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D A Asch

Publications and source records attributed to D A Asch.

82 records · Page 5Linked to original sources
PubMedDate not supplied

Knowing for the sake of knowing: the value of prognostic information.

In evaluating diagnostic tests, traditional methods in decision analysis often emphasize how the results of the test will or will not affect patient management. Clinicians are advised to avoid testing if the results will not alter treatment strategy or other management plans. But patients may be interested in the prognostic information that testing provides even if it is not used to guide treatment. The authors present a model that defines this prognostic information as the expected deviation from the prior probability of disease. The model generates utility functions that are curvilinear over prior probabilities. Whereas the traditional threshold approach to medical decision making produces at most three zones of management strategy (withhold, test, and treat), the incorporation of prognostic information into threshold analysis produces two additional zones (test but withhold anyway, and test but treat anyway). Conditions under which one or both of these additional zones will appear are described. The model justifies the practice of performing tests that cannot alter management plans; it explains the unwillingness of some patients to undergo diagnostic testing when they fear unwanted results; and it provides a method for quantifying the sensitive nature of confidential tests. The model is illustrated using the antibody test for the Smith antigen. This test has a high specificity but a low sensitivity for lupus erythematosus. Clinicians may use the test because a positive result will support their prior suspicion of disease even though they may not change their management strategy if the test result is negative. The advantage of testing in this setting lies in the test's potential for establishing with virtual certainty that the disease is present. Thus, the test is valued for the prognostic information it provides apart from its effect on patient management.

Decision Trees↗
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Omission bias and pertussis vaccination.

BACKGROUND: Several laboratory studies have suggested that many people favor potentially harmful omissions over less harmful acts. The authors studied the role of this omission bias in parents' decisions whether to vaccinate their children against pertussis. METHODS: Two hundred mail surveys were sent to subscribers to a magazine that had published articles favoring and opposing pertussis vaccination. Subjects were asked about their beliefs about the vaccine and the disease, and whether they had vaccinated their own children or planned to, and they were given test items to identify omission bias in their reasoning. RESULTS: One hundred and three subjects (52%) responded to the survey. Respondents who reported they did not or would not allow their children to be vaccinated (n = 43; 41%) were more likely to believe that vaccinating was more dangerous than not vaccinating (p < 0.001). They were also more likely to exhibit omission bias (p = 0.004), holding constant their stated beliefs about the danger of the vaccine. CONCLUSIONS: Omission bias plays a role in decisions not to vaccinate with pertussis vaccine, beyond the role played by belief about the risk of vaccination.

Adult↗
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Is the defensive use of diagnostic tests good for patients, or bad?

Physicians sometimes order diagnostic tests to reduce the risk of malpractice liability. The authors develop an expected-utility model that links a rational physician's concerns about malpractice liability to increases in the use of diagnostic tests and use this model to assess the effects of defensive testing on patients' interests. To do so, they adapt the threshold approach to clinical decision making to incorporate the physician's interests, focusing on 1) the effect of the physician's expected liability risks and 2) the effect of any expected liability reduction due to diagnostic testing. Surprisingly, the mere existence of liability risks is often sufficient to widen the range of disease probabilities for which diagnostic testing is the preferred clinical strategy. If testing reduces the physician's expected liability risks, the testing range is widened further. For some disease probabilities, testing is preferred by the physician even though it is not in the patient's best interests. When tests are performed in such instances, utility is transferred from the patient to the physician and the physician's insurer. Although the defensive use of diagnostic tests improves clinical outcomes for some patients, it worsens clinical outcomes for others. Moreover, defensive testing worsens the expected outcomes of all patients whose clinical strategies are changed. Physicians should realize that defensive testing necessarily reduces the overall quality of patient care.

Decision Making↗
PubMedDate not supplied

Public preferences for prevention versus cure: what if an ounce of prevention is worth only an ounce of cure?

BACKGROUND: The belief that small preventive efforts bring large benefits may explain why many people say they value prevention above all other types of health care. However, it often takes a great deal of preventive medicine to prevent a bad outcome. This study explores whether people value prevention or cure more when each brings the same magnitude of benefit and examines whether preferences for prevention or cure vary according to the severity of the disability of the patients who can receive the preventive or curative intervention. METHODS: 289 prospective jurors were presented with a policy dilemma involving how best to allocate funds to benefit people with varying levels of disability. Each project was said to influence the functional ability of 100 nursing home residents, either by improving their level of function or by preventing their level of function from declining. RESULTS: When given a choice between preventive and curative interventions, more subjects preferred the preventive intervention (37% vs 21%, p=0.002). However, when the strength of people's preferences was taken into account, the preference for preventive interventions was not statistically significant (p=0.135). With both preventive and curative interventions, the subjects preferred helping patients with more severe disabilities (p < 0.005 for both comparisons). This preference for helping more severely disabled patients did not differ for prevention and cure (p=0.663). CONCLUSION: When the magnitude of benefit was held constant, the subjects slightly preferred prevention over cure. In addition, they preferred directing limited resources toward those with greater disabilities, regardless of whether those resources were targeted toward prevention or cure. These findings suggest that previously stated preferences for prevention over cure may result from a belief that small efforts at prevention will be repaid by large reductions in the later need for cure.

Activities of Daily Living↗
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Carrier screening for cystic fibrosis: costs and clinical outcomes.

OBJECTIVES: To evaluate the costs and clinical effects of 16 alternative strategies for cystic fibrosis (CF) carrier screening in the reproductive setting; and to test the sensitivity of the results to assumptions about cost and detection rate, stakeholder perspective, DNA test specificity, chance of nonpaternity, and couples' reproductive plans. METHOD: Cost-effectiveness analysis. RESULTS: A sequential screening strategy had the lowest cost per CF birth avoided. In this strategy, the first partner was screened with a standard test that identifies 85% of carriers. The second partner was screened with an expanded test if the first partner's screen was positive. This strategy identified 75% of anticipated CF births at a cost of $367,000 each. This figure does not include the lifetime medical costs of caring for a patient with CF, and it assumes that couples who identify a pregnancy at risk will choose to have prenatal diagnosis and termination of affected pregnancies. The cost per CF birth identified is approximately half this figure when couples plan two children. CONCLUSIONS: The cost-effectiveness of CF carrier screening depends greatly on couples' reproductive plans. CF carrier screening is most cost-effective when it is performed sequentially, when the information is used for more than one pregnancy, and when the intention of the couple is to identify and terminate affected pregnancies. These conclusions are important for policy considerations regarding population-based screening for CF, and may also have important implications for screening for less common diseases.

Cost-Benefit Analysis↗
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Measuring community benefits provided by for-profit and nonprofit hospitals.

Nonprofit hospitals are expected to provide benefits to their community in return for being exempt from most taxes. In this paper we develop a new method of identifying activities that should qualify as community benefits and of determining a benchmark for the amount of community benefits a nonprofit hospital should be expected to provide. We then compare estimates of nonprofits' current level of community benefits with our benchmark and show that actual provision appears to fall short. Either nonprofit hospitals as a group ought to provide more community benefits, or they are performing activities that cannot be measured. In either case, better measurement and accounting of community benefits would improve public policy.

Benchmarking↗