contingencies of their basic science knowledge and the historical contingencies of its application to the care of women during pregnancy and birth. It is argued that cultural anthropologists should study diagnostic and treatment activities, especially those involving sophisticated technology; their methods and theories make them ideally suited to this task.

Anthropology, Cultural↗
PubMed1994

Recommendations from the BC Office of Health Technology Assessment.

The BCOHTA does not make recommendations or set policy; rather, we report on the evidence. Our message is clear: For asymptomatic men, there is no evidence that annual or semi-annual PSA testing will do any good. There is substantial evidence that PSA testing will lead to considerable harm.

British Columbia↗
PubMed1990

Acceleration of linear growth following intestinal resection for Crohn disease.

Twelve patients with Crohn disease aged from 11.3 to 17.1 years, underwent intestinal resection. Eight were prepubertal or in early puberty and 4 in mid or late puberty. Pre-operative assessment included acceleration and compression barium studies and total colonoscopy. In six patients the surgical indication was failure of medical management and in six intestinal obstruction. All but one were in remission 12 months after surgery. Height velocities in the eight pre and early pubertal patients increased dramatically during 6- and 12-month post operative measurement periods compared with preoperative growth. Height velocities in the mid and late pubertal patients showed much less increase. In selected patients, surgical treatment can induce remission resulting in catch-up growth and sustained growth acceleration. In prepubertal and early pubertal patients surgery is likely to improve final adult height.

Adolescent↗
PubMed1985

Sulfated glycosaminoglycan deposition and processing at the basal epithelial surface in branching and beta-D-xyloside-inhibited embryonic salivary glands.

We investigated whether the inhibition of proteoglycan synthesis and salivary branching morphogenesis by beta-D-xyloside was related to the deposition and processing of newly synthesized glycosaminoglycans at the basal epithelial surface that correlates with normal branching activity. Forty eight-hour cultures of control and 0.5 mM beta-xyloside-treated submandibular rudiments were labeled for 2 hr with [35S]sulfate and fixed and processed for autoradiography, immediately or after 2, 4, 6, or 8 hr of postlabeling chase in nonradioactive medium. The data demonstrated that deposition of chondroitin sulfate-rich material at the basal epithelial surface was strikingly reduced in beta-xyloside-treated rudiments, while patterns of label loss during postlabeling chase were not altered.

Animals↗