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Biomedical subjects

A S Detsky

Publications and source records attributed to A S Detsky.

At least 55 records · Page 3Linked to original sources
PubMed1995

A clinician's guide to utility measurement.

The approach described in this article is designed for clinicians who are striving to read utility analyses and understand patients' quality of life. We have introduced six questions to illuminate the complex issues underlying utility measurement and acknowledge the challenges encountered in conducting such research. Although not strict guidelines, the six questions provide a structured approach for recognizing high-quality articles and a swift method for discarding low-quality articles. We recognize that many studies seem poor when judged by these criteria, including some of our own. Yet we encourage clinicians, who are otherwise busy, to be selective in identifying utility analysis that merit attention. Without a structured approach, the temptation is to dismiss all articles as worthless and read nothing. The listed criteria, we hope, will help readers appreciate the merits of utility analyses and the role of patients' quality of life in decision analysis.

Attitude to Health↗
PubMed1994

Screening for prostate cancer. A decision analytic view.

OBJECTIVE: To determine the clinical and economic effects of screening for prostate cancer with prostate-specific antigen (PSA), transrectal ultrasound (TRUS), and digital rectal examination (DRE). DESIGN: Decision analytic cost-utility analysis comparing four screening strategies with a strategy of not screening. We assumed that the cancer detection rate and stage distribution were predicted by each combination of tests and that localized cancer was treated with radical prostatectomy. For each strategy, we calculated life expectancy, quality-adjusted life expectancy (QALE), and cost-utility ratios for unselected and high-prevalence populations. DATA: Probabilities and rates for clinical events were gathered from published data. We assessed utilities by the time-trade-off method using urologists, radiation oncologists, and internists as subjects. The Clinical Cost Manager at the New England Medical Center provided cost data. RESULTS: In unselected men between the ages of 50 and 70 years, screening with PSA or TRUS prolonged unadjusted life expectancy but diminished QALE. Screening with DRE alone yielded no reduction in mortality at any age. All programs increased costs. Results were sensitive only to assumptions about the efficacy of treatment. In high-prevalence populations, screening produced a similar pattern: gains in unadjusted life expectancy, losses in QALE, and increased costs. CONCLUSIONS: Our analysis does not support using PSA, TRUS, or DRE to screen asymptomatic men for prostatic cancer. Screening may result in poorer health outcomes and will increase costs dramatically. Assessment of comorbidity, risk attitude, and valuation of sexual function may identify individuals who will benefit from screening, but selecting high-prevalence populations will not improve the benefit of screening.

Aged↗
PubMed1994

Effect of diagnostic testing for multiple sclerosis on patient health perceptions. Rochester-Toronto MRI Study Group.

BACKGROUND AND METHODS: We examined the effect on health perceptions of a diagnostic workup in 172 patients with suspected multiple sclerosis (MS) using two questionnaires (Mishel, Rand Medical Outcome Study) and three visual analogue scales measuring distress. Patients were categorized into "MS," "not MS," or "still uncertain" groups. RESULTS: Patients with a definitive diagnosis reported a significant decrease in uncertainty (analysis of variance [ANOVA] P = .0004). The Medical Outcome Study showed a slightly worsened perceived current health status (ANOVA P = .02) and future health outlook (ANOVA P = .001) in the MS group compared with the other two groups. Distress over physical symptoms decreased in all three groups and anxiety was more likely to decrease than increase even in those with MS. Prognostic uncertainty distress decreased in the not MS group and still uncertain groups, whereas it remained unchanged in the MS group (P = .9156). CONCLUSION: Significant and generally beneficial changes in patient health perceptions are seen associated with a neurologic workup in suspected MS, irrespective of the final diagnosis.

Adolescent↗
PubMed1994

A randomized trial of test result sequencing in patients with suspected multiple sclerosis. Rochester-Toronto MRI Study Group.

BACKGROUND AND METHODS: We performed a randomized trial of the incremental impact of high-volume contrast computed tomographic scan of the brain plus trimodal evoked potentials vs magnetic resonance imaging of the brain on neurologists' diagnostic labeling of patients with suspected multiple sclerosis (MS). Two hundred and four patients with suspected MS (clinically possible 59% or probable 41%-McAlpine criteria) were assessed by two neurologists. Patients were diagnostically categorized after reviewing the results of the tests presented in random order. RESULTS: Most of the change in diagnostic categorization occurred after presenting the first test result irrespective of result sequence (chi 2 = 0.01, P = .99). The diagnoses became more definitive when all test results were available (P < .001). Magnetic resonance imaging and evoked potential were suggestive of MS equally frequently (chi 2 = 0.57, P = .45). CONCLUSION: In suspected MS, there is no difference in diagnostic effect between brain magnetic resonance image scanning and computed tomography plus trimodal evoked potentials.

Adolescent↗
PubMed1994

A randomized crossover trial of Quick Medical Reference (QMR) as a teaching tool for medical interns.

OBJECTIVE: To determine whether the addition of Quick Medical Reference (QMR) to usual educational tools improves an intern's performance in managing clinical cases that test diagnostic and investigative skills. DESIGN: Randomized, controlled, single-blinded crossover study. SETTING: Tertiary care teaching hospital. SUBJECTS: Comprehensive medical interns who are proficient in the use of QMR. INTERVENTION: A total of 16 interns trained in the use of QMR were randomized to work up a total of six diagnostically challenging cases, three using medical textbooks plus access to QMR and three using textbooks and no access to QMR. MEASUREMENTS: The interns provided their solutions to the cases, which consisted of the differential diagnosis and investigations. They were scored by comparing their answers with the consensus answers provided by subspecialty consultants. For each intern, the difference in mean total scores with and without QMR was calculated. RESULTS: The mean difference in total scores was 7.2% benefit (p < 0.05, 95% CI = 0.05 to 14.4) using QMR. The beneficial difference was driven mainly by improvement in diagnostic scores, with the mean difference being 11.6% (p = 0.01, 95% CI = 2.4 to 20.8). Regression analysis showed that the more difficult the case, the greater the benefit of QMR. CONCLUSIONS: Quick Medical Reference may be a useful adjunct to interns in formulating diagnostic strategies for difficult clinical cases. However, since optimal conditions were chosen for QMR benefit in this study design, the small benefit in test scores must be weighed against the time required to teach QMR to interns.

Adult↗
PubMed1994

Using cost-effectiveness analysis for formulary decision making: from theory into practice.

The growth of expenditures on healthcare and pharmaceutical products is a concern to third-party payers because of the absence of market discipline (price signals that consumers face). Cost-effectiveness analysis is a method that allows third-party payers to systematically make judgements about the 'value for money' of these products. It moves beyond simple unit price comparisons of alternate interventions/products to consider the full stream of relevant cost and benefits. As formulary committees begin to adopt the systematic use of cost-effectiveness analyses to inform the debate, the exercise will move from an academic to a more practical application. This transition will require several important changes including defining the purpose of cost-effectiveness analysis, measurement of outcomes and data, format of reports, and contractual arrangements between the pharmaceutical industry and analysts. As more 'real world' experience is gained in the practical application of cost-effectiveness analysis, the quality of data will improve as will its value as an aid to decision making.

Cost-Benefit Analysis↗
PubMed1994

Meta-analysis of highly selective vagotomy versus truncal vagotomy and pyloroplasty in the surgical treatment of uncomplicated duodenal ulcer.

OBJECTIVE: To compare critically by meta-analysis the postoperative outcomes after truncal vagotomy and pyloroplasty (TVP) and after highly selective vagotomy (HSV). DATA SOURCES: A search was conducted on MEDLINE with the keywords "peptic ulcer" and "vagotomy". Bibliographics of the articles retrieved and review articles pertaining to the subject were scanned further. STUDY SELECTION: Included were only published prospective, randomized controlled trials comparing TVP and HSV in the English-language literature up to April 1991. Twelve studies were found. DATA EXTRACTION: Two authors, working independently, abstracted raw data on mortality, recurrence, dumping, diarrhea and postoperative Visick grading. DATA SYNTHESIS: A ratio greater than 1.0 indicates a higher proportion occurring with TVP and less than 1.0 a higher proportion with HSV. [Table: See Text] CONCLUSION: The results suggest that the likelihood of adverse long-term sequelae is higher with TVP whereas the likelihood of recurrence is higher with HSV.

Confidence Intervals↗
PubMed1993

Effect of alpha-interferon treatment in patients with hepatitis B e antigen-positive chronic hepatitis B. A meta-analysis.

PURPOSE: To determine whether alpha-interferon is effective in terminating viral replication and in eradicating the carrier state in patients with chronic hepatitis B virus (HBV) infection. DATA SOURCES: Randomized controlled studies published in the English literature between January 1966 and June 1992 were identified through a MEDLINE computer search. STUDY SELECTION: Fifteen randomized controlled studies with a total of 837 adult chronic HBV carriers who were positive for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) were identified. Studies were included if patients were treated for at least 3 months and followed for at least 6 months after cessation of therapy. RESULTS: Overall, the loss of HBsAg occurred 6% more often in interferon-treated patients than the natural seroconversion seen in controls (7.8% compared with 1.8%, P = 0.001), and the loss of viral replication occurred approximately 20% more often in treated patients than in controls (33% compared with 12% for loss of HBeAg and 37% compared with 17% for the loss of HBV DNA, P = 0.0001) if patients received interferon for 3 to 6 months and were followed for 6 to 12 months. Interferon also had a significant treatment effect on the development of antibodies to HBsAg (anti-HBs), antibodies to HBeAg (anti-HBe), and on the normalization of alanine aminotransferase levels. CONCLUSIONS: Alpha-interferon is effective in terminating viral replication and in eradicating the carrier state in patients with chronic HBV infection who are HBeAg positive when these patients are treated for 3 to 6 months and followed for 6 to 12 months after cessation of therapy. Follow-up studies are required to determine whether interferon reduces the risk for developing cirrhosis or hepatocellular carcinoma.

Adolescent↗
PubMed1993

Bronchoscopy versus empirical therapy in HIV-infected patients with presumptive Pneumocystis carinii pneumonia. A decision analysis.

The outcomes of alternative strategies for the management of pulmonary complications in patients infected with the human immunodeficiency virus (HIV) and with suspected Pneumocystis carinii pneumonia were compared using a decision analysis model. A decision tree was constructed using baseline probabilities derived from published data and expert opinion. The case scenario analyzed was that of a patient not currently receiving anti-Pneumocystis prophylaxis who presents with moderate pulmonary symptoms and fulfills the Centers for Disease Control (CDC) criteria for presumptive P. carinii pneumonia. Two strategies were compared: (1) early bronchoscopy with appropriate therapy based on the results, and (2) empiric treatment for P. carinii (trimethoprim/sulfamethoxazole or pentamidine, and steroids) with delayed bronchoscopy in those not responding to 5 days of empiric therapy. The expected 1-month survival rate (with and without quality of life adjustment) was found to be essentially the same for the two strategies using the baseline probabilities, and the decision remained a toss-up within the clinically relevant range of published probabilities for P. carinii pneumonia in patients fulfilling the CDC criteria. Because early bronchoscopy does not offer any additional survival benefits and is associated with greater costs and disutility, empiric therapy would appear to be the superior management strategy in this scenario.

AIDS-Related Opportunistic Infections↗
PubMed1993

Guidelines for economic analysis of pharmaceutical products: a draft document for Ontario and Canada.

In Canada, provincial formulary review committees consider the effectiveness, safety, and cost of products when they derive advice for each Minister of Health. This article offers a draft set of guidelines for pharmaceutical manufacturers making submissions which include economic information, moving beyond a simple presentation of the unit price of the pharmaceutical product (e.g. price per day or course of therapy) and comparison to similar prices for alternative products. A full economic analysis compares all relevant costs and clinical outcomes of the new product with alternate therapeutic strategies for treating patients with a particular condition. The perspective of the decision maker must be clearly identified. The quality of the evidence supporting estimates of the variables incorporated in the analysis should be evaluated. Sensitivity analyses are used to assess the robustness of the qualitative conclusions. Reviewers will examine the answers to a set of 19 questions. Manufacturers can use these questions as a worksheet for preparation of an economic analysis to be incorporated in a submission. These guidelines are intended to be a starting point for further refinement, and discussion with health economists in industry and academia. Considerable flexibility will be used in reviewing documentation supporting economic analysis. Those preparing submissions should be encouraged to experiment with various approaches as part of the general development of this field and to engage provincial review committees in ongoing discussions.

Canada↗
PubMed1992

Preoperative cardiac risk assessment for patients having peripheral vascular surgery.

PURPOSE: To review the methods used for preoperative cardiac risk stratification of patients having peripheral vascular surgery. DATA SOURCES: Relevant studies published before August 1991 were identified using a MEDLINE search of the English-language literature, followed by a manual search of the references of all identified articles. STUDY SELECTION: All clinical studies evaluating methods used for preoperative cardiac risk stratification of patients having peripheral vascular surgery. DATA EXTRACTION: The key data extracted from each article included the inclusion and exclusion criteria of the study patients, the techniques used for testing and the corresponding definitions of positive test results, and the clinical outcomes of the tested patients. Data were analyzed using a Bayesian conceptual framework, and pretest probabilities were converted to post-test probabilities using calculation of likelihood ratios. RESULTS: Patients with high scores on clinical cardiac risk indexes (Goldman index greater than 12 or Detsky index greater than 15), or more than three of the criteria identified by Eagle (age greater than 70 years, diabetes, angina, Q waves on electrocardiogram, or ventricular arrhythmias) are likely to be at higher risk for cardiac death and myocardial infarction after vascular surgery. Those with both low scores and none of Eagle's criteria may be at lower risk, but this result has not been reproduced by independent studies. Neither group of patients would benefit from further investigation for cardiac risk stratification. Patients with one or two of these criteria may be at intermediate risk and would benefit most from further testing for the purposes of risk stratification. Most of the published evidence shows that the absence of redistribution on dipyridamole-thallium scanning identifies a low risk for postoperative cardiac complications, whereas the presence of redistribution predicts a high risk. Preliminary reports suggest that preoperative monitoring for silent myocardial ischemia may also be useful in identifying a high-risk subset of patients. CONCLUSIONS: Patients identified clinically to be at either very low or high risk for cardiac complications after peripheral vascular surgery are unlikely to benefit from further risk stratification. Dipyridamole-thallium scanning is the test of choice for further evaluation of patients at intermediate clinical risk because studies have shown that it is sensitive enough to rule out a high-risk status for patients who do not have redistribution.

Bayes Theorem↗
PubMed1992

How attractive does a new technology have to be to warrant adoption and utilization? Tentative guidelines for using clinical and economic evaluations.

Because economic evaluations of health care services are being published with increasing frequency it is important to (a) evaluate them rigorously and (b) compare the net benefit of the application of one technology with that of others. Four "levels of evidence" that rate economic evaluations on the basis of their methodologic rigour are proposed. They are based on the quality of the methods used to estimate clinical effectiveness, quality of life and costs. With the use of the magnitude of the incremental net benefit of a technology, therapies can also be classified into five "grades of recommendation." A grade A technology is both more effective and cheaper than the existing one, whereas a grade E technology is less or equally effective and more costly. Those of grades B through D are more effective and more costly. A grade B technology costs less than $20,000 per quality-adjusted life-year (QALY), a grade C one $20,000 to $100,000/QALY and a grade D one more than $100,000/QALY. Many issues other than cost effectiveness, such as ethical and political considerations, affect the implementation of a new technology. However, it is hoped that these guidelines will provide a framework with which to interpret economic evaluations and to identify additional information that will be useful in making sound decisions on the adoption and utilization of health care services.

Canada↗
PubMed1992

Incorporating variations in the quality of individual randomized trials into meta-analysis.

Meta-analysis is a method of synthesizing evidence from multiple sources. It has been increasingly applied to combine results from randomized trials of therapeutic strategies. Unfortunately there is often variation in the quality of the trials that are included in meta-analyses, limiting the value of combining the results in an overview. This variation in quality can lead to both bias and reduction in precision of the estimate of the therapy's effectiveness. There are a number of methods for quantifying the quality of trials including the detailed Chalmers system and simple scales. The nature of the relationship between these quality scores and the true estimate of effectiveness is unknown at this time. We discuss four methods of incorporating quality into meta-analysis: threshold score as inclusion/exclusion criterion, use of quality score as a weight in statistical pooling, visual plot of effect size against quality score and sequential combination of trial results based on quality score. The last method permits an examination of the relation between quality and both bias and precision on the pooled estimates. We conclude that while it is possible to incorporate the effect of variation of quality of individual trials into overviews, this issue requires more study.

Bias↗