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Biomedical subjects

M D Silverstein

Publications and source records attributed to M D Silverstein.

At least 91 records · Page 5Linked to original sources
PubMed1988

Life-sustaining treatment. A prospective study of patients with DNR orders in a teaching hospital.

We conducted a prospective survey of attending, resident, and intern physicians who had written a "do not resuscitate" (DNR) order for 93 patients in their care. After writing a DNR order, 11% of respondents would still use chest compression if their patient experienced a cardiopulmonary arrest. Many physicians did not plan to withdraw therapy except intensive care, but most physicians planned to withhold a spectrum of life-sustaining therapies, from hemodialysis (86%) to intravenous fluids (21%). Attending and house-staff physicians generally agreed on whether to withdraw a given therapy or not but frequently disagreed on whether to withhold a therapy or not. After patient discharge or death, 88 charts were reviewed. None of the 88 patients was coded. Physicians initiated 68 life sustaining therapies in 43 patients and discontinued 64 therapies in 34 patients; there was no change in management in 31 patients. We conclude that individual physicians interpret the DNR order differently. These orders often are associated with the discontinuation or noninitiation of life-sustaining therapies other than emergency CPR.

Adult↗
PubMed1988

The diagnosis of polyarteritis nodosa. I. A literature-based decision analysis approach.

We investigated diagnostic testing in polyarteritis nodosa (PAN) by calculating, from published data, the sensitivity and specificity of visceral angiography and muscle, nerve, testicle, kidney, and liver biopsy. Test sequence strategies were constructed by Bayesian inference using a computer program written for this purpose. Test sequences were compared with an aggressive strategy consisting of repeated tests until there was a positive finding or until the available tests were exhausted, and a conservative strategy consisting of 1 biopsy procedure plus angiography. The Bayesian analysis agreed most closely with the conservative approach for most prior probabilities (degree of suspicion) that a patient had PAN. The aggressive strategy had an overall sensitivity of 90% and specificity of 91%, whereas the conservative strategy was 85% sensitive and 96% specific. Furthermore, the aggressive strategy was more costly ($2,986 versus $1,961) and had a higher rate of morbidity (3.8 versus 2.7 days of hospitalization per patient evaluated) than did the conservative strategy. The mortality rates of both strategies were equivalent (approximately 0.05 deaths per hundred patients evaluated). The per-case cost of diagnosis increased as prevalence decreased, and at 10% prevalence, the aggressive strategy cost more than $17,000 per case diagnosed. Sensitivity analysis revealed that the strategies were moderately affected by the test characteristics, within reasonable assumptions, but that the differences in conservative and aggressive approaches remained. Thus, our analysis based on available data and the assumption of test independence suggests that the preferred diagnostic evaluation of patients with symptoms suggestive of PAN consists, in most cases, of a single biopsy procedure, with angiographic evaluation if necessary.

Costs and Cost Analysis↗
PubMed1988

The diagnosis of polyarteritis nodosa. II. Empirical verification of a decision analysis model.

We evaluated our literature-based estimates of diagnostic test characteristics and aggressive and conservative strategies for the diagnosis of polyarteritis nodosa (PAN) by reviewing 1980 through 1985 data from the University of Chicago Medical Center, Michael Reese Hospital, and Northwestern University Medical School. Test specificity was calculated by reviewing pathology and radiology reports on all relevant procedures done at the University of Chicago Medical Center in 1984 and 1985. There were no reports of false-positive findings (including angiography); thus, test specificity was 100% for muscle, nerve, kidney, liver, and testicular biopsy, which was comparable with our literature-based estimate of 97%. Test sensitivity was based on the 18 confirmed cases of PAN from the 3 institutions and was similar to that in published reports, ranging from 0% for liver biopsy to 100% for visceral angiography. Review of each case for diagnostic test sequence showed an average of 2 diagnostic procedures to confirm the diagnosis (range 1-6). Eight of 18 patients were evaluated according to the conservative strategy we proposed from our literature-based decision analysis approach. No patient was evaluated with the aggressive strategy, although 1 patient had 6 invasive procedures. Of the remaining 10 patients, 9 represented cases that might have been confirmed had the conservative approach been used, and if it had been used, 6 patients would have had the diagnosis confirmed. Thus, the minimum sensitivity of our conservative strategy is 78%, although based on these data, it could be as high as 100%.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗
PubMed1988

Prognosis in SLE: comparison of Markov model to life table analysis.

A Markov model of prognosis was evaluated by comparing the duration of disease activity states and life expectancy with Kaplan-Meier survival curves for 98 patients with systemic lupus erythematosus with 1080 patient-years of observation. A four state (remission, active, flare and death) homogeneous Markov chain was constructed to determine the transition probabilities between disease states, the probability of disease states over the subsequent 25 years, time in each disease state, and life expectancy. Approximately 85% of the clinical course of patients was in the active disease state; no patient made a transition directly between remission and flare; virtually all deaths occurred from the flare disease state. The proportion of the patient population in each disease state over time provided a convenient graphic summary of the natural history of SLE that supplemented the Kaplan-Meier survival curves. A Markov model analysis yields a clinically useful description of outcome for multistate diseases that supplements survival curves.

Actuarial Analysis↗
PubMed1988

The diagnosis of neoplasia in patients with asymptomatic microscopic hematuria: a decision analysis.

Clinical decision analysis and a computer model were used to evaluate the performance of alternative strategies for the diagnosis of neoplasia in adults with asymptomatic microscopic hematuria. Strategies consisted of sequences of diagnostic tests, including ultrasound, excretory urography, angiography, computerized tomography and cystoscopy. The strategies have a sensitivity of 98 to 100 per cent for bladder cancer and 90 to 94 per cent for renal carcinoma, and a specificity of 99 per cent. The cost per carcinoma diagnosed is $75,000 to $86,000 at 1 per cent prevalence and $5,000 to $5,800 at 15 per cent prevalence. Strategies using cystoscopy or ultrasound as the initial diagnostic test minimized cost and morbidity while maintaining diagnostic accuracy. Excretory urography does not add significantly to diagnostic accuracy but it does add to cost and morbidity.

Adult↗
PubMed1988

Optimal timing of colonoscopy to screen for cancer in ulcerative colitis.

Patients with ulcerative colitis have a high risk of colon cancer that increases with duration of disease. Annual colonoscopy with biopsies for 99 patients with pancolitis and a mean duration of disease at entry of 17 years was evaluated. The outcomes of mucosal dysplasia or cancer were analyzed to determine the annual risk (hazard rate) of high-grade dysplasia or colon cancer. The hazard rates were used to recommend screening intervals. The delay in the diagnosis of cancer is minimized for any given number of tests when the time between tests is inversely proportional to the square root of the hazard rate. Since the hazard rate for cancer increases with duration of disease, intervals for screening tests should not be uniform. For a range of reasonable marginal benefits from additional testing, the number of tests recommended is less than the number of tests done in fixed-interval screening programs. Scheduling screening tests using patient-specific hazard rates to minimize the delay in the diagnosis of cancer reduces the number of colonoscopies, associated cost, and morbidity.

Adolescent↗
PubMed1988

Microscopic hematuria.

Microscopic hematuria is a common problem that may affect up to 13 per cent of the population. The number of RBCs identified in the urine sediment is dependent, in part, upon the technique used in performing the urinalysis. The exact number of RBCs normally excreted into the urine has been difficult to establish. However, three to eight RBCs per HPF would be accepted by most investigators as an acceptable dividing point between normal and abnormal hematuria. Although the prevalence of microscopic hematuria in the general population is high, the number of patients who have serious urologic disease is low. Many diagnostic algorithms are available for evaluating these patients, but at the present time there is still uncertainty regarding how extensive the evaluation should be for patients with asymptomatic microscopic hematuria.

Algorithms↗
PubMed1987

Chronic cholecystitis. An analysis of diagnostic strategies.

To define the optimal diagnostic approach for suspected chronic cholecystitis comprehensive management strategies were developed. Using a computer model, the frequency of appropriate surgery, inappropriate surgery, complications, death, and medical costs were compared in populations of patients with various disease prevalences. The optimal strategy began with ultrasonography, followed by an oral cholecystogram when the ultrasonogram was inconclusive. Oral cholecystogram also was employed when additional diagnostic studies failed to provide another explanation for the patient's symptoms. Compared with strategies using only ultrasonography or oral cholecystography, the combination strategy lowered the frequency of inappropriate surgery from 7.1 to 4.4% and direct medical costs from $1,877 to $1,766 per patient in a population with a 20% prevalence of chronic cholecystitis. The differences persisted at higher prevalences of cholecystitis and when sensitivities and specificities of the tests were varied over ranges reported in the literature. Diagnostic accuracy and direct medical costs could be improved by a more frequent interpretation of subtle abnormal ultrasonographic findings as inconclusive and by a more liberal use of oral cholecystography. This analysis demonstrates that a strategy combining ultrasonography and oral cholecystography is superior to the use of either test alone and is cost-efficient.

Cholecystitis↗
PubMed1983

The cost-effectiveness of hepatitis B vaccine.

We evaluated the cost-effectiveness of different strategies for use of hepatitis B vaccine. For populations with high prevalences of immunity and high attack rates, screening for prior immunity and vaccinating susceptibles is the lowest cost strategy. For populations with low prevalences of immunity but with high attack rates, vaccination without screening is most cost-saving. For populations with low prevalences of immunity and low attack rates, a non-vaccination policy is least costly. Vaccination will be cost-saving for populations with annual attack rates of five per cent, if direct medical costs only are considered or, for populations with annual attack rates on the order of one per cent, if indirect medical costs are included.

Cost-Benefit Analysis↗
PubMed1983

A clinical decision analysis program for the Apple computer.

A computer program written in BASIC and implemented on a 48K RAM Apple II computer was developed to assist physicians in using decision analysis to solve clinical problems. Clinicians familiar with decision analysis can easily enter, modify, store, and retrieve decision trees. Probabilities and utilities can be calculated and a sensitivity analysis can be performed and printed. An entire decision tree can be listed, and a graphic display of any node with its branches, branch probabilities, and node utilities can be viewed and printed. The program is easy to use and can be learned in a few hours. Its flexibility and power will facilitate the application of decision analysis to a wide variety of clinical problems.

Computers↗
PubMed1983

Suspected obstructive jaundice: a decision analysis of diagnostic strategies.

Clinical decision analysis and a computer model were used to evaluate ten diagnostic strategies for the diagnosis of extrahepatic obstructive jaundice. The sensitivity, specificity, complications, and costs of currently used individual tests were used to determine the overall sensitivity, specificity, complications, and costs of each strategy at different disease prevalences. In patients with a low probability of extrahepatic obstructive jaundice (less than or equal to 20%), the optimal strategy begins with ultrasonography, followed by a cholangiogram when dilated ducts are present. When dilated ducts are not present, patients may be observed clinically and endoscopic retrograde cholangiopancreatography is done if the jaundice does not resolve. In patients with a higher probability of extrahepatic obstructive jaundice, a cholangiogram is needed for an accurate diagnosis. In patients with a low probability of extrahepatic obstructive jaundice, the optimal strategy has an overall sensitivity of 92% and a specificity of 99%. About 40% of patients need a cholangiogram at an average cost of $1000 per patient. In patients with a higher probability of extrahepatic obstructive jaundice, the optimal strategy has an overall sensitivity of 97%, specificity of 98%, and cost of $1000 to $1200 per patient.

Biopsy↗
PubMed1982

Patients with syncope admitted to medical intensive care units.

The records of 108 patients admitted to a medical intensive care unit (ICU) for syncope during a two-year period were reviewed. Explicit criteria were used to classify patients by presumed etiologic diagnosis. Thirty-six percent of the cases of syncope were due to cardiovascular disease, 17% were due to noncardiovascular disease, and 47% were unexplained at hospital discharges. Seventy-two percent of presumed etiologic diagnoses were based on information available at the time of patient admission. The remainder were based on ICU monitoring and additional diagnostic tests. Patients were prospectively studied after hospital discharge. The one-year mortality was 19% in the cardiovascular group, 6% in the noncardiovascular group, and 6% among patients whose syncope remained unexplained. Age-standardized comparisons between the unexplained syncope group, the US population, and other ICU patients suggest that patients with syncope unexplained at hospital discharge do not have an increased risk of death during the subsequent year.

Cardiovascular Diseases↗
PubMed1982

Indications for use of hepatitis B vaccine, based on cost-effectiveness analysis.

To formulate indications for the use of hepatitis B vaccine, we examined the cost effectiveness of three strategies: vaccinating everyone; screening everyone and vaccinating those without evidence of immunity; and neither vaccinating nor screening, but passively immunizing those with known exposure. Estimates of the hepatitis attack rate, prevalence of immunity, and frequency of known exposure were made for three representative populations: homosexual men, surgical residents, and the general population of the United States. Screening followed by vaccination of homosexual men and vaccination without prior screening of surgical residents would result in savings of medical costs. Neither screening nor vaccination is the lowest-cost strategy for the general population. Vaccination of susceptible persons will save medical costs for populations with annual attack rates above 5 per cent. Vaccination may be considered cost effective (or cost saving when indirect costs are included) for populations with attack rates as low as 1 to 2 per cent.

Cost-Benefit Analysis↗
PubMedDate not supplied

Long-term use of oral anticoagulants and the risk of fracture.

BACKGROUND: Vitamin K participates in bone metabolism and, since oral anticoagulants antagonize vitamin K, their use may increase the risk of osteoporosis. OBJECTIVE: To evaluate fracture risk at all skeletal sites following exposure to oral anticoagulants. METHODS: In a population-based retrospective cohort study, 572 Olmsted County, Minnesota, women 35 years or older at their first lifetime venous thromboembolism event between 1966 and 1990 were followed up for fractures. Risk was assessed by comparing new fractures with the number expected from sex- and age-specific fracture incidence rates for the general population (standardized incidence ratio [SIR]). RESULTS: Altogether, 480 fractures occurred during 6314 person-years of follow-up. Increasing exposure to oral anticoagulation was associated with an increased SIR for vertebral fractures: at less than 3 months of exposure, 2.4 (95% confidence interval [CI], 1.6-3.4); 3 to less than 12 months, 3.6 (95% CI, 2.5-4.9); and 12 months or more, 5.3 (95% CI, 3.4-8.0); and for rib fractures: at less than 3 months, 1.6 (95% CI, 0.9-2.7); 3 to less than 12 months, 1.6 (95% CI, 0.9-2.6); and 12 months or more, 3.4 (95% CI, 1.8-5.7). The data revealed no increased risk for other types of fractures. Oral anticoagulation for 12 months or more was an independent predictor of vertebral fractures (P = .009) and rib fractures (P = .02), but not other fractures. CONCLUSIONS: Long-term exposure to oral anticoagulation is associated with an increased risk of vertebral and rib fractures. The mechanism by which this occurs is still unclear and needs further investigation.

Administration, Oral↗
PubMedDate not supplied

Costs, charges, and reimbursements for persons with sickle cell disease.

PURPOSE: The aims of this study were to describe health care costs and charges for patients with sickle cell disease (SCD) and identify predictors of high use. PATIENTS AND METHODS: Patients with SCD were identified by International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) codes from a university hospital's administrative databases from January 1, 1996, to September 30, 1997. Clinical and administrative data were gathered on each patient for all hospital admissions and ambulatory clinic visits. Logistic regression models were used to determine predictors of high health care use. RESULTS: A total of 947 patients with SCD were identified, 73% of whom resided within three South Carolina counties. On average, there were 0.9 admissions per patient per year and 8.0 outpatient visits per patient per year. Mean inpatient hospital charges, physician charges, and direct hospital costs per admission were $7290, $1589, and $5405, respectively, and the average length of stay was 4.5 days. Mean hospital charges, physician charges, and direct hospital costs per outpatient visit were $305, $169, and $688, respectively. Forty percent of the inpatient hospital charges were accounted for by only 4.2% of the patients. Residing in a distant county and being admitted with a diagnosis of painful respiration were found to be predictors of excessive charges and expenses beyond expected reimbursements. CONCLUSIONS: Patients with SCD are frequent users of health care services. Charges and costs are distributed disproportionately across these patients. Predictors of excessive hospital charges include living geographically distant from the hospital and being admitted with a diagnosis of painful respiration.

Adolescent↗
PubMedDate not supplied

Should donor blood be screened for elevated alanine aminotransferase levels? A cost-effectiveness analysis.

We examined the cost-effectiveness of alanine aminotransferase (ALT) screening of donor blood to prevent non-A, non-B posttransfusion hepatitis. Based on estimated costs of ALT screening, blood replacement, and medical evaluation of donors with high ALT levels, we concluded that screening at an ALT level of 45 IU would cost $3.82 per unit. In a population requiring an average of 3.7 units per transfusion, one case of hepatitis would be prevented for every 115 units screened, resulting in a cost of $439 per case prevented. With an estimated direct medical cost of $1,181 per case of non-A, non-B hepatitis, expected net savings for each case prevented would be $742. Screening at other ALT thresholds would be less cost-saving. Sensitivity analyses indicate that screening would be cost-saving for a wide range of cost estimates and number of units per transfusion. Alanine aminotransferase screening is warranted until more sensitive and specific screening tests for transmissibility of non-A, non-B hepatitis become available.

Alanine Transaminase↗