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Biomedical subjects

N A Solomon

Publications and source records attributed to N A Solomon.

At least 19 recordsLinked to original sources
PubMed1999

Cost-effectiveness of alternative test strategies for the diagnosis of coronary artery disease.

BACKGROUND: The appropriate roles for several diagnostic tests for coronary disease are uncertain. OBJECTIVE: To evaluate the cost-effectiveness of alternative approaches to diagnosis of coronary disease. DESIGN: Meta-analysis of the accuracy of alternative diagnostic tests plus decision analysis to assess the health outcomes and costs of alternative diagnostic strategies for patients at intermediate pretest risk for coronary disease. DATA SOURCES: Studies of test accuracy that met inclusion criteria; published information on treatment effectiveness and disease prevalence. TARGET POPULATION: Men and women 45, 55, and 65 years of age with a 25% to 75% pretest risk for coronary disease. TIME HORIZON: 30 years. PERSPECTIVE: Societal. INTERVENTIONS: Diagnostic strategies were initial angiography and initial testing with one of five noninvasive tests--exercise treadmill testing, planar thallium imaging, single-photon emission computed tomography (SPECT), stress echocardiography, and positron emission tomography (PET)--followed by coronary angiography if noninvasive test results were positive. Testing was followed by observation, medical treatment, or revascularization. OUTCOME MEASURES: Life-years, quality-adjusted life-years (QALYs), costs, and costs per QALY. RESULTS OF BASE-CASE ANALYSIS: Life expectancy varied little with the initial diagnostic test; for a 55-year-old man, the best-performing test increased life expectancy by 7 more days than the worst-performing test. More sensitive tests increased QALYs more. Echocardiography improved health outcomes and reduced costs relative to stress testing and planar thallium imaging. The incremental cost-effectiveness ratio was $75,000/QALY for SPECT relative to echocardiography and was greater than $640,000 for PET relative to SPECT. Compared with SPECT, immediate angiography had an incremental cost-effectiveness ratio of $94,000/QALY. RESULTS OF SENSITIVITY ANALYSIS: Qualitative findings varied little with age, sex, pretest probability of disease, or the test indeterminancy rate. Results varied most with sensitivity to severe coronary disease. CONCLUSIONS: Echocardiography, SPECT, and immediate angiography are cost-effective alternatives to PET and other diagnostic approaches. Test selection should reflect local variation in test accuracy.

Adult↗
PubMed1997

Cost-effectiveness of screening for carotid stenosis in asymptomatic persons.

BACKGROUND: The Asymptomatic Carotid Atherosclerosis Study (ACAS) showed that carotid endarterectomy was beneficial for symptom-free patients with carotid stenosis of 60% or more. This finding raises the question of whether widespread screening to identify cases of asymptomatic carotid stenosis should be implemented. OBJECTIVE: To determine whether a screening program to identify cases of asymptomatic carotid stenosis would be a cost-effective strategy for stroke prevention. DESIGN: Cost-effectiveness analysis using published data from clinical trials. SETTING: General population of asymptomatic 65-year-old men. INTERVENTION: Patients who were screened for carotid disease with duplex Doppler ultrasonography were compared with patients who were not screened. If ultrasonography found significant carotid stenosis (> or = 60%), disease was confirmed by angiography before carotid endarterectomy was done. MEASUREMENTS: Quality-adjusted life-years, costs, and marginal cost-effectiveness ratios. RESULTS: When the conditions and results of ACAS were modeled and it was assumed that the survival advantage produced by endarterectomy would last for 30 years, the lifetime marginal cost-effectiveness of screening relative to no screening was $120,000 per quality-adjusted life-year. Sensitivity analysis showed that marginal cost-effectiveness decreased to $50,000 or less per quality-adjusted life-year only under implausible conditions (for example, if a free screening instrument with perfect test characteristics was used or an asymptomatic population with a 40% prevalence of carotid stenosis was found). CONCLUSIONS: Surgery offers a real but modest absolute reduction in the rate of stroke at a substantial cost. A program to identify candidates for endarterectomy by screening asymptomatic populations for carotid stenosis costs more per quality-adjusted life-year than is usually considered acceptable.

Aged↗
PubMed1994

Patient preferences for stroke outcomes.

BACKGROUND AND PURPOSE: In clinical trials stroke is reported as a major morbid outcome, but the impact of stroke on patients is not directly assessed. This study examines patient preferences for different outcomes of stroke, including death. METHODS: We presented patients with written case scenarios of stroke outcomes. The scenarios represented four categories of stroke severity (mild, moderate, severe, and fatal), and for nonfatal strokes the scenarios described motor, language, and cognitive deficits. Patients reported values for each of the 10 stroke scenarios using a rank-and-scale method over a 100-point range, with 100 representing perfect health and 0 corresponding to the worst possible health state. RESULTS: One hundred seventeen of 209 consecutive patients at risk for stroke participated in this study. Severe strokes were uniformly rated as having low preference weights (mean +/- SD [median]: 3 +/- 4 [1] for disabling hemiplegia, 8 +/- 9 [5] for confusion, and 15 +/- 14 [10] for global aphasia), and severe motor impairment (a disabling hemiplegia) was rated as significantly worse than death. Even mild deficits resulted in substantial loss to patients (54 +/- 21 [55] for dysarthria and 53 +/- 21 [50] for mild anomia). CONCLUSIONS: Strokes may result in a wide variety of post-stroke consequences for patients. Severe strokes may be viewed by patients as tantamount to or worse than death. Even mild strokes may cause significant declines in patient preferences for health states. These data are useful in interpreting studies that report stroke and death, in designing new studies that measure stroke in at-risk populations, and in helping patients reach treatment decisions about therapies designed to prevent strokes.

Aged↗
PubMed1993

What are representative survival rates for out-of-hospital cardiac arrest? Insights from the New Haven (Conn) experience.

BACKGROUND: Survival rates from out-of-hospital cardiac arrests due to ventricular fibrillation or pulseless ventricular tachycardia vary greatly. The majority of published reports indicate a survival range from 11% to 33%, depending on the area of observation. Two recent series from major metropolitan centers describe markedly less favorable outcomes and have led to speculation that dense urbanization may contribute to worse outcomes. METHODS: Examination of a consecutive series of out-of-hospital cardiac arrests in New Haven, Conn, a city of 127,000 people and 55 km2 with a two-tiered emergency response system. All cases of nontraumatic cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia occurring outside of a hospital between January 1988 and June 1989 were considered. That city's emergency medical system employs emergency medical technicians and paramedics. Standard resuscitation techniques were employed; high-dose epinephrine and interposed abdominal counterpulsations were not routine interventions. The main outcome measure was survival to hospital discharge. RESULTS: Three (4.0%) of 75 patients survived cardiac arrest and were discharged alive from the hospital. Two (5.3%) of 38 witnessed arrests resulted in hospital discharges. Patient demographics were typical of those reported from other cities that have published outcomes data. Few patients (16%) received bystander-initiated cardiopulmonary resuscitation. CONCLUSION: There is increasing evidence that previously recognized standards for resuscitation success may not be present in certain types of municipalities, including this northeastern city. A registry of outcomes from out-of-hospital cardiac arrests would help to clarify the true national experience.

Connecticut↗
PubMed1992

Genetic and molecular analysis of DNA43 and DNA52: two new cell-cycle genes in Saccharomyces cerevisiae.

Two Saccharomyces cerevisiae genes previously unknown to be required for DNA synthesis have been identified by screening a collection of temperature-sensitive mutants. The effects of mutations in DNA43 and DNA52 on the rate of S phase DNA synthesis were detected by monitoring DNA synthesis in synchronous populations that were obtained by isopycnic density centrifugation. dna43-1 and dna52-1 cells undergo cell-cycle arrest at the restrictive temperature (37 degrees C), exhibiting a large-budded terminal phenotype; the nuclei of arrested cells are located at the neck of the bud and have failed to undergo DNA replication. These phenotypes suggest that DNA43 and DNA52 are required for entry into or completion of S phase. DNA43 and DNA52 were cloned by their abilities to suppress the temperature-sensitive lethal phenotypes of dna43-1 and dna52-1 cells, respectively. DNA sequence analysis suggested that DNA43 and DNA52 encode proteins of 59.6 and 80.6 kDa, respectively. Both DNA43 and DNA52 are essential for viability and genetic mapping experiments indicate that they represent previously unidentified genes: DNA43 is located on chromosome IX, 32 cM distal from his5 and DNA52 is located on chromosome IV, 0.9 cM from cdc34.

Amino Acid Sequence↗
PubMed1989

Risk of carotid endarterectomy in the elderly.

We used the Medicare claims files to describe operative mortality for 2,089 New England residents over the age of 65 who underwent carotid endarterectomy in 1984 and 1985. For patients ages 65 to 69, the risk of death within 30 days of surgery was 1.1 percent, (95% confidence interval = 0.5, 2.1), for those ages 70 to 74, 2.8 percent (1.7, 4.4), for those ages 75 to 79, 3.2 percent (1.8, 5.2), and for those over age 80, 4.7 percent (2.3, 8.5). Nearly 80 percent of patients underwent surgery at hospitals performing 40 or fewer carotid endarterectomies per year on the Medicare population. The adjusted odds ratio for 30 day mortality for patients undergoing surgery in these low-volume hospitals was 2.8 (95% CI = 1.1, 7.2) compared to higher volume hospitals. Although the Medicare claims data provided only limited data about post-operative strokes, analysis of post-operative stroke risk supported these findings.

Age Factors↗
PubMed1987

Differences between early and late onset of substance abuse: an inpatient experience.

Of 100 consecutive patients admitted to an inpatient alcohol and drug abuse ward, approximately four fifths reported the onset of substance use before 18 years of age. The majority used both alcohol and drugs, and had a history of problems with school authorities and suicidal ideation. We found general and sex-specific patterns of substance use among both depressed and nondepressed substance users and abusers.

Adolescent↗
PubMed1986

Technetium-sulfur colloid.

The chemistry of the technetium-sulfur colloid produced by the reaction of sodium thiosulfate with acid was investigated. A commercial kit was duplicated, and analyses of elemental sulfur, bisulfite and residual thiosulfate were carried out. The colloidal dispersions were filtered through Nuclepore graded membranes, and the percentages of sulfur and of 99mTc in the various filtrates were determined. In all cases--with varying acid, thiosulfate and time of incubation--there was a rough agreement between the two percentages for particles 0.4 micron in diameter or more. However, for small particles (less than 0.1 micron) there was virtually no sulfur, but there was an appreciable percentage of technetium. It was concluded that the technetium sulfide nuclei formed first, and that the supersaturated sulfur deposited in part on them and in part on its own nuclei. It was found that raising the pH of the preparation to weakly alkaline values and reheating the solution dissolved most of the deposited sulfur by the reaction with sulfite to form thiosulfate, leaving much smaller, virtually sulfur-free technetium sulfide particles. Such a preparation was found to be as efficient as the technetium-antimony sulfide colloid for lymphograms in dogs. Potassium trithionate, K2S3O6, used in place of sodium thiosulfate, produced small Tc-S colloid particles with less sulfur than the conventional thiosulfate-acid system.

Animals↗
PubMed1986

Scintiscan for acute intrascrotal conditions.

The efficacy and merit of testicular imaging, utilizing Tc-99m pertechnetate, were studied prospectively in a group of patients who presented with acute onset of scrotal pain. Consecutive admissions were studied. All were managed according to the likelihood of the problem being testicular torsion, which was determined from the clinical history, physical examination and the routine laboratory data. The final diagnostic outcome, whether by surgical exploration or clinical progress with conservative treatment, is collated with the preoperative scintigraphic interpretations, made with respect to predefined criteria. Analysis of the pretreatment images obtained in 57 patients shows that the radionuclide study is highly reliable in cases of testicular torsion and epididymo-orchitis. It appears to be much less dependable, however, in the other acute scrotal conditions. Torsions that are intermittent in nature or corrected manually apparently can have variable presentations. Certain difficulties and potential pitfalls encountered in interpreting the scintigraphic studies are discussed.

Abscess↗
PubMed1984

Repression of beta-lactam production in Cephalosporium acremonium by nitrogen sources.

A variety of inorganic and organic nitrogen sources were added to fermentation media to determine their regulatory effects on the production of beta-lactam antibiotics by Cephalosporium acremonium. (NH4)2SO4 at concentrations higher than 100 mM (1.3%) strongly inhibited beta-lactam production. L-Asparagine and L-arginine proved to be the best nitrogen sources tested for beta-lactam production. The optimum concentration of asparagine was 1.2%. Higher concentrations led to NH3 accumulation, increase in pH, and lower growth rates. Addition of tribasic magnesium phosphate [Mg3(PO4)2 X 8H2O] to the (NH4)2SO4-containing medium stimulated beta-lactam production markedly and ammonium repression of the ring-expansion enzyme was reversed. It appears that the ring-expansion step is a very sensitive part of beta-lactam biosynthesis in C. acremonium with respect to nitrogen source repression. Other enzymes may also be sensitive in view of the fact that nitrogen source derepression not only led to increases in cephalosporin C but, to a lesser extent, penicillin N and total beta-lactam titers.

Acremonium↗
PubMed1983

Scintigraphic demonstration of tracheo-esophageal fistula.

A tracheo-esophageal fistula, developed following radiotherapy for an esophageal carcinoma, was vividly demonstrated by radionuclide imaging. The abnormality was later confirmed by a barium esophagram and endoscopic examinations. The scintigraphic procedure, making use of a Tc-99m sulfur colloid swallow, appears to be a simple alternative method that may be clinically useful for the diagnosis of such a condition.

Barium Sulfate↗
PubMed1981

Scintigraphic pattern in missed testicular torsion.

The testicular scintigraphic findings of nine patients with surgically and pathologically proved torsion of the testis of over 24 hours duration are reviewed. In the delayed blood-pool images each showed the classical avascular twisted testicle with a variable peripheral rim of hyperemia. In the dynamic blood-flow phase, eight revealed a perceptible increase of vascular perfusion in the scrotal region on the affected side, in addition to the testicular radionuclide angiogram peculiarities previously described for missed testicular torsion. This pattern of perfusion was seen only in torsion of over one day duration. A low salvage probability is expected in these cases.

Adolescent↗