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Biomedical subjects

P Mitchell

Publications and source records attributed to P Mitchell.

At least 73 records · Page 4Linked to original sources
PubMed2003

Unilateral visual impairment and health related quality of life: the Blue Mountains Eye Study.

BACKGROUND: There has been considerable recent interest in the impact of unilateral visual impairment on functional status and wellbeing, particularly in relation to second eye cataract surgery. AIM: To determine if unilateral visual impairment has a measurable impact on health related quality of life (HRQOL) in an older community, as assessed by the generic, multidimensional 36 item short form health survey (SF-36). METHODS: All participants of the second cross sectional Blue Mountains Eye Study (n = 3508) were invited to attend comprehensive eye examinations and complete an SF-36 questionnaire. Unilateral visual impairment was defined as visual acuity (VA) <6/12 in the worse eye and > or =6/12 in the better eye. Mild visual impairment was defined as VA <6/12 but > or =6/24, moderate as VA <6/24 but > or =6/60, and severe (blindness) as VA <6/60 in the worse eye. Cases with amblyopia (n = 48) were excluded. RESULTS: Complete data were available for 3108 participants; 227 (7.3%) had unilateral visual impairment (148 mild, 29 moderate, 50 severe). Moderate to severe non-correctable unilateral impairment was associated with poorer SF-36 profiles. After adjusting for age and sex, this group had significantly poorer scores than the unimpaired group in three of eight domains (p<0.05); limitations as a result of physical problems, social function, limitations because of emotional problems, and in the mental component score. Mental domains were more affected than physical domains. Unilateral impairment from undercorrected refraction did not measurably affect HRQOL. CONCLUSIONS: Moderate to severe non-correctable unilateral visual impairment caused by eye diseases such as cataract had a measurable impact on HRQOL.

Age Distribution↗
PubMed2002

A multicentre phase II study of cisplatin and gemcitabine for malignant mesothelioma.

Our previous phase II study of cisplatin and gemcitabine in malignant mesothelioma showed a 47.6% (95% CI 26.2-69.0%) response rate with symptom improvement in responding patients. Here we confirm these findings in a multicentre setting, and assess the effect of this treatment on quality of life and pulmonary function. Fifty-three patients with pleural malignant mesothelioma received cisplatin 100 mg m(-2) i.v. day 1 and gemcitabine 1000 mg m(-2) i.v. days 1, 8, and 15 of a 28 day cycle for a maximum of six cycles. Quality of life and pulmonary function were assessed at each cycle. The best response achieved in 52 assessable patients was: partial response, 17 (33%, 95% CI 20-46%); stable disease, 31 (60%); and progressive disease, four (8%). The median time to disease progression was 6.4 months, median survival from start of treatment 11.2 months, and median survival from diagnosis 17.3 months. Vital capacity and global quality of life remained stable in all patients and improved significantly in responding patients. Major toxicities were haematological, limiting the mean relative dose intensity of gemcitabine to 75%. This schedule of cisplatin and gemcitabine is active in malignant mesothelioma in a multicentre setting. Investigation of alternative scheduling is needed to decrease haematological toxicity and increase the relative dose intensity of gemcitabine whilst maintaining response rate and quality of life.

Aged↗
PubMed2002

Risk factors for fractures of the wrist, shoulder and ankle: the Blue Mountains Eye Study.

Few studies have examined risk factors for fractures of the wrist, shoulder or ankle. The Blue Mountains Eye Study is a population-based longitudinal study in 3654 people aged 49 years or older resident in an area west of Sydney, Australia. Detailed eye examinations and interviews were carried out at baseline (1992-3) and after 5 years (1997-9). Information about fractures sustained during follow-up were collected by a combination of self-report and a search of hospital radiology records. After 4.7 years follow-up subjects had sustained 53 fractures of the distal forearm, 20 fractures of the proximal humerus and 33 ankle fractures. In multivariate models factors independently associated with wrist fractures in women were no vigorous exercise in the past 2 weeks (relative risk RR 0.4, 95% CI 0.2-0.9) and ever use of HRT (RR 0.4, 95% CI 0.1-1.0). Factors independently associated with ankle fractures were male sex (RR 0.3, 95% CI 0.1-0.8) and visual field loss (RR 2.8, 95% CI 1.2-6.6). These findings are in keeping with other studies, and suggest that different types of osteoporotic fracture have different, if overlapping, sets of risk factors.

Aged↗
PubMed2002

Gender differences in depression risk and coping factors in a clinical sample.

OBJECTIVE: To examine gender differences in depression risk and coping factors in a clinical sample of patients with a diagnosis of DSM-IV major depression. METHOD: Patients were assessed for substance use and abuse, family history of psychiatric disorder, interpersonal depressogenic factors and lifetime history of anxiety disorders. Trait anxiety, coping styles when depressed, parental bonding, marital features and personality style were also measured. Patients were reassessed at 12-month follow-up. RESULTS: There were few gender differences in experience of depression (either in duration, type or severity prior to treatment) in a group with established episodes of major depression but women reported more emotional arousability when depressed. Women reported higher rates of dysfunctional parenting and childhood sexual abuse, and rated their partners as less caring and as more likely to be a depressogenic stressor. Men were more likely to have a generalized anxiety disorder at assessment, to use recreational drugs prior to presentation. Men were rated as having a more rigid personality style and 'Cluster A' personality traits both at assessment and follow-up. CONCLUSION: There were few gender differences in severity or course of established episodes of major depression. Gender differences were related to levels of arousal, anxiety disorders, and repertoires for dealing with depression, rather than depressive symptoms per se.

Adaptation, Psychological↗
PubMed2002

The potential of virtual reality in social skills training for people with autistic spectrum disorders.

BACKGROUND: People with autism experience profound and pervasive difficulties in the social domain. Attempts to teach social behaviours tend to adopt either a behavioural or a 'theory of mind' (ToM) approach. The beneficial aspects and limitations of both paradigms are summarized before an examination of how virtual reality technology may offer a way to combine the strengths from both approaches. METHODS: This is not an exhaustive review of the literature; rather, the papers are chosen as representative of the current understanding within each broad topic. Web of Science ISI, EMBASE and PsycInfo were searched for relevant articles. RESULTS: Behavioural and ToM approaches to social skills training achieve some success in improving specific skills or understanding. However, the failure to generalize learned behaviours to novel environments, and the unwieldy nature of some behavioural methodologies, means that there is a need for a training package that is easy to administer and successful in promoting learning across contexts. CONCLUSIONS: Virtual reality technology may be an ideal tool for allowing participants to practise behaviours in role-play situations, whilst also providing a safe environment for rule learning and repetition of tasks. Role-play within virtual environments could promote the mental simulation of social events, potentially allowing a greater insight into minds. Practice of behaviours, both within and across contexts, could also encourage a more flexible approach to social problem solving. Virtual environments offer a new and exciting perspective on social skills training for people with autistic spectrum disorders.

Autistic Disorder↗
PubMed2002

A stereoscope for image-guided surgery.

A method of image guidance for neurosurgery using the surgeon's binocular depth perception is described. Magnetic resonance volume acquisitions and surface rendering software were used to produce stereoscopic pairs of images of the surface of the heads of patients with brain tumours. Stereoscopic pairs of the surface rendering of the tumour were also produced. The two pairs of images were colour-coded and combined into one pair of 35-mm slides. A stereoscopic viewer was constructed to allow simultaneous viewing of the pair of slides and the patient's head. Registration was achieved by moving the stereoscope in space until the virtual images of the rendered surface of the head coincided with the real head. The stereoscope was then locked in position and the virtual image of the tumour was projected 'into' the patient's head to allow the surgeon to locate the tumour. The instrument was used in six cases. A lateral accuracy of 10-15 mm was achieved and a depth accuracy of 5-10 mm.

Brain Neoplasms↗
PubMed2002

Factors associated with undercorrected refractive errors in an older population: the Blue Mountains Eye Study.

AIMS: To identify characteristics of people with clinically relevant undercorrected refractive errors. METHODS: The Blue Mountains Eye Study was a population based survey of 3654 Australians aged 49-97 years. Examinations included a standardised refraction and measurement of presenting and best corrected visual acuity. Clinically relevant undercorrected refractive error was defined as improvement of >/=10 letters (2+ lines on the logMAR chart) in subjects with presenting acuity 6/9 or worse. Associations with a range of demographic and ocular variables were explored, adjusting for age and sex, presented as odds ratios (OR) with 95% confidence intervals (CI). RESULTS: Undercorrected refractive error was present in 814/3654 subjects (10.2%). Older age (p <0.001), hyperopia (OR 1.45, CI 1.15 to 1.83), longer interval from last eye examination (p <0.001), past occupation as tradesperson (OR 1.64, 1.13 to 3.29) or labourer (OR 2.00, CI 1.39 to 2.89), receipt of government pension (OR 1.47, CI 1.12 to 1.94), and living alone (OR 1.34, CI 1.05 to 1.72) were all associated with undercorrected refractive error. Past or current use of distance glasses (OR 0.25, CI 0.20 to 0.32) and driving (OR 0.67, CI 0.52 to 0.86) were associated with a lower prevalence. CONCLUSIONS: Increasing age and measures of socioeconomic disadvantage and isolation were found to predict undercorrected refractive error. Given the documented impacts from correctable visual impairment, these findings suggest a need to target education and eye care services.

Age Factors↗
PubMed2002

Failure testing cerebral arteries: are branch points weaker than unbranched vessels?

The bursting pressure of samples of cerebral arteries was measured. Eighty-five samples of cerebral arteries were taken from 11 fresh cadavers. These samples were filled with saline under pressure to the point of bursting. The bursting pressures were recorded. The mean bursting pressure of all samples was 1.8 bar (1370 mmHg). The range was 0.7-4.6 (530-3190 mmHg). The mean bursting pressures of samples containing branch points was 1.6 and that of those without branch points was 2.2. This difference was significant with p < 0.001. Samples taken from persons dying from subarachnoid haemorrhage were weaker (mean 1.45 bar) than those taken from persons dying from other causes (mean 1.971 bar). This difference was significant with p < 0.001. Bursting pressure was found to decline at 2% per year of age. This figure was different from 0 with p = 0.003.

Aged↗
PubMed2001

Effects of a 2- to 4-week course of repetitive transcranial magnetic stimulation (rTMS) on neuropsychologic functioning, electroencephalogram, and auditory threshold in depressed patients.

BACKGROUND: The safety of repetitive transcranial magnetic stimulation (rTMS) has only previously been formally studied in volunteers receiving a single session of stimulation or in a small number of depressed subjects receiving a 2-week treatment course. This study examined safety issues in depressed subjects receiving up to 4 weeks of rTMS. Efficacy results from this study have been previously reported. METHODS: Eighteen subjects with DSM-IV major depression participated in a 2-week, parallel, double-blind, sham-controlled study of rTMS treatment. Twelve subjects then went on to receive 4 weeks active rTMS in an open follow-up. We examined the effects of rTMS on neuropsychologic function (up to 4 weeks), auditory threshold (up to 6 weeks exposure to rTMS noise), and an electroencephalogram (after 2 weeks). Data were analyzed by repeated measures analysis. RESULTS: There were trends for improvement in neuropsychologic performance, probably due to practice effects. No mean changes in auditory threshold occurred, but two patients showed mild high-frequency hearing loss after several weeks of rTMS. Electroencephalograms in two patients, one of whom had sham stimulation, showed minor abnormality. CONCLUSIONS: No significant mean deficits were demonstrated in this cohort. Overall, rTMS for up to 4 weeks is safe, but individual results suggest caution and the need for further investigation of the safety of several weeks of rTMS.

Adult↗
PubMed2001

Incidence of nursing home placement in a defined community.

OBJECTIVE: To assess cumulative incidence and non-cognitive factors predicting nursing home placement in a defined older population. DESIGN AND SETTING: Six-year follow-up of a population-based cohort living west of Sydney. PARTICIPANTS: 3654 non-institutionalised residents aged 49 years or older (82.4% of those eligible) participated in baseline examinations during 1992 to 1994. MAIN OUTCOME MEASURES: Permanent nursing home admission for long-term institutionalised aged care in New South Wales, confirmed by records of approvals by the regional Aged Care Assessment Team and subsidy payments by government. RESULTS: After excluding 384 participants who moved from the area or were lost to follow-up, 162 participants (5.0%) had been admitted to nursing homes on a permanent basis by October 1999. Of participants who died since baseline, 20% had been admitted to a nursing home before death. Of those alive, 1.6% were current nursing home residents. Six-year cumulative incidence rates for nursing home placement were 0.7%, 1.1%, 2.4%, 3.9%, 9.0%, 18.3% and 34.9% for people aged 55-59, 60-64, 65-69, 70-74, 75-79, 80-84 and 85 years or older, respectively. Non-cognitive factors at baseline predicting subsequent nursing home admission included each additional year of age (risk ratio [RR], 1.14), fair or poor compared with excellent self-rated health (RR, 2.9, 3.6), walking difficulty (RR, 3.6) and current smoking (RR, 1.9). People owning their homes had a decreased likelihood of nursing home placement (RR, 0.6). CONCLUSIONS: Incidence rates of institutional aged care doubled for each five-year interval from the age of 60 years. A range of non-cognitive factors predict nursing home placement.

Aged↗
PubMed2001

Risk factors for age-related maculopathy: the Visual Impairment Project.

OBJECTIVE: To describe the risk factors and associated population attributable risk for age-related maculopathy (ARM) and age-related macular degeneration (AMD) in Australians aged 40 years and older. METHODS: Residents were recruited from 9 randomly selected urban clusters and 4 randomly selected rural clusters in Victoria, Australia. At locally established test sites, the following information was collected: visual acuity, medical and health history, lifetime sunlight exposure, dietary intake, and fundus photographs. Age-related maculopathy and AMD were graded from the fundus photographs using an international classification and grading system. Backwards logistic regression was used to identify the independent risk factors for ARM and AMD. RESULTS: The participation rate was 83% (n = 3271) among the urban residents and 92% (n = 1473) among the rural residents. Gradable fundus photographs of either eye were available for 4345 (92%) of the 4744 participants. There were 656 cases of ARM, giving a weighted prevalence of 15.1% (95% confidence limit [CL], 13.8, 16.4); and there were 30 cases of AMD, giving a weighted prevalence of 0.69% (95% CL, 0.33, 1.03). In multiple logistic regression, the risk factors for AMD were as follows: age (odds ratio [OR], 1.23; 95% CL, 1.17, 1.29), smoked cigarettes for longer than 40 years (OR, 2.39; 95% CL, 1.02, 5.57), and ever taken angiotensin-converting enzyme inhibitors (OR, 3.26; 95% CL, 1.33, 8.01). The magnitude of all of these risk factors was slightly less for ARM, and having ever taken blood cholesterol-lowering medications was also significant (OR, 1.67; 95% CL, 1.12, 2.47; P =.001). CONCLUSION: Smoking is the only modifiable risk factor for ARM and AMD, among the many environmental and systemic factors that were assessed.

Adult↗
PubMed2001

Visual impairment, age-related cataract, and mortality.

OBJECTIVE: To explore associations between visual impairment, cataract, and mortality in older persons after adjusting for other factors associated with mortality. METHODS: A population cohort of 3654 persons aged 49 years or older (82.4% of eligible residents in the Blue Mountains region, west of Sydney, Australia), were examined at the Blue Mountains Eye Study baseline period (1992-1994) and followed up 5 years later (1997-1999). Australian National Death Index data were used to confirm persons who had died since baseline. Associations between mortality and presence of visual impairment and cataract at baseline were assessed using the Cox proportional hazards regression model, controlling for age, sex, demographic and socioeconomic status, medical history, and health risk behaviors. RESULTS: By June 30, 1999, 604 participants (16.5%) had died. The age- and sex-standardized 7-year cumulative mortality rate was 26% among persons with any visual impairment and 16% in persons without visual impairment. After adjusting for factors found significantly associated with mortality, including age, male sex, low self-rated health, low socioeconomic status, systemic medical conditions, and negative health risk behaviors, the presence at baseline of any visual impairment was independently associated with increased mortality risk (risk ratio [RR], 1.7; 95% confidence interval, 1.2-2.3). The presence of age-related cataract, either nuclear (RR, 1.5), cortical (RR, 1.3), or posterior subcapsular cataract (RR, 1.5), was also significantly associated with increased mortality risk. These associations remained statistically significant when visual impairment and each type of cataract were included simultaneously in the multivariate Cox model. CONCLUSION: Visual impairment and age-related cataract may be independent risk factors for increased mortality in older persons.

Aged↗
PubMed2001

Testing the effectiveness of an osteoporosis educational program for nursing students in Thailand.

OBJECTIVE: Osteoporosis, a health problem that is on the rise, has received considerable attention among the health care community and the public. The majority of primary prevention programs for osteoporosis have been focused on women in mid-life. A concern is that young women may not be aware of osteoporosis risk factors and therefore may not be engaging in preventive behaviors. The purpose of this study was to test the effectiveness of an osteoporosis educational program for young women. METHODS: A sample of 100 female undergraduate students who were enrolled in the first year of a nursing program in Thailand were randomly assigned to a control group or an experimental group. Participants in the experimental group participated in a 3-hour osteoporosis educational program (OEP). At entry to and exit from the study, all participants completed the Osteoporosis Knowledge Test, the Osteoporosis Health Belief Scale, and the Osteoporosis Self-Efficacy Scale. RESULTS: The experimental group had higher change scores for knowledge, health belief, and self-efficacy than the control group. The OEP increased knowledge of osteoporosis in these young women. CONCLUSION: These findings indicate the need for further health education concerning the importance of dietary calcium and exercise on osteoporosis prevention in young women.

Adult↗
PubMed2001

Use of vitamin supplements and cataract: the Blue Mountains Eye Study.

PURPOSE: To investigate relationships between use of vitamin supplements and the three principal cataract types in a population-based sample. METHODS: We studied 2873 of the 3654 participants (79%) aged 49 to 97 years attending the cross-sectional Blue Mountains Eye Study who completed a detailed food frequency questionnaire, which included type, dose, and duration of vitamin supplement use. Masked grading of nuclear, cortical, and posterior subcapsular opacities from lens photographs was performed, using the Wisconsin method. RESULTS: Use of multivitamin supplements was associated with reduced prevalence of nuclear cataract, odds ratio 0.6, 95% confidence interval 0.4 to 1.0, P =.05. For both nuclear and cortical cataract, longer duration of multivitamin use was associated with reduced cataract prevalence (nuclear cataract, trend P =.02; cortical cataract, trend P =.03). Use of thiamin supplements was associated with reduced prevalence of nuclear (odds ratio 0.6, confidence interval 0.4 to 1.0, P =.03, dose trend P =.03) and cortical cataract (odds ratio 0.7, confidence interval 0.5 to 0.9, P =.01, dose trend P =.02). Riboflavin (odds ratio 0.8, confidence interval 0.6 to 1.0, P =.05) and niacin (odds ratio 0.7, confidence interval 0.6 to 1.0, P =.04) supplements exerted a weaker protective influence on cortical cataract. Vitamin A supplements were protective against nuclear cataract (odds ratio 0.4, confidence interval 0.2 to 0.8, P =.01, dose trend P =.01). Folate (odds ratio 0.4, confidence interval 0.2 to 0.9, P =.03) appeared protective for nuclear cataract, whereas both folate (odds ratio 0.6, confidence interval 0.3 to 0.9, P =.01, dose trend P =.04) and vitamin B12 supplements (odds ratio 0.7, confidence interval 0.5 to 1.0, P =.03, dose trend P =.02) were strongly protective against cortical cataract. CONCLUSIONS: Long-term use of multivitamins, B group and vitamin A supplements was associated with reduced prevalence of either nuclear or cortical cataract. A strong protective influence on cortical cataract, from use of folate or vitamin B12 supplements, is a new finding.

Aged↗
PubMed2001

Risk factors for age-related macular degeneration: Pooled findings from three continents.

OBJECTIVE: To assess the prevalence and potential risk factors for late age-related macular degeneration (AMD) in three racially similar populations from North America, Europe, and AUSTRALIA: DESIGN: Combined analysis of population-based eye disease prevalence data. PARTICIPANTS: There were 14,752 participants with gradable photographs from the Beaver Dam Eye Study (n = 4756), Rotterdam Study (n = 6411), and Blue Mountains Eye Study (n = 3585). MAIN OUTCOME MEASURES: AMD diagnosis was made from masked grading of stereo macular photographs. Final classification of AMD cases was agreed by consensus between study investigators. RESULTS: AMD prevalence was strongly age related. Overall, AMD was present in 0.2% of the combined population aged 55 to 64 years, rising to 13% of the population older than 85 years. Prevalence of neovascular AMD (NV) increased from 0.17% among subjects aged 55 to 64 years to 5.8% for those older than 85 years. Prevalence of pure geographic atrophy (GA) increased from 0.04% to 4.2% for these age groups. There were no significant gender differences in the prevalence of NV or GA. Subjects in the Rotterdam population had a significantly lower age-adjusted and smoking-adjusted risk of NV than subjects in the Beaver Dam and Blue Mountains populations. Apart from age, tobacco smoking was the only risk factor consistently associated with any form of AMD in all sites separately and in pooled analyses over the three sites. CONCLUSIONS: These combined data from racially similar communities across three continents provide strong and consistent evidence that tobacco smoking is the principal known preventable exposure associated with any form of AMD.

Adult↗
PubMed2001

Sensitivity and specificity of tests to detect eye disease in an older population.

OBJECTIVE: To compare the ability of tests of visual function to detect the presence of eye disease. DESIGN: Cross-sectional study. PARTICIPANTS: Three thousand six hundred fifty-four of 4433 (82.4%) eligible residents of an area near Sydney aged 49 years and older had a detailed eye examination, including retinal and lens photography and subsequent grading of eye disease, tests of presenting and corrected visual acuity, contrast sensitivity, screening visual field and intraocular pressure. MAIN OUTCOME MEASURES: Receiver operator characteristic (ROC) curves were created and area under the curve compared for each vision test. Sensitivity and specificity were calculated for each test. RESULTS: No single vision test predicted the presence of eye disease with any consistency. Best-corrected visual acuity or contrast sensitivity had the highest area under the ROC curve for most eye diseases examined but had poor sensitivity and specificity. For glaucoma and diabetic retinopathy there was no difference in area under the curve for any of the tests examined, and no test had a good balance of sensitivity and specificity. Screening tests (performed with presenting correction) did not perform as well as nonscreening tests (those carried out after refraction with best correction). CONCLUSIONS: Current vision tests are not particularly good at detecting eye disease compared with the "gold standard" of a full eye examination performed by an ophthalmologist. Further work in this area should be carried out before vision screening programs can be recommended for implementation among older people.

Aged↗