Barbara J. McNeil

On the Elicitation of Preferences for Alternative Therapies

We investigated how variations in the way information is presented to patients influence their choices between alternative therapies. Data were presented summarizing the results of surgery and radiation therapy for lung cancer to 238 ambulatory patients with different chronic medical conditions and to 491 graduate students and 424 physicians. We asked the subjects to imagine that they had lung cancer and to choose between the two therapies on the basis of both cumulative probabilities and life-expectancy data. Different groups of respondents received input data that differed only in whether or not the treatments were identified and whether the outcomes were framed in terms of the probability of living or the probability of dying. In all three populations, the attractiveness of surgery, relative to radiation therapy, was substantially greater when the treatments were identified rather than unidentified, when the information consisted of life expectancy rather than cumulative probability, and when the problem was framed in terms of the probability of living rather than in terms of the probability of dying. We suggest that an awareness of these effects among physicians and patients could help reduce bias and improve the quality of medical decision making.

Primer on certain elements of medical decision making.

The value of a diagnostic test lies in its ability to detect patients with disease (its sensitivity) and to exclude patients without disease (its specificity). For tests with binary outcomes, these measures are fixed. For tests with a continuous scale of values, various cutoff points can be selected to adjust the sensitivity and specificity of the test to conform with the physicians goals. Principles of statistical decision theory and information theory suggest technics for objectively determining these cutoff points, depending upon whether the physician is concerned with health costs, with financial costs, or with the information content of the test.

Validating recommendations for coronary angiography following acute myocardial infarction in the elderly: a matched analysis using propensity scores.

We determined whether adherence to recommendations for coronary angiography more than 12 h after symptom onset but prior to hospital discharge after acute myocardial infarction (AMI) resulted in better survival. Using propensity scores, we created a matched retrospective sample of 19,568 Medicare patients hospitalized with AMI during 1994-1995 in the United States. Twenty-nine percent, 36%, and 34% of patients were judged necessary, appropriate, or uncertain, respectively, for angiography while 60% of those judged necessary received the procedure during the hospitalization. The 3-year survival benefit was largest for patients rated necessary [mean survival difference (95% CI): 17.6% (15.1, 20.1)] and smallest for those rated uncertain [8.8% (6.8, 10.7)]. Angiography recommendations appear to select patients who are likely to benefit from the procedure and the consequent interventions. Because of the magnitude of the benefit and of the number of patients involved, steps should be taken to replicate these findings.

Statistical Approaches to the Analysis of Receiver Operating Characteristic (ROC) Curves

In this article we review published and some unpublished work in statistical analyses of ROC curves. We describe both single and joint indices and indicate the approaches that have been taken to consider between-reader variations and correlations, within-reader variations, and variations and correlations between cases. We then discuss in detail a single index, the TP ratio at a fixed FP ratio (designated TPFP), or the FP ratio at a fixed TP ratio (designated FPTP). We show how to calculate confidence limits around any point on the curve; we further show, using the conventional Dorfman and Alf program and the jackknifing technique, how to calculate these confidence limits for multiple curves derived from the same sample of patients.

Comparison of magnetic resonance imaging and ultrasonography in staging early prostate cancer: Results of a multi-institutional cooperative trial

Abstract Background. In 1987, a cooperative study group consisting of five institutions was formed to determine the relative benefits of magnetic resonance imaging (MRI) and endorectal (transrectal) ultrasonography in evaluating patients with clinically localized prostate cancer (stage Ta or Tb). Methods. Over a period of 15 months, 230 patients were entered into the study and evaluated with identical imaging techniques. We compared imaging results with information obtained at the time of surgery and on pathological analysis. Results. MRI correctly staged 77 percent of cases of advanced disease and 57 percent of cases of localized disease; the corresponding figures for ultrasonography were 66 and 46 percent (P not significant). These figures did not vary significantly between readers; moreover, simultaneous interpretation of MRI and ultrasound scans did not improve accuracy. In terms of detecting and localizing lesions, MRI identified only 60 percent of all malignant tumors measuring more than 5 mm on pat...

Knowledge and Practices of Generalist and Specialist Physicians Regarding Drug Therapy for Acute Myocardial Infarction

BACKGROUND The respective roles of generalist and specialist physicians in the care of patients is currently a matter of debate. Information is limited about the knowledge and practices of generalist and specialist physicians regarding conditions that both groups treat, such as myocardial infarction. METHODS We therefore surveyed 1211 cardiologists, internists, and family practitioners in the states of New York and Texas about four treatments demonstrated by randomized clinical trials to be associated with improved survival after myocardial infarction (thrombolytic therapy, immediate and long-term use of aspirin, and long-term use of beta-blockers) and two treatments for which such evidence is lacking (diltiazem for patients with pulmonary congestion and prophylactic lidocaine). We asked physicians about the effect of each treatment on survival and the likelihood that they would prescribe each class of drugs. RESULTS For the four beneficial treatments, the cardiologists believed more strongly than the internists and family physicians that survival was improved by the treatment, and they were more likely to prescribe these drugs (P < 0.001). For example, 94.1 percent of cardiologists said they were very likely to prescribe thrombolytic agents to treat an acute myocardial infarction, as compared with 82.0 percent of internists and 77.3 percent of family practitioners. Conversely, for the two treatments for which trials showed no evidence of a survival benefit, cardiologists were less likely than internists and family practitioners to think there was such a benefit and less likely to prescribe the drugs (P < 0.001). For example, 4.7 percent of cardiologists reported that they were very likely to use prophylactic lidocaine, as compared with 13.1 percent of internists, and 16.5 percent of family practitioners. When we used logistic regression to adjust for potential confounders, all the differences between the cardiologists and the internists and family practitioners remained significant (P < 0.02). CONCLUSIONS Internists and family practitioners are less aware of or less certain about key advances in the treatment of myocardial infarction than are cardiologists. This finding underscores the need to improve the dissemination of information from clinical trials to generalist physicians, particularly if they are to have an enlarged role in the evolving health care system.

Use and Misuse of the Term “Cost Effective” in Medicine

There has been mounting pressure on the medical profession in recent years to stem the rise in national health care expenditures. One result of that pressure has been the popularization of the term...

Use of cardiac procedures and outcomes in elderly patients with myocardial infarction in the United States and Canada

BACKGROUND Acute myocardial infarction is a leading cause of morbidity and mortality in the United States and Canada. We performed a population-based study to compare the use of cardiac procedures and outcomes after acute myocardial infarction in elderly patients in the two countries. METHODS We compared the use of invasive cardiac procedures and the mortality rates among 224,258 elderly Medicare beneficiaries in the United States and 9444 elderly patients in Ontario, Canada, each of whom had a new acute myocardial infarction in 1991. RESULTS The U.S. patients were significantly more likely than the Canadian patients to undergo coronary angiography (34.9 percent vs. 6.7 percent, P< 0.001), percutaneous transluminal coronary angioplasty (11.7 percent vs. 1.5 percent, P<0.001), and coronary-artery bypass surgery (10.6 percent vs. 1.4 percent, P<0.001) during the first 30 days after the index infarction. These differences in the use of cardiac procedures narrowed but persisted through 180 days of follow-up. The 30-day mortality rates were slightly but significantly lower for the U.S. patients than for the Canadian patients (21.4 percent vs. 22.3 percent, P=0.03). However, the one-year mortality rates were virtually identical (34.3 percent in the United States vs. 34.4 percent in Ontario, P= 0.94). CONCLUSIONS Short-term mortality after an acute myocardial infarction was slightly lower in the United States than in Ontario, but these differences did not persist through one year of follow-up. The strikingly higher rates of use of cardiac procedures in the United States, as compared with Canada, do not appear to result in better long-term survival rates for elderly U.S. patients with acute myocardial infarction.

Auranofin therapy and quality of life in patients with rheumatoid arthritis. Results of a multicenter trial

In a six-month, randomized, double-blind study at 14 centers, auranofin (3 mg twice daily) was compared with placebo in the treatment of patients with classic or definite rheumatoid arthritis. All patients had unremitting disease for at least the previous six months and at least three months of therapy with nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs, oral steroids, and analgesics were allowed throughout the trial. Efficacy was analyzed in 154 patients who received auranofin and 149 who received placebo. To reflect an expanded view of outcome assessment, the measures used included some 20 nontraditional measures of functional performance, pain, global impression, and utility (worth or value) in addition to five standard clinical measures of rheumatoid synovitis (e.g., number of tender joints). The nontraditional measures were mainly in the form of structured questionnaires administered by trained interviewers. To minimize the statistical problem of multiple comparisons, most of the measures were grouped into four composites--clinical (standard measures), functional, global, and pain--and the treatment effect for each composite was tested at the 0.0125 level of significance. Auranofin was superior to placebo in the clinical (p = 0.003), functional (p = 0.001), and global (p = 0.007) composites and trended similarly in the pain composite (p = 0.021). Individual measures within the composites consistently favored auranofin. Other measures, not part of the composites, also favored auranofin, including a patient utility measure designed for this study, the PUMS (p = 0.002). Results confirm the hypothesis that the favorable effect of auranofin on clinical synovitis is accompanied by improvements across a range of outcomes relevant to the patients quality of life.

Variation in the Use of Cardiac Procedures after Acute Myocardial Infarction

BACKGROUND There are large geographic differences in the frequency with which coronary angiography and revascularization are performed. We attempted to assess whether differences in case mix or in the treatment of specific groups of patients may explain this variability. We also assessed the consequences of various patterns of treatment. METHODS We studied patients covered by Medicare who were 65 to 79 years of age and were admitted to 478 hospitals with acute myocardial infarctions during 1990 in New York (1852 patients), where the rate of use of cardiac procedures is low, and in Texas (1837 patients), where the rate of use of such procedures is high. We compared the patterns of treatment of clinically similar groups of patients in the two states. We also compared mortality rates and measures of the health-related quality of life. RESULTS Coronary angiography was performed more often in Texas than in New York (45 percent vs. 30 percent, P < 0.001). The frequency of use in Texas was significantly higher than that in New York for all the clinical subgroups of patients analyzed except those at greatest risk for reinfarction. Over a two-year period, the adjusted likelihood of death was lower in New York than in Texas (hazard ratio, 0.87; 95 percent confidence interval, 0.78 to 0.98). Patients from Texas were 41 percent more likely to report angina (P = 0.002) and 62 percent more likely to say they could not perform activities requiring energy expenditure of 5 or more metabolic equivalents than patients from New York approximately two years after infarction (P < 0.001). CONCLUSIONS Physicians in Texas were more likely to perform angiography than physicians in New York for patients whose conditions allowed more discretion in the use of cardiac procedures. On average, there appears to be no advantage with respect to mortality or health-related quality of life to performing the procedures at the higher rate used in Texas.