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Biomedical subjects

M M Brown

Publications and source records attributed to M M Brown.

At least 55 records · Page 3Linked to original sources
PubMed2000

Arteriovenous adventitial sheathotomy for the treatment of macular edema associated with branch retinal vein occlusion.

PURPOSE: To report arteriovenous adventitial sheathotomy for treatment of macular edema associated with branch retinal vein occlusion. METHODS: Case reports with review. Five eyes of five patients with best-corrected visual acuity of less than 20/200 secondary to branch retinal vein occlusion had pars plana vitrectomy and arteriovenous adventitial sheathotomy and were followed postoperatively for a mean of 6.5 years (range, 5 to 7 years). RESULTS: In four of five eyes, the best-corrected visual acuity improved to 20/30 to 20/70. In the remaining eye, visual acuity remained at finger counting secondary to macular ischemia. CONCLUSION: Arteriovenous adventitial sheathotomy may be beneficial for select patients with poor vision secondary to branch retinal vein occlusion.

Aged↗
PubMed2000

Difference between ophthalmologists' and patients' perceptions of quality of life associated with age-related macular degeneration.

BACKGROUND: There may be a wide disparity between the perceptions of patients and those of their treating physicians concerning the quality of life associated with a given state of health. Because of this potential for difference of opinion, we performed a study to evaluate patients' and ophthalmologists' perceptions of quality of life, as measured by utility analysis, associated with visual loss secondary to age-related macular degeneration (AMD). METHODS: Cross-sectional study. Utilities were assessed, by means of both the time trade-off method and the standard gamble method, for various degrees of theoretical visual loss secondary to AMD for ophthalmologists-in-training and graduate ophthalmologists. These were compared to utilities for a known population of patients with actual visual loss due to AMD. A utility of 1.0 is associated with perfect health, whereas a utility of 0.0 is associated with death. RESULTS: With both the time trade-off and standard gamble methods, the patients had lower mean utilities than did the ophthalmologists for the same degrees of visual loss secondary to AMD. The ophthalmologists were significantly less willing than the patients to trade years of remaining life for perfect vision with the time tradeoff method (p < or = 0.01), and with the standard gamble method they were less willing than the patients to take the risk of dying in return for perfect vision. Given the scenario of counting fingers or worse vision in both eyes, the ophthalmologists were willing to trade 3.3 of every 10 years of remaining life for perfect vision in both eyes, whereas the patients with actual vision of counting fingers or worse in both eyes were willing to trade 6.0 of every 10 years of remaining life for this result. INTERPRETATION: When presented with the scenario of visual loss secondary to AMD, ophthalmologists substantially underestimated its effect on patients' quality of life.

Adult↗
PubMed2000

Converting visual acuity to utilities.

BACKGROUND: Utility theory can be used to quantify dysfunction associated with various diseases and thus can represent a "hard" measure of quality of life. By determining utility values, one can compare the quality of life of patients with ocular disease to that of patients with non-ophthalmic problems. We performed a study to determine whether utility values from patients with ocular disease are associated with clinical variables, including visual acuity in the better-seeing eye, and to develop a mathematical method for converting visual acuity to utility value, if there is an association between the two. METHODS: Cross-sectional study. A total of 239 patients from a tertiary care retinal practice with various ocular conditions, including macular degeneration, cataract, glaucoma and diabetic retinopathy, were interviewed under standardized conditions to determine their utility values by the time trade-off technique. Visual acuity, duration of visual loss and number of concomitant conditions were also determined. Multiple linear regression was performed to determine which variables were associated with utility values. RESULTS: The mean acuity in the better-seeing eye was 0.479 (near 20/40 vision). The mean utility value was 0.72. Accordingly, the average patient in our series was willing to trade 2.8 of every 10 remaining years of life to obtain perfect vision in both eyes. Utility value was significantly associated with visual acuity in the better-seeing eye (F = 69.1, p < 0.001). Other variables were not significantly associated with utility value. The association with duration of visual loss approached statistical significance (p = 0.075). Utility values (U) for patients with ocular disease can be derived from the following formula: U = (0.374)(visual acuity in better-seeing eye) + 0.514. INTERPRETATION: Utility values from patients with ocular disease were strongly associated with visual acuity and could be estimated mathematically.

Aged↗
PubMed2000

Incremental cost effectiveness of laser photocoagulation for subfoveal choroidal neovascularization.

OBJECTIVE: To perform a patient preference-based, incremental cost-effectiveness analysis for laser treatment of subfoveal choroidal neovascularization. DESIGN: Computer-based econometric modeling. METHODS: The cost effectiveness of laser photocoagulation therapy was compared with the natural course of subfoveal choroidal neovascularization. The model applied long-term visual data from previous clinical trials, utility analysis (which reflects patient perceptions of quality of life associated with a health state), decision analysis with Markov modeling, and the economic principles of present value analysis with discounting to account for the time value of money. DATABASE: Data from patients eligible for treatment of subfoveal choroidal neovascularization obtained by researchers in the Macular Photocoagulation Study were used for the analysis. INTERVENTION: Modeled laser therapy for subfoveal choroidal neovasacularization in patients with age-related macular degeneration. MAIN OUTCOME MEASURE: Cost per quality-adjusted life-year ($/QALY gained) associated with laser therapy. RESULTS: Laser photocoagulation therapy for subfoveal choroidal neovascularization, as compared with no treatment, resulted in a mean gain of 0.257 QALYs per treated patient. Using a yearly discount rate of 3% to account for the time value of money and inflation, the resultant $/QALY gained was $5629. Sensitivity analysis used in the cost-effectiveness analysis resulted in a $/QALY gained of $4974 with no gained discount rate and $11,633 with a yearly discount rate of 10%. CONCLUSIONS: The incremental expense of laser therapy for the treatment of subfoveal choroidal neovascularization appears to be highly cost effective. The result, which takes into account patient preference-based utility data, compares quite favorably with other interventional therapies across different medical specialties.

Aged↗
PubMed2000

Incremental cost-effectiveness of laser therapy for choroidal neovascularization associated with histoplasmosis.

PURPOSE: Laser photocoagulation has been shown in a large clinical trial to be efficacious in reducing the degree of vision loss occurring secondary to choroidal neovascularization (CNV) associated with ocular histoplasmosis. Nevertheless, data are lacking concerning the impact of the therapy on quality of life and its value to stakeholders in health care. Recently, information concerning the utility value of visual states has become available. Accordingly, the authors undertook to ascertain the cost-effectiveness of laser photocoagulation for the treatment of extrafoveal CNV occurring in eyes with ocular histoplasmosis. METHODS: Design--A computer simulation, econometric model is presented to evaluate the incremental cost-effectiveness of laser photocoagulation therapy, as compared with the natural course of the disease, for the treatment of patients with extrafoveal CNV associated with ocular histoplasmosis. The model applies long-term visual data from previous clinical trials, utility analysis (which reflects patient perceptions of quality of life), decision analysis with Markov modeling, and present value analysis with discounting to account for the time value of money. Outcome measure--Cost per quality-adjusted life-year gained from treatment. RESULTS: Laser photocoagulation therapy for extrafoveal CNV associated with ocular histoplasmosis costs $4167 1999 US dollars (at a 3% discount rate) for each quality-adjusted life-year gained from treatment. Sensitivity analysis shows that changing the discount rate substantially alters the cost-effectiveness, with a value of $1339 at a 0% discount rate and $56,250 at a 10% discount rate. CONCLUSIONS: Compared with therapeutic modalities for other disease entities, laser therapy for the treatment of extrafoveal CNV associated with ocular histoplasmosis appears to be a cost-effective treatment from the patient preference-based point of view.

Adult↗
PubMed2000

Implementation strategy: one-stop recovery for cardiac surgical patients.

"Fast-track" or "rapid recovery" for cardiac surgical patients is enjoying widespread use due to its benefits of increased patient comfort, enhanced quality of care, and cost-savings. Successful implementation of a fast-track program, however, may be challenged by physicians, the institution, or patients and their families. One-Stop Recovery is a fast-track program that emphasizes the benefits of traditional rapid recovery programs while addressing potential challenges.

Cardiac Surgical Procedures↗
PubMed2000

The cost-effectiveness of grid laser photocoagulation for the treatment of diabetic macular edema: results of a patient-based cost-utility analysis.

Grid laser therapy has been demonstrated to be of benefit for the treatment of diabetic macular edema. The purpose of the present study was to determine the cost-effectiveness of grid laser therapy for the treatment of diabetic macular edema. The analysis was performed from the perspective of a third-party insurer. Decision analyses and cost-effectiveness analyses were performed by incorporating the data from the Early Treatment Diabetic Retinopathy Study, expected longevity data, and patient-based utilities. Various sensitivity analyses were performed to determine the robustness of the models. Laser treatment conferred an overall improvement in quality-of-life adjusted years of approximately 3 months over the duration of disease for a hypothetical patient. The unadjusted cost per quality-of-life adjusted year (QALY) was US$3,101. Net present value analysis demonstrated that the cost per QALY could increase to $3,655, assuming a 5% discount rate. Overall, grid laser photocoagulation for diabetic macular edema is a very cost-effective treatment based on the results of this cost-utility analysis.

Adult↗
PubMed2000

Comparison of microembolism detected by transcranial Doppler and neuropsychological sequelae of carotid surgery and percutaneous transluminal angioplasty.

BACKGROUND AND PURPOSE: Percutaneous transluminal angioplasty (PTA) is currently being assessed for the treatment of carotid stenosis. In comparison with carotid endarterectomy (CEA), there is evidence of an increased risk of cerebral microembolism during the procedure. We have sought evidence of any neuropsychological sequelae of carotid PTA and compared it with CEA to demonstrate the relative safety of the 2 treatment options. METHODS: The neuropsychological outcomes after CEA and PTA were compared in 2 matched groups of patients with severe symptomatic carotid stenosis, 96% of whom had been randomized in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), at a single center. Transcranial Doppler insonation of the middle cerebral artery was used to measure cerebral reactivity in response to carbon dioxide inhalation before treatment and then to detect microembolization of the ipsilateral cerebral hemisphere and measure changes in blood flow velocity during the procedures. The performance on a neuropsychological test battery administered before, 6 weeks after, and 6 months after the procedure was compared in 20 patients undergoing PTA and 26 having CEA. RESULTS: At 6 weeks, 5 patients in each group showed a similar decline in neuropsychological performance; global measures showed no significant difference between the 2 procedures, despite a significantly higher incidence of microemboli during PTA. Both groups showed a marked reduction in anxiety after treatment. CONCLUSIONS: The findings provide some reassurance that PTA is not associated with greater cerebral complications than CEA, despite the higher embolic load recorded by transcranial Doppler ultrasonography during angioplasty.

Aged↗
PubMed2000

Aspirin or heparin in acute stroke.

Acute stroke treatment using aspirin and/or heparin was studied in the International Stroke Trial (IST) and Chinese Acute Stroke Trial (CAST) which randomised over 40,000 patients altogether. Combining the results demonstrated that aspirin (150-300 mg) given within 48 h of the onset of stroke produced a small but significant improvement in outcome (death or dependency) 4 weeks to 6 months after stroke of about 1 patient per 100 treated. There was a significant reduction in recurrent ischaemic stroke of similar degree, which was not associated with significant increase in cerebral haemorrhage. Therefore, aspirin should be used as early secondary prevention against recurrent stroke, after excluding cerebral haemorrhage by scanning the patient. Heparin does not improve clinical outcome after stroke even in patients in atrial fibrillation. It decreased recurrent ischaemic stroke significantly in IST, but at the cost of a significant increase in cerebral haemorrhage. Low molecular weight heparins and heparinoids have not proved any more beneficial. Therefore, heparin does not appear to be a useful routine therapy in acute stroke. The use of heparin should, therefore, be limited to patients at high risk of deep vein thrombosis or early recurrence.

Acute Disease↗
PubMed2000

Prevention of ischaemic stroke--antiplatelets.

Aspirin is the treatment of first choice for long-term secondary prevention of vascular events in patients with confirmed non-cardioembolic ischaemic stroke or TIA. However, there is no good evidence that it is of benefit in primary stroke prevention. If aspirin is contra-indicated, dipyridamole monotherapy is a relatively cheap, but slightly less effective, alternative. Aspirin and dipyridamole have an additive effect in secondary stroke prevention, but there is a high incidence of side effects and subsequent discontinuation of treatment with combination therapy. It is reasonable to consider clopidogrel for secondary prevention of vascular events in patients with ischaemic stroke who are intolerant of aspirin or dipyridamole, or who have a history of ischaemic heart disease. However, its cost is considerable. Over the next decade, oral antiplatelet agents directed against specific platelet receptors, or a combination of antiplatelet drugs inhibiting different aspects of platelet function, may improve secondary prevention of stroke.

Aspirin↗
PubMed2000

Analysis of costs.

Explore the source record for details and available documents.

Choroid Neoplasms↗
PubMed2000

Health care in the 21st century: evidence-based medicine, patient preference-based quality, and cost effectiveness.

The combination of evidence-based medicine, patient-based preferences using utility analysis, and econometric modeling yields a model to evaluate the incremental cost effectiveness of health care interventions. This methodology allows a comparison of the cost effectiveness of virtually all health care interventions and incorporates the patient voice to provide an information system that can improve the quality of health care and simultaneously reduce costs. It has been estimated that such an information system could save more than $90 billion per year of the annual $1.3 trillion health care bill in the United States.

Cost-Benefit Analysis↗
PubMed1999

Aging of the adult human brain: in vivo quantitation of metabolite content with proton magnetic resonance spectroscopy.

The purpose of this study was to examine the effect of aging on brain metabolite concentrations, including N-acetyl aspartate (NAA), the major marker of neurones, using short echo proton spectroscopy. Single-voxel proton spectra (TE 30 msec, TR 2 seconds) were obtained from white and gray matter using automated software (PROBE, G.E., Milwaukee, WI). Spectra were analyzed using the variable projection technique. Thirty healthy volunteers were studied within the age range 24-89 years. No significant trend in change of concentrations of NAA, total creatine, total choline or myo-inositol were seen with age. The total creatine concentration of parietal white matter in the over 60 age group (6.5 +/- 0.3 mmol/l) was significantly higher than the under 60 age group (6.0 +/- 0.4 mmol/l:; P < 0.05). No other significant difference between the two age groups was seen. The tissue concentration of the major neuronal marker, NAA, does not decline with age. No age-related changes in the concentrations of choline and myo-inositol and occipital gray matter total creatine were observed. These results provide a normal range of values for spectroscopically detectable metabolites within the regions studied, against which neurological diseases such as Alzheimer's disease can be compared in vivo.

Adult↗
PubMed1999

Utility values and diabetic retinopathy.

PURPOSE: To ascertain the utility values associated with diabetic retinopathy and varying degrees of visual loss. METHODS: One hundred consecutive patients with diabetic retinopathy and best-corrected visual acuity decreased to 20/40 or worse in at least one eye occurring primarily as a result of diabetic retinopathy were evaluated in a cross-sectional study. Utility values were ascertained in five groups using both the time trade-off and standard gamble methods: group 1 (best-corrected visual acuity in the better eye of 20/20 to 20/25), group 2 (best-corrected visual acuity in the better eye of 20/30 to 20/50), group 3 (best-corrected visual acuity in the better eye of 20/60 to 20/100), group 4 (best-corrected visual acuity in the better eye of 20/200 to 20/400), and group 5 (best-corrected visual acuity in the better eye of counting fingers to hand motions). RESULTS: The mean utility value for the diabetic retinopathy group as a whole was 0.77 (SD = 0.21; 95% confidence interval [CI], 0.73 to 0.81) with the time trade-off method and 0.88 (SD = 0.20; 95% CI, 0.84 to 0.92) with the standard gamble method. Employing the time trade-off method correlated with the best-corrected visual acuity in the better eye, the mean utility results were as follows: group 1 = 0.85 (95% CI, 0.75 to 0.95), group 2 = 0.78 (CI, 0.72 to 0.84), group 3 = 0.78 (CI, 0.67 to 0.89), group 4 = 0.64 (CI, 0.53 to 0.75), and group 5 = 0.59 (CI, 0.23 to 0.95). Thus, patients in group 1 (best-corrected visual acuity of 20/20 to 20/25 in the better eye) were willing to trade a mean of 15% of their remaining years of life in return for perfect vision in each eye, whereas those in group 5 (best-corrected visual acuity of counting fingers to hand motions in the better eye) were willing to trade a mean of 41% of their remaining years in return for perfect vision in each eye. There was no significant difference in mean utility values between patients who had decreased visual acuity from diabetic retinopathy for 1 year or less compared with those with decreased acuity for more than 1 year. There was also no significant difference in mean utility values between those with a 12th grade education or less compared with those with more than a 12th grade education. CONCLUSION: Visual loss occurring secondary to diabetic retinopathy is associated with a substantial decrease in patient utility value (and quality of life). The utility value is directly dependent on the degree of visual loss associated with the disease. The length of time of visual loss and amount of formal education do not appear to affect the utility value.

Adult↗
PubMed1999

Noradrenaline transporter gene transfer for radiation cell kill by 131I meta-iodobenzylguanidine.

Meta-iodobenzylguanidine conjugated to 131I-iodine is an effective agent for the targeted radiotherapy of tumors of neural crest origin which express the noradrenaline transporter (NAT). The therapeutic application of 131I MIBG is presently limited to the treatment of phaeochromocytoma, neuroblastoma, carcinoid and medullary thyroid carcinoma. To determine the feasibility of MIBG targeting for a wider range of tumor types, we employed plasmid-mediated transfer of the NAT gene into a human glioblastoma cell line (UVW) which does not express the NAT gene. This resulted in a 15-fold increase in uptake of MIBG by the host cells. A dose-dependent toxicity of 131I MIBG to the transfectants was demonstrated using three methods: (1) survival of clonogens derived from monolayer culture; (2) survival of clonogens derived from disaggregated multicellular spheroids; and (3) spheroid growth delay. 131I MIBG was twice as toxic to cells in spheroids compared with those in monolayers, consistent with a greater effect of radiation cross-fire (radiological bystander effect) from 131I beta-radiation in the three-dimensional tumor spheroids. The highest concentration of 131I MIBG tested (1 MBq/ml) was nontoxic to UVW control cells or spheroids transfected with the NAT gene in reverse orientation. These findings are encouraging for the development of NAT gene transfer-mediated 131I MIBG therapy.

3-Iodobenzylguanidine↗
PubMed1999

Blood lipid profile in ischaemia reperfusion injury.

BACKGROUND: Lipid components are considered to play an important role in ischaemia reperfusion injury although the mechanism of their action remains unknown. Accumulation of lipid metabolites in ischaemic tissues is a consistent observation, but exactly how these lipids are cleared from the tissues by the circulating blood during reperfusion is still open to speculation. In the present study, levels of blood lipids (fatty acids, phospholipids, triglycerides, cholesterol, lysolecithin and lysolecithin platelet activating factor (lyso PAF)) and the enzyme phospholipase A2 were determined in an experimental animal model (dogs) of ischaemic reperfusion injury. METHODS: The injury was induced by 4 h of aortic clamping followed by 2 h of reperfusion (unclamping). Blood samples were collected before clamping and at predetermined time intervals (0, 15, 60 and 120 min) after the release of clamp. The lipid contents were analysed and compared with sham-treated control dogs. RESULTS: The results showed significantly elevated levels of triglycerides and phospholipase A2, during ischaemia and reperfusion in experimental animals indicating tissue damage in the ischaemic phase continuing into the reperfusion phase and the risk of systemic damage from these toxic substances. Total fatty acid content in the circulating blood showed decreasing trends during the same time interval, which suggested possible reduced clearance of accumulated fatty acids from the affected tissues. Serum cholesterol, phospholipids, lyso PAF and lysolecithin did not show any significant variation compared with control dogs. CONCLUSIONS: It is possible that the delayed clearance of fatty acids may be due to the presence of fatty acids binding proteins in the ischaemic tissue, which trap these fatty acids in the tissues during ischaemic reperfusion injury. The prolonged retention of the accumulated fatty acids in the tissues in association with elevated triglycerides and phospholipase A2 activity may contribute to ischaemia reperfusion injury.

Animals↗
PubMed1999

Collaborative practice in the acute care setting.

As acute care nurse practitioners (ACNPs) become increasingly visible in tertiary care centers, clinical nurse specialists (CNSs) have begun to re-evaluate their unique contributions to patient care. While CNSs continue to be involved in indirect care provision, their direct care role is encountering increasing competition for the same patients from ACNPs. This article reviews the evolution of the ACNP and CNS roles and offers practical advice to both professionals on working together successfully, compatibility, and cohesively in an acute care setting.

Acute Disease↗