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P Mitchell

Publications and source records attributed to P Mitchell.

At least 55 records · Page 3Linked to original sources
PubMed2004

Open-angle glaucoma and systemic thyroid disease in an older population: The Blue Mountains Eye Study.

PURPOSE: To assess whether thyroid disease is independently associated with open-angle glaucoma (OAG), using history of thyroid disease and current thyroxine use. METHODS: The Blue Mountains Eye Study examined 3654 persons, aged 49-97 years. Interviewers collected self-reported history of diagnosis and treatment for thyroid disease. Eye examinations included applanation tonometry, stereoscopic optic disc photography and automated perimetry. OAG was diagnosed from the presence of matching typical glaucomatous field changes and optic disc cupping, independent of intraocular pressure. Associations between thyroid disease (history and treatment) and OAG were assessed in a multivariate model. RESULTS: Of 324 participants (8.9%) reporting history of thyroid disease, 147 (4.0%) were currently using thyroxine. Although we could not accurately categorize the thyroid disorder for all cases, current use of thyroxine suggests a prior hypothyroid state. All thyroid disease subgroups affected women more frequently than men, P=0.001. OAG was diagnosed in 108 subjects (3.0%) and was more frequent in those reporting past thyroid disease (4.6 vs 2.8%). This relationship was not statistically significant after adjusting for potential confounders, multivariate odds ratio (OR) 1.6; 95% confidence interval (95% CI) 0.9-2.9. OAG was significantly more frequent, however, in subjects reporting current thyroxine use (6.8 vs 2.8%), multivariate OR 2.1; 95% CI 1.0-4.4, or history of thyroid surgery (6.5 vs 2.8%), multivariate OR 2.5; 95% CI 1.0-6.2. CONCLUSIONS: This population-based study suggests that thyroid disease, indicated by current thyroxine use or past thyroid surgery, could be independently related to OAG.

Age Distribution↗
PubMed2004

Effects of cataract type and location on visual function: the Blue Mountains Eye Study.

PURPOSE: To measure the effect of cataract type, severity and location on presenting, and best-corrected visual acuity, contrast sensitivity, and glare disability. METHODS: In all, 3654 (82.4% participation rate) eligible noninstitutionalised residents aged 49 years or older, living in two postcode areas of the Blue Mountains, Australia, received detailed eye examinations including visual acuity, contrast sensitivity, and glare disability testing. Data from right eyes were analysed using multiple regression modelling. RESULTS: The effect of age on visual acuity and contrast sensitivity only became evident in persons aged at least 60 years. Cataract severity was inversely related to visual acuity and contrast sensitivity. Late posterior subcapsular cataract caused the greatest reduction in visual acuity. Early grade cataract caused significant reduction in contrast sensitivity at intermediate and high spatial frequencies, but late grade cataract reduced contrast sensitivity across all spatial frequencies. There was insufficient study power to detect consistent significant effect of cataract on glare disability tests or cortical cataract location on visual function. CONCLUSIONS: Age at least 60 years, cataract type, and cataract severity were principal determinants of visual acuity and contrast sensitivity in this study. Axial and superotemporally located cortical cataract had the greatest effect on visual function tests.

Aged↗
PubMed2004

Studying personality characteristics in bipolar depressed subjects: how comparator group selection can dictate results.

OBJECTIVE: To examine the extent to which identification of any distinct personality characteristics in bipolar subjects are influenced by selection of the comparison diagnostic group. METHOD: Scores were compared on several general measures of personality style and, additionally, the prevalence of disordered personality functioning was examined in a sample of 198 non-psychotic depressed subjects, 39 with bipolar depression and 159 with unipolar depression. RESULTS: When the bipolar subjects were separately compared with unipolar subjects, and to sub-sets of those with clinically and DSM-IV defined melancholic and non-melancholic depression, quite differing results were suggested. In essence, clinically-defined melancholic subjects had the least personality psychopathology in comparison with the non-melancholic and bipolar subjects. CONCLUSION: Whether subjects with bipolar disorder have any distinct personality characteristics or over-represented co-morbid personality disorders remains quite unclear when reference is made to the literature. We suggest that inconsistencies across studies may reflect choice and representation of depressive sub-types within the unipolar comparator group.

Adult↗
PubMed2004

The effect of optic disc diameter on vertical cup to disc ratio percentiles in a population based cohort: the Blue Mountains Eye Study.

OBJECTIVE: The 97.5th percentile for vertical cup to disc ratio (VCDR) has been proposed as a useful tool to assist in the diagnosis of glaucoma in population studies. Previous reports of VCDR percentiles have either not been adjusted for disc size or have been calculated by regression analysis from small hospital based cohorts. The authors' aim was to generate VCDR percentiles in a large, population based sample. METHODS: Data were collected from 3654 individuals, aged 49 years or older, living in the Blue Mountains, west of Sydney. Vertical disc diameter and VCDR were determined by planimetry from stereo optic disc photographs. The distribution of VCDR and percentiles (95th, 97.5th, 99th) were calculated. RESULTS: 6678 eyes were included in the analysis. Median cup to disc ratio, 95th, 97.5th, and 99th percentile increased with vertical optic disc diameter in a linear fashion. An increase of 0.2 in median VCDR (0.35 to 0.55) was observed between small (1.1-1.3 mm) and large (1.8-2.0 mm) optic discs. An equivalent increase of 0.2 (0.59 to 0.74) was observed for the 97.5th percentile from small to large discs. CONCLUSION: VCDR percentiles for a "normal" population, adjusted for vertical optic disc diameter are presented. One quarter of all discs fell within the small or large disc categories highlighting the importance for estimating optic disc size. These data may assist in the diagnosis of glaucoma in clinical practice as well as providing a normative database. Sole use of VCDR percentile cut offs in defining glaucoma cases in population surveys requires further validation.

Fundus Oculi↗
PubMed2004

Cost utility of screening and treatment for early age related macular degeneration with zinc and antioxidants.

AIM: To assess the cost effectiveness of high dose zinc and antioxidants for delaying and reducing the progression of early age related macular degeneration (AMD). BACKGROUND: AMD is the leading cause of severe vision impairment and blindness in older people throughout the developed world. It currently affects around 420 000 people in the United Kingdom. METHODS: A cost utility analysis (CUA) was conducted to estimate the cost per quality adjusted life year (QALY) for screening a cohort of men and women, aged 55 years and over, for early AMD and then treating them with zinc and antioxidants. The incremental CUA was based on a decision analytic model, comparing screening with a no screening comparator (current practice). Extensive one way sensitivity analysis of parameters was conducted to determine the robustness of the model. RESULTS: In this model the cost effectiveness of screening for early AMD was pound 22 722 per quality adjusted life year (QALY) saved. The cost per QALY decreased to pound 18 948 if photodynamic therapy with verteporfin savings were included. CONCLUSIONS: Screening for, and prophylactic treatment of, early AMD is estimated to cost around pound 22 700 per QALY saved. This cost falls within accepted levels to warrant further investigation. These findings have implications for ophthalmic practice and healthcare planning.

Aged↗
PubMed2004

Cost utility of photodynamic therapy for predominantly classic neovascular age related macular degeneration.

BACKGROUND/AIM: Age related macular degeneration (AMD) is the leading cause of severe vision impairment and blindness in older people throughout the developed world and currently affects around 420 000 UK citizens. Choroidal neovascularisation (CNV) is treatable with photodynamic therapy (PDT) but is expensive at over pound 1200 per treatment. The aim of this study was to assess the cost utility of PDT for better eye, predominantly classic, subfoveal choroidal neovascular lesions secondary to AMD. METHODS: Cost utility analysis (CUA) was conducted to estimate the cost effectiveness of PDT for scenarios involving reasonable (6/12) and poor (6/60) visual acuity. The models incorporated data from the Treatment of Age-related Macular Degeneration with PDT (TAP) Study and patient based utilities. The incremental CUA was based on decision analytical models, comparing treatment to a placebo comparator. Extensive one way sensitivity analysis of parameters was conducted to determine the robustness of the model. A discount rate of 6% was used for costs and quality adjusted life years (QALY). RESULTS: Model 1: in people with reasonable initial visual acuity, the cost utility of treating applicable neovascular AMD lesions was pound 31 607 per QALY saved, with a sensitivity analysis range from pound 25 285 to pound 37 928. Model 2: in people with poor initial visual acuity, the cost utility was pound 63 214 per QALY saved, with a sensitivity analysis range from pound 54 183 to pound 75 856. CONCLUSIONS: PDT treatment is the only available treatment for some forms of neovascular ("wet") AMD. Under these assumptions, PDT can be considered moderately cost effective for those with reasonable visual acuity but less cost effective for those with initial poor visual acuity. These findings have implications for ophthalmic practice and healthcare planning.

Aged↗
PubMed2004

Consequences of amblyopia on education, occupation, and long term vision loss.

AIMS: To describe the effect of amblyopia on education, occupation, and 5 year incident vision loss. METHODS: 3654 participants aged 49 years or older participated in the Blue Mountains Eye Study (BMES I, 1992-4) and 2335 (75.1% of survivors) were re-examined (BMES II, 1997-9). All participants underwent detailed eye examination. Amblyopia, defined as best corrected visual acuity of less than or equal to 6/9 and not attributable directly to any underlying structural abnormality of the eye or the visual pathway, was identified in 118 participants (3.2%) in BMES I, of whom 73 were re-examined in BMES II. Occupation and educational classifications used definitions of the Australian Bureau of Statistics. RESULTS: The mean age of people with amblyopia seen at baseline was 67.0 years. Amblyopia did not affect lifetime occupational class (p = 0.5), but fewer people completed higher university degrees (p = 0.05). In people with amblyopia, there was an increased risk of 5 year incident visual impairment in the better seeing eye worse than 6/12, relative risk (RR) 2.7, 95% confidence interval (CI) 1.6 to 4.6. One of 11 (9.1%) people with amblyopia showed significant improvement in visual acuity in the poorer seeing eye after a two line (10 logMAR letter) vision loss in the better seeing eye. CONCLUSION: This study further documents the longitudinal history of amblyopia using population based data.

Aged↗
PubMed2004

Retinal vessel wall signs and the 5 year incidence of age related maculopathy: the Blue Mountains Eye Study.

AIMS: To assess whether retinal arteriolar wall changes (focal narrowing and arteriovenous nicking) are associated with an increased 5 year risk of age related maculopathy (ARM). METHODS: The Blue Mountains Eye Study examined 3654 residents aged 49+ years living in a defined area, during 1992-4 (82.4% participation). After 5 years, 2335 surviving participants (75.1%) were re-examined during 1997-9. Retinal photographs were graded using the Wisconsin ARM grading system. Incident late (neovascular or atrophic) or early stage ARM was defined using a side by side grading method. Focal arteriolar narrowing (localised constricted arteriolar segments causing a sausage-like appearance), and arteriovenous (AV) nicking (constriction on both sides of the venule where crossed by an arteriole), were graded by comparison with standard photographs. All retinal vessels passing through a circumferential zone 0.5-1.0 disc diameters from the optic disc margin were measured from digitised images. Summarised estimates for central retinal arteriolar equivalent (CRAE) represent an average diameter of arterioles for that eye. Associations were assessed after adjusting for age, sex, smoking, mean arterial blood pressure, and other vascular risk factors. RESULTS: Of 2314 baseline participants at risk of late stage ARM, either late stage lesion developed in 34 participants (1.5%). Of 2203 at risk of early stage ARM, this sign developed in 197 participants (8.9%). Focal arteriolar narrowing was present at baseline in at least one eye of 162 survivors (6.9%) and severe AV nicking was present in 187 people (8.1%). Over 5 years, 4.9% of subjects with and 1.2% of those without focal narrowing developed either late stage ARM lesion, age adjusted relative risk (RR) 2.3, 95% confidence interval (CI) 1.0 to 5.1, multivariate adjusted odds ratios (OR) 2.1 (95% CI 0.9 to 4.9). Similarly, 3.7% of subjects with and 1.3% of those without severe AV nicking developed late ARM lesions, age adjusted RR 2.1 (95% CI 0.9 to 5.1), multivariate adjusted OR 2.2 (95% CI 0.9 to 5.6). Corresponding age adjusted RR and multivariate adjusted OR for development of early stage ARM were 1.4 (95% CI 0.9 to 2.0) and 1.3 (95% CI 0.8 to 2.1) for focal arteriolar narrowing, and 1.6 (95% CI 1.0 to 2.3) and 1.8 (95% CI 1.1 to 2.9) for severe AV nicking, respectively. No associations between baseline CRAE and 5 year incident late or early stage ARM were found. CONCLUSIONS: Although of borderline statistical significance, the consistent associations found in this study suggest that structural retinal arteriolar changes may either contribute to ARM progression or may share common pathological pathways with ARM.

Aged↗
PubMed2004

Clonal strains of Pseudomonas aeruginosa in paediatric and adult cystic fibrosis units.

Despite recent reports of clonal strains of Pseudomonas aeruginosa in cystic fibrosis (CF) units, the need for routine microbiological surveillance remains contentious. Sputum was collected prospectively from productive patients attending the regional paediatric and adult CF units in Brisbane, Australia. All P. aeruginosa isolates were typed using pulsed-field gel electrophoresis. Spirometry, anthropometrics, hospitalisations and antibiotic sensitivity data were recorded. The first 100 sputum samples (first 50 patients at each clinic) harboured 163 isolates of P. aeruginosa. A total of 39 patients shared a common strain (pulsotype 2), 20 patients shared a strain with at least one other patient and 41 patients harboured unique strains. Eight patients shared a strain identical to a previously reported Australian transmissible strain (pulsotype 1). Compared with the unique strain group, patients harbouring pulsotype 2 were younger and had poorer lung function. Treatment requirements were similar in these two groups, as were the rates of multiresistance. In conclusion, 59% of patients harboured a clonal strain, supporting the need for routine microbiological surveillance. In contrast to previously described clonal strains, the dominant pulsotype was indistinguishable from nonclonal strains with respect to both colonial morphology and multiresistance. The clinical significance of clonal strains remains uncertain and requires longitudinal study.

Adolescent↗
PubMed2004

Allograft impaction and cement penetration after revision hip replacement. A histomorphometric analysis in the cadaver femur.

We studied various aspects of graft impaction and penetration of cement in an experimental model. Cancellous bone was removed proximally and local diaphyseal lytic defects were simulated in six human cadaver femora. After impaction grafting the specimens were sectioned and prepared for histomorphometric analysis. The porosity of the graft was lowest in Gruen zone 4 (52%) and highest in Gruen zone 1 (76%). At the levels of Gruen zones 6 and 2 the entire cross-section was almost filled with cement. Cement sometimes reached the endosteal surface in other Gruen zones. The mean peak impaction forces exerted with the impactors were negatively correlated with the porosity of the graft.

Arthroplasty, Replacement, Hip↗
PubMed2004

A review of 187 gunshot wound admissions to a teaching hospital over a 54-month period: training and service implications.

BACKGROUND: Violence involving the use of firearms has increased in the UK over the past decade. This study assesses the implications of such injuries for service provision and training by reviewing the experience at one hospital. METHODS: Accident and emergency triage data were searched for patients presenting with gunshot wounds over a 54-month period. Case notes were reviewed and patterns of care established. The resources required for clinical management were ascertained, and the financial consequences determined at contemporary full cost. RESULTS: There were 187 attendances with 247 wounds. Mean age was 21 years (range, 8-63 years). Of the attendances, 69% were out of normal working hours. Of the 187 cases, 97 patients were admitted to one hospital (83 of whom required surgery) and 10 patients were transferred to other hospitals (6 for plastic surgery not available at the Manchester Royal Infirmary and 4 due to lack of beds). Of the 80 patients who were not admitted, 4 died in accident and emergency, the rest were either air gun wounds or relatively simple higher calibre injuries. A wide range of surgical specialties was involved (limb injury, 53; thoraco-abdominal and vascular, 28; head and neck, 5; and orbit, 2), and combinations of injuries transgressed specialty and sub-specialty boundaries. The total cost of patient care was pound 267,000. CONCLUSIONS: Gunshot wounds present a heavy demand on the clinical and financial resources of the receiving hospital, and surgeons responsible for unselected acute admissions in "general surgery" should be capable of dealing with these indiscriminate injuries. Current training and service trends towards increasing sub-specialisation may mitigate against them achieving or retaining this capability.

Adolescent↗
PubMed2003

Pharmacokinetics and pharmacodynamics of rosuvastatin in subjects with hepatic impairment.

OBJECTIVE: To assess the effect of chronic hepatic impairment on rosuvastatin disposition, pharmacodynamic activity and tolerability. METHODS: This was an open-label, non-randomised, parallel-group trial. Six subjects were enrolled in each of three hepatic-function strata: Child-Pugh class A (CP-A, mild impairment), Child-Pugh class B (CP-B, moderate impairment) and normal hepatic function; the latter two strata were age, weight, race, sex and smoking history matched. All subjects were given rosuvastatin 10 mg for 14 days. RESULTS: In subjects with CP-A, and in four of six subjects with CP-B, rosuvastatin steady-state AUC(0-24) and C(max) were similar to subjects with normal hepatic function (geometric mean values 60.7 ng h/ml and 6.02 ng/ml, respectively). Two of six subjects with CP-B who had the highest CP scores (i.e. the highest degrees of hepatic impairment) had the highest AUC(0-24) (128 ng h/ml and 242 ng h/ml) and C(max) (23.4 ng/ml and 96.7 ng/ml) values. Low-density lipoprotein cholesterol (LDL-C) was decreased in all strata, but the response was more variable in the CP-B group. Rosuvastatin was well tolerated, and the safety profile was similar in subjects with hepatic impairment and normal hepatic function. CONCLUSION: In most subjects with mild-to-moderate hepatic impairment, the steady-state pharmacokinetics of rosuvastatin were similar to subjects with normal hepatic function (more extensive hepatic impairment may increase systemic exposure to rosuvastatin), and most had LDL-C reductions similar to subjects with normal hepatic function.

Adult↗
PubMed2003

Is Doppler ultrasound sufficient as the sole investigation before carotid endarterectomy?

BACKGROUND AND AIMS: Doppler ultrasound (DU) of the extracranial carotid arteries has been advocated as the sole imaging modality in carotid endarterectomy (CE) candidates. However this approach fails to identify patients with potentially significant intracranial disease, at high risk of stroke and death. Therefore, many stroke clinicians recommend angiography after screening DU. We aimed to identify the proportion of cases referred for CE in whom the identification of intracranial disease could have altered management. METHODS: Two neuroradiologists, blinded to the clinical history, reviewed the films of 111 CE candidates, predominantly of Caucasian background, who had undergone carotid angiography after screening DU. Intracranial stenoses >50% luminal diameter, incidental aneurysms and non-atherosclerotic lesions were documented. Demographic and epidemiological data were collected. RESULTS: Of the 111 patients, 87 had >50% extracranial stenoses although two thirds were asymptomatic. Intracranial stenotic lesions were recorded in 29% of patients. Over half of these were tandem lesions, distal to an extracranial stenosis. Aneurysms were found in 4.5% of patients. CONCLUSIONS: DU alone would have failed to detect significant intracranial disease in nearly a third of cases. These patients are at high risk of stroke. The identification of this group allows more aggressive stroke prevention therapy.

Carotid Arteries↗
PubMed2003

Gender differences in response to differing antidepressant drug classes: two negative studies.

BACKGROUND: A recent US study presented data suggesting that depressed women are more likely to respond to selective serotonin reuptake inhibitor (SSRI) than tricyclic (TCA) antidepressant drug therapies. We have undertaken replication studies in two independent databases. METHOD: We have examined for gender differences in SSRI and TCA antidepressant response in both retrospective and prospective naturalistic uncontrolled studies, and in subsets of melancholic and non-melancholic depressed subjects. As the US study had indicated that women under the age of 40 years were particularly likely to show a differential response to SSRIs, we examined for age, gender and interactional effects. In addition, we examined for differential SSRI and TCA responsiveness in a subset of patients who had received drugs from both classes. RESULTS: We failed to find evidence of women having a preferential response to SSRI medication or, conversely, of men having a superior response to TCA medication. Older age, however, was associated with a superior TCA response and younger age with a superior SSRI response. CONCLUSION: As few studies have examined for differential gender and age effects in response to narrow action and broad action antidepressant drugs across major depressive subtypes, gender differential effects remain to be established.

Adult↗
PubMed2003

An Australian validation study of the temperament and character inventory.

OBJECTIVE: To assess the validity of the temperament and character inventory (TCI) measure in an Australian sample. METHOD: A sample of depressed subjects completed the TCI and a measure assessing personality disorder constructs (PDCs), while family members and psychiatrists also returned PDC ratings. RESULTS: Factor analyses generally supported the TCI constructs, when the temperament and character scales were analysed separately. Self-reported PDC scores were validated against corroborative witness ratings and used to assess the TCIs concurrent validity. Validation analyses supported all TCI temperament scales, but the Self-transcendence Character scale was unassociated with PDC scores. The remaining two character scales (i.e. cooperativeness and self-directedness) were non-specifically associated with all PDC scores. CONCLUSION: Study results support the validity of the TCI scales, but question the best model for conceptualizing the TCI. It is suggested that two character scales quantify disordered functioning, while temperament scales quantify style, constructs that may be inter-related or independent in individual subjects.

Adult↗
PubMed2003

Female reproductive factors and open angle glaucoma: the Blue Mountains Eye Study.

AIMS: To determine whether endogenous oestrogen exposures are associated with open angle glaucoma (OAG). METHODS: The Blue Mountains Eye Study examined 2072 women aged 49-97 years during 1992-4. Questions about female reproductive factors included age at menarche and menopause, parity, and use of hormone replacement therapy. Applanation tonometry, visual field tests, and stereo-optic disc photographs were performed. OAG was diagnosed when glaucomatous visual fields matched optic disc changes. Ocular hypertension (OH) was defined in the absence of glaucoma, but with intraocular pressure >or=22 mm Hg. RESULTS: A significantly increased OAG risk with later (>13 years) compared with earlier ( or=50 years), adjusted OR = 1.7; CI: 0.7 to 3.8, and for shorter duration of endogenous oestrogen exposure (<30 years), adjusted OR = 1.8; CI: 0.6 to 5.3. Increasing parity was associated with an increased risk of OAG (p = 0.03) and decreased risk of OH (p = 0.03). CONCLUSION: The modest associations found in relation to late menarche and increased parity do not allow the exclusion of a possible role for endogenous female hormones in the pathogenesis of OAG.

Age Factors↗
PubMed2003

Five year incidence of cataract surgery: the Blue Mountains Eye Study.

AIMS: To assess the 5 year incidence of cataract surgery in an older population based prospective cohort. METHODS: 5 Year prospective follow up of the population based Blue Mountains Eye Study (BMES) performed in 1992. The follow up study examined 2335 survivors (75.1%) of the 3654 baseline participants. Baseline and 5 year slit lamp and retroillumination lens photographs were graded for presence of cortical, nuclear, or posterior subcapsular cataract using the Wisconsin cataract grading method and cataract surgery was documented from the history and the clinical examination. RESULTS: An overall cataract surgery rate of 5.7% in first or both eyes was documented. The incidence was 0.3% in people aged 49-54 years at baseline, 1.7% for ages 55-64 years, 7.9% for ages 65 to 74 years, and 17.4% in people aged 75 years or older. The rate of surgery in first or both eyes was 6.0% in women and 5.2% in men, age adjusted p = 0.66. Bilateral cataract surgery was performed during follow up on 2.7% of participants, while 43.1% of unilateral phakic cases had second eye surgery. Presence of any posterior subcapsular (PSC) cataract, either alone or in combination with other cataract types, was the most likely type of cataract at baseline to be associated with incident cataract surgery. Baseline age was the most important non-ocular variable predicting incident cataract surgery. CONCLUSIONS: This study has documented age specific rates for 5 year incident cataract surgery in an older community. The finding of relatively similar incidence rates and ocular predictors of cataract surgery to those reported by the Beaver Dam Eye Study, Wisconsin, United States, is of interest, given previous documented similarities between these two populations.

Age Distribution↗