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Biomedical subjects

J Tsevat

Publications and source records attributed to J Tsevat.

At least 55 records · Page 3Linked to original sources
PubMed1991

Neonatal screening for sickle cell disease: a cost-effectiveness analysis.

PURPOSE: To determine the cost-effectiveness of screening newborn infants for sickle cell disease. DESIGN: We developed a decision model that examined two strategies: (1) screening neonates and administering penicillin to infants found to have sickle cell disease in the hope of preventing pneumococcal sepsis, and (2) not screening but administering penicillin to infants after symptoms of sickle cell disease develop. The model calculates the cost-effectiveness of these strategies during the first 3 years of life. We applied the model to three prototypic populations of neonates--black, nonblack with a relatively high prevalence of hemoglobin S genes, and nonblack with a low prevalence of hemoglobin S genes. DATA IDENTIFICATION: We obtained from the published literature the effectiveness and risk of penicillin prophylaxis, the risk of pneumococcal sepsis, and the probability that in infants not screened the development of symptoms would lead to the discovery of sickle cell disease within the first 3 years of life; we used the published literature and the Hardy-Weinberg law to determine the prevalence of sickle cell disease. We used actual variable costs of screening, antibiotic prophylaxis, and hospitalization for pneumococcal sepsis or anaphylaxis. RESULTS: Screening and then treating affected black infants costs only $3100 more per life saved than not screening. Screening nonblack populations with a high prevalence of hemoglobin S genes would cost $1.4 million per life saved, and screening low prevalence populations would cost $450 billion per life saved. CONCLUSIONS: Screening black infants is very worthwhile, but screening populations in which the hemoglobin S gene is rare is unjustified.

Anaphylaxis↗
PubMed1991

Which renal transplant patients should receive cytomegalovirus immune globulin? A cost-effectiveness analysis.

Our study objective was to determine the cost-effectiveness of prophylaxis with cytomegalovirus immune globulin for preventing CMV-associated disease in renal transplant patients. We used a decision analytic model applied to 5 groups of renal transplant recipients at varying risks of developing CMV-associated disease. We obtained the rates of developing CMV-associated disease, graft rejection, and mortality, and the effectiveness of CMV-IG from the published literature. We used actual variable costs of CMV-IG, hospitalization, dialysis, and outpatient follow-up. The incremental cost of administering CMV-IG compared with withholding it ranged from $29,800 per life saved for the highest risk group, CMV-seronegative recipients of kidneys from CMV-seropositive cadaveric donors, to $1.68 million per additional life saved for the lowest risk group, CMV-seronegative recipients of grafts from CMV-seronegative donors. The outcome was somewhat sensitive to the effectiveness of CMV-IG in preventing CMV-associated disease but not sensitive to wide variations in CMV-IG costs, dialysis costs, outpatient costs, and the probability of graft rejection. Our conclusion is that prophylaxis with CMV-IG is very worthwhile for renal transplant recipients at high risk of CMV-associated disease and is possibly worthwhile for some patients at lower risk. The cost-effectiveness of other strategies for preventing CMV-associated disease, such as prophylaxis with acyclovir, CMV vaccine, or unselected immune globulin, should be compared with CMV-IG.

Cost-Benefit Analysis↗
PubMed1991

Expected gains in life expectancy from various coronary heart disease risk factor modifications.

BACKGROUND: Despite much evidence that modifying risk factors for coronary heart disease can decrease morbidity and mortality, little is known about the impact of risk-factor modification on life expectancy. METHODS AND RESULTS: We used the Coronary Heart Disease Policy Model, a state-transition computer simulation of the US population, to forecast potential gains in life expectancy from risk-factor modification for the cohort of Americans turning age 35 in 1990. Among 35-year-old men, we projected that the population-wide increase in life expectancy would be about 1.1 years from strict blood pressure control, 0.8 years from smoking cessation, 0.7 years from reduction of serum cholesterol to 200 mg/dl, and about 0.6 years from weight loss to ideal body weight. For women, reducing cholesterol to 200 mg/dl would have the greatest estimated impact-a gain of 0.8 years-whereas smoking cessation, blood pressure control, or weight loss would yield population-wide gains of 0.7, 0.4, and 0.4 years, respectively. Gains for 35-year-old individuals having a given risk factor are greater. We estimate that, on average, male smokers would gain 2.3 years from quitting smoking; males with hypertension would gain 1.1-5.3 years from reducing their diastolic blood pressure to 88 mm Hg; men with serum cholesterol levels exceeding 200 mg/dl would gain 0.5-4.2 years from lowering their serum cholesterol level to 200 mg/dl; and overweight men would gain an average of 0.7-1.7 years from achieving ideal body weight. Corresponding projected gains for at-risk women are 2.8 years from quitting smoking, 0.9-5.7 years from lowering blood pressure, 0.4-6.3 years from decreasing serum cholesterol, and 0.5-1.1 years from losing weight. Eliminating coronary heart disease mortality is estimated to extend the average life expectancy of a 35-year-old man by 3.1 years and a 35-year-old woman by 3.3 years. CONCLUSIONS: Population-wide gains in life expectancy from single risk-factor modifications are modest, but gains to individuals at risk can be more substantial.

Adult↗
PubMed1989

Cost-effectiveness of antibiotic prophylaxis for dental procedures in patients with artificial joints.

We performed a cost-effectiveness analysis to evaluate whether patients with artificial joints should take penicillin, erythromycin, or no antibiotics before dental procedures. We modeled the risk of anaphylaxis from penicillin, the risks and consequences of an artificial joint infection, and the actual variable costs of hospitalization and antibiotics. Penicillin prophylaxis is slightly less expensive than erythromycin prophylaxis but is both more expensive and less effective than no prophylaxis. Erythromycin prophylaxis, the most effective, is the most expensive strategy. The marginal cost effectiveness of erythromycin prophylaxis compared to no prophylaxis is $12,900 per quality-adjusted year of life saved. Sensitivity analysis demonstrates that the risk of developing a joint infection is the key parameter in the analysis. Based on our estimated risk of developing a joint infection, the cost-effectiveness of antibiotic prophylaxis with erythromycin compares favorably with other medical interventions. Thus, until a definitive study to quantify the risk is conducted, patients with artificial joints should take prophylactic erythromycin when they undergo dental procedures.

Arthritis, Infectious↗
PubMed1988

Isoniazid for the tuberculin reactor: take it or leave it.

The management of the adult tuberculin reactor who has no other risk factors for the development of active tuberculosis is controversial. We performed a decision analysis to address the issue of whether adults 20 to 80 yr of age should take isoniazid to prevent the development of active disease. The analysis uses a Markov simulation, a regression model to calculate the risk of developing tuberculosis at any given time after the discovery of a positive skin test, and estimates from the literature for other probabilities. The analysis favors withholding INH for all age groups, but by only 4 to 17 days of life expectancy, depending on the age of the patient. Quality adjusting and discounting change neither the preferred strategy nor the closeness of the outcome. Sensitivity analyses also underscore the narrowness of the margin. Our analysis reaches different conclusions from previously published analyses. More important than the actual strategy preferred is the minute difference in expected utilities between administering and withholding INH. We suggest that the individual patient decide whether or not these differences are meaningful.

Adult↗
PubMedDate not supplied

What should be reported in a methods section on utility assessment?

BACKGROUND: The measurement of utilities, or preferences, for health states may be affected by the technique used. Unfortunately, in papers reporting utilities, it is often difficult to infer how the utility measurement was carried out. PURPOSE: To present a list of components that, when described, provide sufficient detail of the utility assessment. METHODS: An initial list was prepared by one of the authors. A panel of 8 experts was formed to add additional components. The components were drawn from 6 clusters that focus on the design of the study, the administration procedure, the health state descriptions, the description of the utility assessment method, the description of the indifference procedure, and the use of visual aids or software programs. The list was updated and redistributed among a total of 14 experts, and the components were judged for their importance of being mentioned in a Methods section. RESULTS: More than 40 components were generated. Ten components were identified as necessary to include even in an article not focusing on utility measurement: how utility questions were administered, how health states were described, which utility assessment method(s) was used, the response and completion rates, specification of the duration of the health states, which software program (if any) was used, the description of the worst health state (lower anchor of the scale), whether a matching or choice indifference search procedure was used, when the assessment was conducted relative to treatment, and which (if any) visual aids were used. The interjudge reliability was satisfactory (Cronbach's alpha = 0.85). DISCUSSION: The list of components important for utility papers may be used in various ways, for instance, as a checklist while writing, reviewing, or reading a Methods section or while designing experiments. Guidelines are provided for a few components.

Authorship↗
PubMedDate not supplied

Warfarin for dilated cardiomyopathy: a bloody tough pill to swallow?

Although current recommendations for the treatment of dilated cardiomyopathy include long-term anticoagulation to diminish the likelihood of systemic embolization, there have been no clinical trials examining the effectiveness of anticoagulation in preventing systemic embolization in these patients. Furthermore, those recommendations do not address the issue of the quality of life associated with long-term warfarin therapy. Using decision analysis, the authors examined the benefits and risks of long-term anticoagulation for patients 35 to 75 years of age who have dilated cardiomyopathy. The results show that anticoagulant therapy increases quality-adjusted life expectancy by 76 to 128 days, depending on the patient's age. Sensitivity analysis, however, demonstrates that the outcome is dependent on the disutility associated with long-term warfarin therapy. Interestingly, anticoagulation exerts most of its benefit by preventing pulmonary embolization, not systemic embolization. The authors conclude that the current recommendation to anticoagulate these patients, although probably correct for many patients, should take into consideration the change in lifestyle imposed by long-term anticoagulant therapy. For some patients, the benefit may not outweigh the sacrifice.

Adult↗
PubMedDate not supplied

Stability of time-tradeoff utilities in survivors of myocardial infarction.

To investigate whether time-tradeoff utilities of survivors of myocardial infarction change over time and whether changes in utilities correlate with changes in functional status, the authors conducted serial interviews using a time tradeoff and three measures of functional status in a cohort of 67 patients who had recently had myocardial infarction. The patients were also asked to rate their overall health on a rating scale and were asked about chest pain, exercise status, and employment status. Each patient was interviewed two to five times over one and a half years. The mean (95% CI) time-tradeoff score for all patients was 0.88 (0.84, 0.93). Over a mean interval of 8.4 months, 28 (42%) patients changed Karnofsky scores, 28 (42%) changed Specific Activity Scale classes, and 11 (16%) changed New York Heart Association classes, with most changes representing improvements in functional status. Scores on the rating scale improved by a mean (95% CI) of 0.06 [(0.03, 0.10); p < 0.002], but scores on the time tradeoff remained stable, with a mean (95% CI) change of 0.03 [(-0.02, 0.08); p = NS]. Changes in time-tradeoff scores did not correlate with changes in Specific Activity Scale classes (Kendall's tau = 0.21), New York Heart Association classes (tau = -0.02), or Karnofsky scores (tau = 0.14); with changes on the verbal rating scale (R = 0.20); with changes in chest pain status (tau = -0.05), exercise status (tau = 0.11), or employment status (tau = 0.11); or with interim hospitalizations (tau = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Finding the optimal multiple-test strategy using a method analogous to logistic regression: the diagnosis of hepatolenticular degeneration (Wilson's disease).

Finding the optimal strategy among a battery of tests may be cumbersome for decision analytic models. The authors present a method of examining multiple test combinations that is based on a modified Bayes' formula analogous to logistic regression. They examined all 16 combinations of four tests used to diagnose hepatolenticular degeneration. The four tests examined were: serum ceruloplasmin level, 24-hour urinary copper excretion, free serum copper level, and liver biopsy copper concentration. They also simulated the diagnostic workup of the disease for a hypothetical cohort of 15,000 patients at risk. Assuming the disutilities of false positives and false negatives to be equal, and considering sensitivity analysis of test characteristics, the following test combinations were found to be optimal for making the diagnosis at a prior probability of disease equal to 0.05: positive serum ceruloplasmin and 24-hour urinary copper excretion, combined with either positive liver biopsy or free serum copper (or both). The strategies obtained by the modified Bayes' formula were the same as those found using the simulated data set with a standard logistic-regression software package. The logistic model's diagnostic accuracy is 0.98 as measured by the area under the receiver operating characteristic curve. The optimal strategy for diagnosing hepatolenticular degeneration varies with the prior probability of disease. For prior probabilities of 0.05, 0.25, and 0.9, and the optimal strategy, model sensitivities are 0.801, 0.880, and 0.997, and model specificities are 0.991, 0.985, and 0.814, respectively. The new method provides a convenient alternative to decision trees when examining multiple diagnostic tests.

Area Under Curve↗
PubMedDate not supplied

Is experience a good teacher? How interns and attending physicians understand patients' choices for end-of-life care. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments.

BACKGROUND: Recent studies have shown that physicians do not accurately assess patients' health status or treatment preferences. Little is known, however, about how physicians' levels of training or experience relate to their abilities to assess these preferences. To better understand this phenomenon, the authors compared the abilities of medical interns and attending physicians to predict the choices of their adult patients for end-of-life care. METHODS: 230 seriously-ill adult inpatients were surveyed about their desires for cardiopulmonary resuscitation, their current quality of life, and their attitudes toward six other common adverse outcomes. The medical intern and attending physician who cared for these patients were asked to estimate the patient's responses for all of the same items. Agreement was assessed using the kappa statistic. RESULTS: Compared with interns, attending physicians had known patients longer, had talked with patients more frequently about prognosis, and felt they knew more about their patients' preferences (all p < .0001). Despite this, the attending physicians were no more accurate than the interns in assessing patients' preferences. Both interns and attending physicians had only a fair understanding of patients' preferences for cardiopulmonary resuscitation or their quality of life (kappa statistics 0.32 to 0.47), and even less understanding of their willingness to tolerate adverse outcomes (kappa statistics -0.03 to 0.37). CONCLUSIONS: For this cohort of seriously ill patients, neither medical interns nor their attending physicians were consistently accurate in assessing patients' preferences, and attending physicians were not more accurate than medical interns. Attending physicians should not assume that they can infer patients' preferences any better than the interns caring for these hospitalized patients.

Adult↗