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D B Matchar

Publications and source records attributed to D B Matchar.

At least 19 recordsLinked to original sources
PubMed2005

Cost of multiple sclerosis by level of disability: a review of literature.

We performed a review of the economic literature to identify what is known about the relationship between Expanded Disability Status Scale (EDSS) categories and cost of multiple sclerosis (MS). We sought cohort studies of patients with multiple sclerosis that described the costs attributed to each EDSS score and utilized specific inclusion criteria for the selection of 10 studies. We found that both direct and indirect costs rise continuously with increasing EDSS category, and this rise is qualitatively exponential. The rise in indirect costs appears at lower EDSS scores. The cost of a relapse occurring in any given EDSS category exceeds that associated with that particular EDSS category. Few studies comprehensively assessed the entire spectrum of the costs, and much of the literature is based on EDSS categories in coarse groupings. In spite of several variations between studies, one important conclusion that we can draw is that rise in cost is positively correlated to scores on the EDSS categories, and therefore agents with a capacity to prevent or arrest the rate of MS progression may affect the overall cost of MS.

Disability Evaluation↗
PubMed2004

Meta-analysis: the detection of pancreatic malignancy with positron emission tomography.

BACKGROUND: Several factors contribute to the high mortality of pancreatic cancer, including limitations of diagnostic imaging. AIM: To perform a meta-analysis to assess the diagnostic accuracy of Fluro-deoxy-glucose positron emission tomography with computed tomography compared with computed tomography alone. METHODS: Articles were identified through a MEDLINE search and bibliography review. Summary estimates and receiver operating curves were calculated using Meta-Test 0.6. Publication bias and heterogeneity were assessed with a funnel plot and chi-squared test. RESULTS: The summary estimate and 95% confidence interval for sensitivity and specificity were as follows: computed tomography 81% (72-88%) and 66% (53-77%), PET after a positive computed tomography 92% (87-95%) and 68% (51-81%), PET after a negative computed tomography 73% (50-88%) and 86% (75-93%) and PET after an indeterminate computed tomography 100 and 68%. The area under the summary receiver operating curve was 0.82 for computed tomography and 0.94 for PET. There was no heterogeneity or publication bias. CONCLUSIONS: Our results suggest that although adding Fluro-deoxy-glucose positron emission tomography to the diagnostic work-up may enhance the diagnosis of pancreatic malignancy, its usefulness will vary depending upon the pretest probability of the patient, the results of computed tomography and the provider's testing thresholds. Further evaluation using a well-designed prospective study with a cost-effectiveness analysis is needed to clarify the appropriate role of Fluro-deoxy-glucose positron emission tomography.

Fluorodeoxyglucose F18↗
PubMed2003

VA Stroke Study: neurologist care is associated with increased testing but improved outcomes.

OBJECTIVE: VA Stroke Study (VASt) data were analyzed to determine whether neurologist management affected the process and outcome of care of patients with ischemic stroke. METHODS: VASt prospectively identified patients with stroke admitted to nine VA hospitals (April 1995 to March 1997). Demographics, stroke severity (Canadian Neurologic Score), stroke subtype (Trial of ORG 10172 in Acute Stroke Treatment [TOAST] classification), tests/procedures, and discharge status (independent, Rankin < or = 2, vs dead or dependent, Rankin 3 through 5) were compared between patients who were or were not cared for by a neurologist. RESULTS: Of 1,073 enrolled patients, 775 (neurologist care, n = 614; non-neurologist, n = 161) with ischemic stroke were admitted from home. Stroke severity (Canadian Neurologic Score 8.7 +/- 0.1 vs 8.4 +/- 0.2; p = 0.44), TOAST subtype (p = 0.55), and patient age (71.4 +/- 0.4 vs 72.4 +/- 0.7; p = 0.23) were similar for neurologists and non-neurologists. Neurologists more frequently obtained MRI (44% vs 16%; p < 0.001), transesophageal echocardiograms (12% vs 2%; p < 0.001), carotid ultrasounds (65% vs 57%; p = 0.05), cerebral angiography (8% vs 1%; p = 0.001), speech (35% vs 18%; p < 0.001), and occupational therapy (46% vs 33%; p = 0.005) evaluations. Brain CT, transthoracic echocardiogram, 24-hour ambulatory ECG use, and hospitalization durations (18.2 +/- 0.8 vs 19.7 +/- 4.1 days; p = 0.725) were similar. Neurologists' patients were less likely to be dead (5.6% vs 13.5%; OR = 0.38; 95% CI 0.22, 0.68; p = 0.001) and less likely to be dead or dependent (46.1% vs 57.1%; OR = 0.64; 95% CI 0.45, 0.92; p = 0.019) at the time of discharge. The benefit remained after controlling for stroke severity and comorbidity (OR = 0.63; 95% CI 0.42, 0.94; p = 0.025). CONCLUSION: Neurologist care was associated with more extensive testing, but similar lengths of hospitalization and improved outcomes.

Aged↗
PubMed2003

Racial differences in survival post cerebral infarction among the elderly.

OBJECTIVE: To investigate whether there are differences in poststroke survival between African American and white patients, aged 65 and over, in the United States. METHODS: A biracial cohort of patients was selected from a random 20% national sample of Medicare patients (age 65 and over) hospitalized with cerebral infarction in 1991, and was followed up to a period of 3 years. The Cox regression model was used for covariate adjustment. RESULTS: A total of 47,045 patients (including 5,324 African Americans) were identified for our analysis. Compared to white patients, African American patients on average were 6% more likely to die post cerebral infarction. The subpopulation analyses further suggest that African Americans age 65 to 74 had much lower 3-year survival probabilities (15 to 20%) than their white counterparts. CONCLUSIONS: The authors find evidence of racial disparities in survival post cerebral infarction among the elderly, although the differences by race are not as great as reported elsewhere for stroke incidence and mortality. Future analyses, using more clinically detailed data, should focus especially on whether survival differences by race persist in the young-old (age 65 to 74) population.

Black or African American↗
PubMed2001

Have randomized controlled trials of neuroprotective drugs been underpowered? An illustration of three statistical principles.

BACKGROUND AND PURPOSE: The results of phase III trials of neuroprotective drugs for acute ischemic stroke have been disappointing. We examine the question of whether these trials may have been underpowered. METHODS: Computer simulations were based on the binomial distribution. RESULTS: We illustrate that even small overestimates of the efficacy of an intervention can lead to a serious reduction in statistical power, that the use of data from phase II studies tends to lead to such overestimation, and that a minimum clinically important difference derived with cost-effectiveness modeling techniques is considerably smaller than might be suggested by intuition. CONCLUSIONS: We recommend placing more emphasis on minimum clinically important differences when planning stroke trials, with these differences being derived from an assessment of the public health impact obtained in conjunction with the use of epidemiological and cost-effectiveness models. Even small benefits, when averaged over a sufficiently large number of cases, will, in total, accrue to a large positive impact on the public health.

Brain Ischemia↗
PubMed2001

Improving the reliability of stroke subgroup classification using the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria.

BACKGROUND AND PURPOSE: We sought to improve the reliability of the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification of stroke subtype for retrospective use in clinical, health services, and quality of care outcome studies. The TOAST investigators devised a series of 11 definitions to classify patients with ischemic stroke into 5 major etiologic/pathophysiological groupings. Interrater agreement was reported to be substantial in a series of patients who were independently assessed by pairs of physicians. However, the investigators cautioned that disagreements in subtype assignment remain despite the use of these explicit criteria and that trials should include measures to ensure the most uniform diagnosis possible. METHODS: In preparation for a study of outcomes and management practices for patients with ischemic stroke within Department of Veterans Affairs hospitals, 2 neurologists and 2 internists first retrospectively classified a series of 14 randomly selected stroke patients on the basis of the TOAST definitions to provide a baseline assessment of interrater agreement. A 2-phase process was then used to improve the reliability of subtype assignment. In the first phase, a computerized algorithm was developed to assign the TOAST diagnostic category. The reliability of the computerized algorithm was tested with a series of synthetic cases designed to provide data fitting each of the 11 definitions. In the second phase, critical disagreements in the data abstraction process were identified and remaining variability was reduced by the development of standardized procedures for retrieving relevant information from the medical record. RESULTS: The 4 physicians agreed in subtype diagnosis for only 2 of the 14 baseline cases (14%) using all 11 TOAST definitions and for 4 of the 14 cases (29%) when the classifications were collapsed into the 5 major etiologic/pathophysiological groupings (kappa=0.42; 95% CI, 0.32 to 0.53). There was 100% agreement between classifications generated by the computerized algorithm and the intended diagnostic groups for the 11 synthetic cases. The algorithm was then applied to the original 14 cases, and the diagnostic categorization was compared with each of the 4 physicians' baseline assignments. For the 5 collapsed subtypes, the algorithm-based and physician-assigned diagnoses disagreed for 29% to 50% of the cases, reflecting variation in the abstracted data and/or its interpretation. The use of an operations manual designed to guide data abstraction improved the reliability subtype assignment (kappa=0.54; 95% CI, 0.26 to 0.82). Critical disagreements in the abstracted data were identified, and the manual was revised accordingly. Reliability with the use of the 5 collapsed groupings then improved for both interrater (kappa=0.68; 95% CI, 0.44 to 0.91) and intrarater (kappa=0.74; 95% CI, 0.61 to 0.87) agreement. Examining each remaining disagreement revealed that half were due to ambiguities in the medical record and half were related to otherwise unexplained errors in data abstraction. CONCLUSIONS: Ischemic stroke subtype based on published TOAST classification criteria can be reliably assigned with the use of a computerized algorithm with data obtained through standardized medical record abstraction procedures. Some variability in stroke subtype classification will remain because of inconsistencies in the medical record and errors in data abstraction. This residual variability can be addressed by having 2 raters classify each case and then identifying and resolving the reason(s) for the disagreement.

Acute Disease↗
PubMed2000

New transient ischemic attack and stroke: outpatient management by primary care physicians.

BACKGROUND: Patients with transient ischemic attack (TIA) or stroke frequently first contact their primary care physician rather than seeking care at a hospital emergency department. The purpose of the present study was to identify a group of patients seen by primary care physicians in an office setting for a first-ever TIA or stroke and characterize their evaluation and management. METHODS: Practice audit based on retrospective, structured medical record abstraction from 27 primary care medical practices in 2 geographically separate communities in the eastern United States. RESULTS: Ninety-five patients with a first-ever TIA and 81 with stroke were identified. Seventy-nine percent of those with TIA vs 88% with stroke were evaluated on the day their symptoms occurred (P =.12). Only 6% were admitted to a hospital for evaluation and treatment on the day of the index visit (2% TIA; 10% stroke; P =.03); only an additional 3% were admitted during the subsequent 30 days. Specialists were consulted for 45% of patients. A brain imaging study (computed tomography or magnetic resonance imaging) was ordered on the day of the index visit in 30% (23% TIA, 37% stroke; P =.04), regardless of whether the patient was referred to a specialist. Carotid ultrasound studies were obtained in 28% (40% TIA, 14% stroke; P<.001), electrocardiograms in 19% (18% TIA, 21% stroke; P =.60), and echocardiograms in 16% (19% TIA, 14% stroke; P =.34). Fewer than half of patients with a prior history of atrial fibrillation (n = 24) underwent anticoagulation when evaluated at the index visit. Thirty-two percent of patients (31% TIA, 33% stroke; P =.70) were not hospitalized and had no evaluations performed during the first month after presenting to a primary care physician with a first TIA or stroke. Of these patients, 59% had a change in antiplatelet therapy on the day of the index visit. CONCLUSIONS: Further primary care physician education regarding the importance of promptly and fully evaluating patients with TIA or stroke may be warranted, and barriers to implementation of established secondary stroke prevention strategies need to be carefully explored. Arch Intern Med. 2000;160:2941-2946

Aged↗
PubMed2000

Mathematical model for the natural history of human papillomavirus infection and cervical carcinogenesis.

The authors constructed a Markov model as part of a systematic review of cervical cytology conducted at the Duke University Evidence-based Practice Center (Durham, North Carolina) between October 1997 and September 1998. The model incorporated states for human papillomavirus infection (HPV), low- and high-grade squamous intraepithelial lesions, and cervical cancer stages I-IV to simulate the natural history of HPV infection in a cohort of women from ages 15 to 85 years. The age-specific incidence rate of HPV, and regression and progression rates of HPV and squamous intraepithelial lesions, were obtained from the literature. The effects of varying natural history parameters on cervical cancer incidence were evaluated by using sensitivity analysis. The base-case model resulted in a lifetime cervical cancer risk of 3.67% and a lifetime cervical cancer mortality risk of 1.26%, with a peak incidence of 81/100,000 at age 50 years. Age-specific distributions of precursors were similar to reported data. Lifetime risk of cancer was most sensitive to the incidence of HPV and the probability of rapid HPV progression to high-grade lesions (two- to threefold variations in risk). The model approximates the age-specific incidence of cervical cancer and provides a tool for evaluating the natural history of HPV infection and cervical cancer carcinogenesis as well as the effectiveness and cost-effectiveness of primary and secondary prevention strategies.

Adolescent↗
PubMed2000

Accuracy of the Papanicolaou test in screening for and follow-up of cervical cytologic abnormalities: a systematic review.

PURPOSE: To evaluate the accuracy of conventional and new methods of Papanicolaou (Pap) testing when used to detect cervical cancer and its precursors. DATA SOURCES: Systematic search of English-language literature through October 1999 using MEDLINE, EMBASE, other computerized databases, and hand searching. STUDY SELECTION: All studies that compared Pap testing (conventional methods, computer screening or rescreening, or monolayer cytology) with a concurrent reference standard (histologic examination, colposcopy, or cytology). DATA EXTRACTION: Two reviewers independently reviewed selection criteria and completed 2 x 2 tables for each study. DATA SYNTHESIS: 94 studies of the conventional Pap test and three studies of monolayer cytology met inclusion criteria. No studies of computerized screening were included. Data were organized by cytologic and histologic thresholds used to define disease. For conventional Pap tests, estimates of sensitivity and specificity varied greatly in individual studies. Methodologic quality and frequency of histologic abnormalities also varied greatly between studies. In the 12 studies with the least biased estimates, sensitivity ranged from 30% to 87% and specificity ranged from 86% to 100%. CONCLUSIONS: Insufficient high-quality data exist to estimate test operating characteristics of new cytologic methods for cervical screening. Future studies of these technologies should apply adequate reference standards. Most studies of the conventional Pap test are severely biased: The best estimates suggest that it is only moderately accurate and does not achieve concurrently high sensitivity and specificity. Cost-effectiveness models of cervical cancer screening should use more conservative estimates of Pap test sensitivity.

Cervix Uteri↗
PubMed2000

Quality of anticoagulation management among patients with atrial fibrillation: results of a review of medical records from 2 communities.

BACKGROUND: Most treatment of patients at risk for stroke is provided in the ambulatory setting. Although many studies have addressed the proportion of eligible patients with atrial fibrillation (AF) receiving warfarin sodium, few have addressed the quality of their anticoagulation management. OBJECTIVE: As a comprehensive assessment of quality, we analyzed the proportion of eligible patients receiving warfarin, the proportion of time their international normalized ratios (INRs) were within the target range, and, when an out-of-target range INR value occurred, the time until the next INR measurement was made. METHODS: Retrospective review of the medical records of 660 patients with AF managed by general internists and family practitioners in Rochester, NY, and the Research Triangle area of North Carolina. RESULTS: Only 34.7% of eligible patients with AF received warfarin. The INR values were out of the target range approximately half the time, and the response to these values was not always timely. For all the measures considered, both Rochester practices with access to an anticoagulation service had higher (albeit not ideal) quality of warfarin management than the remaining practices. CONCLUSIONS: We found significant deficiencies in the practice of warfarin management and suggestive evidence that anticoagulation services can partially ameliorate these deficiencies. More research is needed to describe the quality of anticoagulation management in typical practice and how this management can be improved.

Adult↗
PubMed2000

Setting the target for a better cervical screening test: characteristics of a cost-effective test for cervical neoplasia screening.

OBJECTIVE: To determine the potential effects on costs and outcomes of changes in sensitivity and specificity with new screening methods for cervical cancer. METHODS: Using a Markov model of the natural history of cervical cancer, we estimated the effects of sensitivity, specificity, and screening frequency on cost-effectiveness. Our estimates of conventional Papanicolaou test sensitivity of 51% and specificity of 97% were obtained from a meta-analysis. We estimated the effect of reducing false-negative rates from 40-90% and increasing false-positive rates by up to 20%, independently and jointly. We varied the marginal cost of improving sensitivity from $0 to $15. RESULTS: When specificity was held constant, increasing sensitivity of the Papanicolaou test increased life expectancy and costs. When sensitivity was held constant, decreasing specificity of the Papanicolaou test increased costs, an effect that was more dramatic at more frequent intervals. Decreased specificity had a substantial effect on cost-effectiveness estimates of improved Papanicolaou test sensitivity. Most of those effects are related to the cost of evaluation and treatment of low-grade lesions. CONCLUSION: Policies or technologies that increased sensitivity of cervical cytologic screening increased overall costs, even if the cost of the technology was identical to that of conventional Papanicolaou smears. These effects appear to be caused by relatively high prevalence of low-grade lesions and are magnified at frequent screening intervals. Efficient cervical cancer screening requires methods with greater ability to detect lesions that are most likely to become cancerous.

Adolescent↗
PubMed2000

Community impact of anticoagulation services: rationale and design of the Managing Anticoagulation Services Trial (MAST).

We describe the design of the Managing Anti-coagulation Services Trial (MAST), a practice-improvement trial testing whether anticoagulation services are a preferred method of managing anticoagulation for stroke prevention among patients with atrial fibrillation. Most randomized trials within the health care environment are designed as efficacy studies to determine what works under ideal conditions or ideal clinical practice. In contrast, effectiveness trials seek to generalize the results of efficacy studies by determining what works under more typical practice conditions. Practice-improvement trials are effectiveness trials that examine the management of a clinical problem in the context in which care is usually given. Noteworthy features of the MAST include defining the intervention in functional terms and collaboration with managed care organizations.

Aged↗
PubMed2000

Relationship between test frequency and outcomes of anticoagulation: a literature review and commentary with implications for the design of randomized trials of patient self-management.

BACKGROUND: Patient self-management (PSM) of anticoagulation, which is primarily based upon the premise that more frequent testing will lead to tighter anticoagulation control and thus to improved clinical outcomes, is a promising model of care. The goals of this paper are (1) to describe the strength of evidence correlating more frequent testing with improved outcomes; and (2) to discuss implications of these findings for the design of randomized controlled trials (RCTs) assessing the effectiveness and cost-effectiveness of PSM. METHODS: We performed two literature reviews: one examining the strength of the relationship between time in target range (TTR) and the clinical outcomes of major bleeding and thromboembolism; and the second examining the strength of the relationship between frequency of testing and TTR. RESULTS: We found that (1) the relationship between TTR and clinical outcomes is strong, thus supporting use of TTR as a primary outcome variable; and (2) more frequent testing seems to increase TTR, although the studies supporting this latter conclusion were relatively few and not definitive. Statistical analysis suggested that a study which uses clinical event rates as its primary outcome would need to be much larger than a comparable study which is based upon TTR. CONCLUSIONS: When designing randomized trials of PSM, the design should (1) use as its control group high quality anticoagulation management rather than usual care; (2) include the maximum possible amount of self-management in the intervention group; (3) include different testing intervals in the intervention group; (4) use TTR as the primary outcome variable and event rates as a secondary outcome; and (5) base the sample size calculations upon a 5-10% absolute improvement in TTR. Additional RCTs are needed in order to determine how the promise of PSM can best be fulfilled.

Anticoagulants↗