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P Mitchell

Publications and source records attributed to P Mitchell.

At least 37 records · Page 2Linked to original sources
PubMed2005

Five-year incidence and progression of vascular retinopathy in persons without diabetes: the Blue Mountains Eye Study.

PURPOSE: To assess the 5-year incidence of vascular retinopathy and its associations in an older nondiabetic population. METHODS: The Blue Mountains Eye Study examined 3654 residents aged 49+ years (82.4% response rate) during 1992-1994, and re-examined 2335 (75.1% of survivors) during 1997-1999. Retinopathy lesions (microaneurysms, haemorrhages, hard or soft exudates) were assessed from 6-field retinal photographs in persons without diabetes. Incident retinopathy was assessed in those at risk. Hypertensive status was defined following the WHO/International Society of Hypertension guidelines. RESULTS: Of the 2335 re-examined, 195 had retinopathy lesions at baseline and 1725 were at risk of retinopathy after excluding subjects with diabetes (n=261), retinal vein occlusion (n=52) or missing/un-gradable photographs (n=102). The cumulative 5-year incidence was 9.7% (95% confidence intervals (CI) 8.3-11.1%). Age was the only factor significantly associated with incident retinopathy (Pfor trend=0.012). Neither fasting blood glucose (age-sex-adjusted P=0.147) nor hypertension (adjusted Pfor trend=0.43) was associated with incident retinopathy. Of the 195 with retinopathy lesions at baseline, 3.5% developed diabetes, 13.3% progressed, and 72.3% regressed/disappeared over 5 years. Progression was positively associated with elevated blood pressure (BP) (adjusted odds ratio (OR) 1.3, 95% CI 1.1-1.6 per 10 mmHg systolic BP) and inversely associated with fasting glucose level (OR 0.36, CI 0.14-0.92 per mmol/l increase). Aspirin use was weakly associated with regression (OR 2.4, CI 1.0-6.0). CONCLUSIONS: Over 5 years, retinopathy developed in 10% of older people without diabetes, while 72% of baseline lesions regressed. Age was significantly associated with the development of these lesions.

Age Distribution↗
PubMed2005

Regional differences in outcome from subarachnoid haemorrhage.

BACKGROUND: Surgeons are increasingly placed under pressure to accept publication of their results and to abide by recommendations to change practice which others derive. Considerable concern exists about misinterpretation of such data. The issue is well illustrated by this study. METHOD: Data on outcome following treatment for subarachnoid haemorrhage were prospectively collected from 1993-1998 in two centres in the British Isles: Newcastle and Nottingham. FINDINGS: Initial examination of this data suggest a substantial difference in the performance favouring Nottingham over Newcastle. The odds of a poor outcome was 1:1.86 in Newcastle compared with 1:4.26 in Nottingham giving an odds ratio of 2.3 in favour of Nottingham and this difference was highly significant with p<0.00001. On a more detailed examination taking account of confounding variables, this difference disappeared entirely. Newcastle was able to operate a less selective admissions policy than Nottingham because of the deficiency of beds at the latter unit. A summary of these results has been published elsewhere. INTERPRETATION: These results illustrate the dangers of applying statistical tools developed for simpler situations such as industrial process control to complex medical problems. We conclude that comprehensive and accurate data on all factors likely to influence the outcome for a particular treatment should be collected as an absolute prerequisite to any judgments being made on apparent statistical differences between the performances of differing units.

Adult↗
PubMed2005

Effect of awake Carotid Endarterectomy under local anaesthesia on peri-operative blood pressure: blood pressure is normalised when carotid stenosis is treated under local anaesthesia.

BACKGROUND: Carotid Endarterectomy can be performed under local, regional or general anaesthesia. One of the most important effects of the type of anaesthetic used is on the systemic blood pressure. Although variations in blood pressure during and following carotid endarterectomy have been studied previously, the effects of awake carotid endarterectomy under local anaesthesia on blood pressure and its comparison with similar procedures under similar types of anaesthesia have not. METHODS: Peri-operative blood pressure measurements were collected from the records of 25 consecutive patients for each of the following five procedures; Carotid Endarterectomy under general anaesthesia (CEAGA), Anterior Cervical Discectomy and Fusion under general anaesthesia (ACDF), Cerebral Angiography under local anaesthesia (ANG), Carotid Endarterectomy patients under local anaesthesia who were symptomatic (CEALAS) and Carotid Endarterectomy patients under local anaesthesia who were asymptomatic (CEALAA). The recordings were then analysed to find out if there were any clinically significant variations in peri-operative blood pressure. FINDINGS: There is a significant and consistent difference when the pre-operative value was compared with the 4 hour and 24 hour post-operative recordings between the local and general anaesthetic groups for carotid endarterectomy. Carotid endarterectomy reduces the systolic and diastolic blood pressures post-operatively when performed under local anaesthesia and only the diastolic pressure was reduced when performed under general anaesthesia. CONCLUSION: The study provides evidence about the effect of carotid endarterectomy on the systemic blood pressure and its variations when performed under different types of anaesthesia. There is significant post-operative reduction in both the systolic and diastolic blood pressure values and the intraoperative fluctuation is minimal when local anaesthesia is used. Further studies are required to find out how this affects the long-term blood pressure and clinical outcome of the patient.

Anesthesia, General↗
PubMed2005

Australian experience of a modified schedule of FOLFOX with high activity and tolerability and improved convenience in untreated metastatic colorectal cancer patients.

This study determined the efficacy and safety of a modified FOLFOX regimen that improved patient convenience without compromising oxaliplatin dose intensity. A total of 62 patients with previously untreated metastatic colorectal cancer were enrolled to receive, entirely as outpatients, 2-weekly cycles of oxaliplatin 100 mg m(-2) i.v. over 2 h, together with leucovorin 400 mg m(-2) over 2 h, 5-fluorouracil (5-FU) 400 mg m(-2), bolus, followed by a 46-h infusion of 5-FU at 2.4 g m(-2). Treatment was given until progression or unmanageable toxicity. In all, 61 patients received > or =one oxaliplatin dose and a median of 11 treatment cycles (range 1-20 cycles); 22 (36%) reported grade 3/4 neutropenia and 13 patients (21%) experienced grade 3 neurotoxicity; 16 patients (26%) discontinued treatment due to disease progression or death, 15 (25%) due to neurotoxicity and six (10%) due to haematological toxicity. Of the 56 eligible patients, complete or partial responses were observed in 29 or 52% (95% confidence interval 38-65%). Median progression-free survival was 8.2 months (7.1-9.9) and median overall survival was 18.7 months (14.0-23.4). In our experience, a modified schedule of FOLFOX improves convenience without compromising efficacy or toxicity.

Adult↗
PubMed2005

Oxaliplatin combined with infusional 5-fluorouracil and concomitant radiotherapy in inoperable and metastatic rectal cancer: a phase I trial.

The aim of this study was to define the recommended dose of oxaliplatin when combined with infusional 5-fluorouracil (5-FU) and concurrent pelvic radiotherapy. Eligible patients had inoperable rectal cancer, or symptomatic primary rectal cancer with metastasis. Oxaliplatin was given on day 1 of weeks 1, 3 and 5 of radiotherapy. Dose level 1 was oxaliplatin 70 mg m(-2) with 5-FU 200 mg m(-2) day(-1) continuous infusion 96 h week(-1). On dose level 2, the oxaliplatin dose was increased to 85 mg m(-2). On dose level 3, the duration of the 5-FU was increased to 168 h per week. Pelvic radiotherapy was 45 Gray (Gy) in 25 fractions over 5 weeks with a boost of 5.4 Gy. Fluorine-18 fluoro deoxyglucose and Fluorine-18 fluoro misonidazole positron emission tomography (FDG-PET and FMISO-PET) were used to assess metabolic tumour response and hypoxia. In all, 16 patients were accrued. Dose-limiting toxicities occurred in one patient at level 2 (grade 3 chest infection), and two patients at level 3 (grade 3 diarrhoea). Dose level 2 was declared the recommended dose level. FDG-PET imaging showed metabolic responses in 11 of the 12 primary tumours assessed. Four of six tumours had detectable hypoxia on FMISO-PET scans. The addition of oxaliplatin to infusional 5-FU chemoradiotherapy was feasible and generally well tolerated. For future trials, oxaliplatin 85 mg m(-2) and 5-FU 200 mg m(-2) day(-1) continuous infusion 96 h week(-1) is the recommended dose when combined with 50.4 Gy of pelvic radiotherapy.

Adult↗
PubMed2005

Predicting the risk of rupture of intracranial aneurysms based on anatomical location.

The location of intracranial aneurysms may be a significant independent risk factor for predicting aneurysm rupture. A recent report found high bleed rates from posterior communicating artery aneurysms which had not previously been noted. On this distinction hangs the decision whether to treat a large number of unruptured aneurysms. In the recent publication by the International Study of Unruptured Intracranial Aneurysms (ISUIA), two bleeds from small incidental posterior communicating artery aneurysms were noted and these aneurysms were reported to have a similar risk to aneurysms of the posterior circulation and as a result were grouped with them. This was a post hoc analysis so the justification for this assertion is tenuous. The hypothesis that posterior communicating aneurysms are of similar risk to posterior circulation aneurysms requires further testing on other data before it can be confidently accepted. A review of the literature was undertaken to define relative risks of rupture for different anatomical locations and to test the above hypothesis. Eleven papers were found to contain sufficient data to calculate rupture rates for anatomical sub groups. Studies contained a total of 30,204 patient years of follow up. Results showed the internal carotid artery to be the commonest site for unruptured aneurysms (38%). Aneurysms located in the posterior circulation had an overall annual bleed rate of 1.8%. This compares with 0.49% for the anterior circulation. The bleed rate from aneurysms of the posterior communicating artery (0.46% per year) was similar to that of the rest of the anterior circulation. The ISUIA post hoc hypothesis fails when tested on these data and the ISUIA data should be re-analysed with posterior communicating artery aneurysms grouped with the anterior circulation where they more traditionally belong.

Carotid Artery, Internal, Dissection↗
PubMed2005

Proximal migration of a lumboperitoneal unishunt system.

Proximal migration of a lumboperitoneal (LP) shunt is a rare complication associated with unishunt systems. We report three cases with a hypothesis that raised intra-abdominal pressure may be a factor responsible for the proximal migration of a LP unishunt. A rare case of proximal migration of LP shunt into the quadrigeminal cistern is also reported.

Adult↗
PubMed2005

Dyslipidaemia and microvascular disease in the retina.

PURPOSE: There are few data on the effect of serum lipids on microvascular disease. This study assessed the relationships between serum lipid levels and microvascular disease, as seen in the retina, among participants who attended a population-based study in Australia (n=3654, aged 49+years). METHODS: Diameters of retinal arterioles and venules were measured from digitised photographs of each participant to obtain an estimate of generalised arteriolar narrowing. Focal arteriolar narrowing, arteriovenous nicking, and retinopathy lesions (microaneurysms, haemorrhages, hard/soft exudates) were graded using a standard protocol. Fasting blood tests were performed in 89% of subjects. Adjusted means were calculated using general linear models. Logistic regression models were used to determine the odds ratios for retinal microvascular signs. RESULTS: After controlling for age, sex, body mass index, smoking, and mean arterial blood pressure, elevated high-density lipoprotein cholesterol was associated with narrower retinal arterioles (Ptrend=0.002) and venules (Ptrend=0.03) and with increased odds of generalised arteriolar narrowing (odds ratio 1.6, 95% confidence interval 1.1-2.2 for the highest vs the lowest quintile of high-density lipoprotein cholesterol). Serum triglyceride had a U-shaped relationship with venular diameter (Ptrend=0.003). We found no consistent pattern of association between serum total cholesterol or low-density lipoprotein cholesterol and any retinal microvascular signs. CONCLUSIONS: These findings suggest that microvascular disease in the retina may result from processes distinct from dyslipidaemia.

Aged↗
PubMed2005

Smoking and age-related macular degeneration: a review of association.

PURPOSE: Age-related macular degeneration (AMD) is the leading cause of severe and irreversible vision loss in the Western world. As there is no effective treatment for all types of AMD, identifying modifiable risk factors is of great importance. This review evaluates the epidemiological evidence associating smoking with AMD. METHODS: Systematic review of published epidemiological studies evaluated against established criteria for evidence of a causal relationship. RESULTS: In total, 17 studies (cross-sectional studies, prospective cohort studies, and case-control studies) were included in the review. A total of 13 studies found a statistically significant association between smoking and AMD with increased risk of AMD of two- to three-fold in current-smokers compared with never-smokers. Five studies found no association between smoking and AMD. There was also evidence of dose-response, a temporal relationship and reversibility of effect. CONCLUSION: The literature review confirmed a strong association between current smoking and AMD, which fulfilled established causality criteria. Cigarette smoking is likely to have toxic effects on the retina. In spite of the strength of this evidence, there appears to be a lack of awareness about the risks of developing eye disease from smoking among both healthcare professionals and the general public.

Aged↗
PubMed2005

Temporal changes in the control of blood pressure in an older Australian population.

Trends in blood pressure prevalence and control have important public health implications. We aim to document trends in hypertension prevalence, awareness and control in the older Australian population, a group at greatest risk of blood pressure related diseases. The Blue Mountains Eye Study (BMES) is a population-based study of residents aged 49 years or older, in two postcode areas of the Blue Mountains, Australia. The first cross-section (BMES I, 1992-1994) included 3654 participants (82.4% of eligible). The second cross-section (BMES II, 1997-2000) included 3509 participants, 2335 (75.1% of BMES I survivors) and 1174 (85.2% of newly eligible residents who qualified because of age or moved into the area). Detailed history and examinations were conducted. The prevalence of hypertension increased significantly from 45.4% (95% confidence interval, CI 43.7-47.0%) to 52.2% (CI 50.6-53.9%) from 1992-1994 to 1997-2000, paralleled by an increase in the population mean body mass index (BMI) from 26.1 kg/m2 (CI 26.0-26.3 kg/m2) to 27.7 kg/m2 (CI 27.5-27.9 kg/m2). Hypertension awareness decreased significantly from 79.8 to 73.0%, while treatment and control rates decreased from 71.1 to 67.3% and 56.3 to 46.5%, respectively (P<0.0001). Our results showed that elevated BMI (P<0.0001), lack of exercise (P<0.002) and serum triglyceride >2 mmol/l (P<0.0001) were significantly associated with prevalence of hypertension. We found that the prevalence of hypertension in the older Australian population was increasing while awareness, treatment and control rates decreased. Programmes to improve community awareness of hypertension, and its association with BMI may lead to further reductions in blood pressure and the burden of cardiovascular disease.

Age Distribution↗
PubMed2005

Progressing a spectrum model for defining non-melancholic depression.

OBJECTIVE: To further develop a 'spectrum model' for non-melancholic disorders that encompasses underlying personality styles and clinical patterning. METHOD: In a sample of patients with non-melancholic depression, we studied four personality constructs influencing risk to depression, assessing associational strength and specificity between personality scores and symptom and coping response patterns. RESULTS: Analyses refined four personality dimensions (anxious worrying, irritability, social inhibition, and self-centredness) for testing the model. For all dimensions, personality style was specifically linked with a mirroring 'coping' response. Quantification of specific links allowed development of a spectrum model for the non-melancholic depressive disorders in which underpinning personality style showed some specific links with the clinical 'pattern' of symptoms and coping repertoires. CONCLUSION: The model has the capacity to assist clinical assessment, identify aetiological personality influences and allow specific treatment effects for the heterogeneous non-melancholic depressive disorders to be determined.

Adaptation, Psychological↗
PubMed2005

Risk-benefit analysis of the treatment of unruptured intracranial aneurysms.

OBJECTIVES: To determine under what circumstances repair of unruptured intracranial aneurysms may be beneficial. METHODS: A life expectancy analysis of patients with unruptured aneurysms with and without repair based on prospective data from the International Study of Unruptured Intracranial Aneurysms (ISUIA). RESULTS: Life years are lost at all ages by repairing anterior circulation aneurysms under 7 mm in diameter in patients with no history of a subarachnoid haemorrhage from another aneurysm (incidental). For all other aneurysms the number of life years saved by repair is dependent on the patient's age at the time when repair is undertaken. Between 2 and 40 years are saved by repairing aneurysms in patients aged 20 years. These benefits fall to 0 when remaining life expectancy falls below 15-35 years, corresponding to the age range of 45-70 years. CONCLUSIONS: Repair of unruptured aneurysms benefits patients harbouring them by improving life expectancy except in certain circumstances. The exceptions are patients with remaining life expectancy less than 15-35 years or aged 45-70 (depending on aneurysm size and location) and patients with aneurysms of the anterior circulation under 7 mm in diameter with no history of a previous subarachnoid haemorrhage. These results are based on the findings of the ISUIA and are dependent on their accuracy.

Adolescent↗
PubMed2004

Laparoscopic appendectomy for complicated appendicitis: an evaluation of postoperative factors.

BACKGROUND: The use of laparoscopic appendectomy for complicated appendicitis is controversial. Outcomes were compared between patients who had complicated appendicitis and those who had uncomplicated appendicitis. METHODS: Consecutive patients (n = 304) who underwent laparoscopic appendectomy were studied. Patients undergoing open appendectomies also were compared ad hoc. Analgesia use, length of hospital stay, return to activity, and complication rates for the complicated and uncomplicated appendicitis subgroups were analyzed. RESULTS: Complete data were available for 243 patients (80%). There were no statistical differences in characteristics between the two groups. The operating times, lengths of hospital stay, return to activity times, complication rates, and analgesia requirements, both in the hospital and after discharge, were equivalent. A greater number of complicated cases required open conversion. Considering those with complicated appendicitis, the open group had a significantly longer mean hospital stay and a higher complication rate than those treated with laparoscopic appendectomy. CONCLUSIONS: The minimally invasive laparoscopic technique is safe and efficacious. It should be the initial procedure of choice for most cases of complicated appendicitis.

Abdominal Abscess↗
PubMed2004

Decompressive craniectomy with lattice duraplasty.

A method of opening dura for decompressive craniectomies is described. Numerous cuts intersecting in a lattice pattern allow the dura to expand in a gradual and controlled manner minimising the chances of cortical laceration or venous kinking on the craniectomy edge.

Adult↗
PubMed2004

Anaesthesia for endovascular treatment of cerebral aneurysms.

Endovascular treatment of cerebral aneuryms is now widely used and has important implications for the neuroanaesthetist. Significant issues include the decision to use general anaesthesia, factors associated with anaesthesia in the interventional radiology suite and treatment of complications. As endovascular treatment is now supported by evidence and established in practice, neuroanaesthetists should be involved in planning these procedures from a process, and individual patient, perspective.

Anesthesia↗
PubMed2004

Serial MRI in multiple sclerosis: a prospective pilot study of lesion load, whole brain volume and thalamic atrophy.

Using serial magnetic resonance imaging (MRI), we investigated the relationship between diffuse cerebral atrophy, T1 and T2 lesion volumes, mean thalamic volumes and clinical progression in patients with established multiple sclerosis (MS). Eleven patients were included in this prospective serial study. Cerebral volumes, T1 hypointense lesion volumes, and T2 hyperintense lesion volumes at baseline and at up to 3 years follow-up were assessed on MRI brain scans. As a putative measure of cerebral atrophy mean thalamic volumes were also obtained. The outcome measures were the MRI parameters and disability on Kurtzke's expanded disability status scale (EDSS). Of the 11 patients 6 worsened clinically as measured by an increase of 0.5 or more on the EDSS. Cerebral atrophy occurred in 91% of patients and was independent of changes in lesion volumes and was not associated with disease progression as determined by the EDSS.

Adult↗
PubMed2004

Five-year change in visual acuity following cataract surgery in an older community: the Blue Mountains Eye Study.

AIMS: To assess the change in visual acuity following cataract surgery in the Blue Mountains Eye Study (BMES) population. Change in visual acuity was assessed by age, sex, baseline cataract type, and baseline visual acuity. METHODS: A 5-year prospective follow-up of the population-based BMES cohort, who were initially examined in 1992. After 5 years, 2335 survivors of 3654 (75.1%) baseline BMES participants were re-examined. Slit-lamp and retro-illumination lens photographs were graded for the presence of incident cataract and evidence of cataract surgery. Visual acuity was measured using a logMAR chart, read at 2.4 m. The main outcome measure was change in the number of logMAR letters correctly identified by eyes that underwent cataract surgery during the 5-year follow-up period. RESULTS: In a multiple linear regression model, age (P<0.0001) and early age-related maculopathy (ARM) at baseline (P<0.0001) were found to affect adversely the postoperative visual acuity following the cataract surgery. As expected, eyes with any baseline cataract showed the greatest improvement in visual acuity after cataract surgery (right eyes: mean +/- s.e. change of 3.75 +/- 1.34 letters; left eyes: mean change +/- s.e. of 6.7 +/- 0.99 letters). There was also a statistically significant improvement in vision after cataract surgery in eyes with no significant lens opacity graded as present at baseline (right eyes: mean +/- s.e. change of 3.78 +/- 1.85 letters; left eyes: mean change +/- s.e. of 2.68 +/- 1.33 letters). CONCLUSIONS: Age and baseline cataract or ARM status, and baseline visual acuity were determinants of the postoperative visual outcome in older persons who underwent cataract surgery in this community.

Age Factors↗