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Biomedical subjects

R M Poses

Publications and source records attributed to R M Poses.

52 records · Page 3Linked to original sources
PubMed1988

Severity of anaemia and operative mortality and morbidity.

In a case-control study of 125 surgical patients who declined blood transfusions for religious reasons operative mortality was inversely related to the preoperative haemoglobin level, rising from 7.1% for patients with levels above 10 g/dl to 61.5% for those with levels below 6 g/dl. Mortality rates were also related to blood loss during surgery, rising from 8% for patients who lost less than 500 ml to 42.9% for those who lost more than 2000 ml. Both preoperative haemoglobin level and operative blood loss should be considered in assessing the need for preoperative transfusion. In our study no patient with a haemoglobin level above 8 g/dl and operative blood loss below 500 ml died.

Analysis of Variance↗
PubMed1986

The comparative cost-effectiveness of statistical decision rules and experienced physicians in pharyngitis management.

We examined whether probability-based decisions for streptococcal pharyngitis, using probabilities derived from predictive models along with Tompkins' decision rules, could be more cost-effective than the actual decisions of ten physicians. We retrospectively calculated the probability of a positive throat culture ("disease") for each of 310 patients using four different models based on discriminant analysis (1), a branching algorithm (2), and logistic regression (3 and 4). "Projected decisions" were based on these probabilities and Tompkins' rules. We calculated direct medical and indirect costs per correct action taken (diseased patient-treated or nondiseased patient-not-treated). Two models' projected decisions were more cost-effective than the physicians'. Model 1 primarily would have reduced treatment costs (leaving no diseased patient untreated); model 4 primarily would have reduced throat culture costs (with 15% projected undertreatment). While using statistical decision rules may be cost-effective in this setting, their adoption should be consistent with physician and patient priorities.

Algorithms↗
PubMed1986

The importance of disease prevalence in transporting clinical prediction rules. The case of streptococcal pharyngitis.

Because clinical prediction rules often are applied in new settings to calculate the probability of a disease, we evaluated the accuracy of three rules for predicting streptococcal pharyngitis in 310 patients. Use of the rules led to overestimations of disease probability in 47%, 82%, and 93% of the patients. When we used receiver-operating characteristic curve analysis, no rule lost power to discriminate streptococcal from nonstreptococcal causes of pharyngitis. The overestimations in disease probability likely were caused by differences in disease prevalence between our setting (5%) and the settings in which they were developed (15% to 17%). All rules led to accurate predictions when they were adjusted for the disease prevalence found in our setting using a likelihood ratio formulation of Bayes' theorem. The value of prediction rules, like that of other diagnostic tests, is affected by differences in disease prevalence in different settings. Failure to recognize and adjust for these differences may cause poor decision making or the premature dismissal of valid rules.

Humans↗
PubMed1985

The accuracy of experienced physicians' probability estimates for patients with sore throats. Implications for decision making.

Ten physicians recorded their treatment decisions and estimated probabilities of streptococcal infection for patients with sore throats. Of 308 throat cultures, 15 (4.9%) were positive for group A streptococci. The physicians overestimated the probability of a positive culture for 81% of their patients and their estimates and treatment decisions were strongly associated. Of 104 patients treated before culture results were available, only eight had positive cultures. Probability overestimation may have been due to neglect of the low culture-positive rate, assignment of undue importance to weakly predictive or highly intercorrelated clinical features, and a value-induced bias, occurring when features important for treatment are erroneously linked to the likelihood of disease. Cognitive limitations in information processing may limit the effectiveness of pharyngitis management protocols that require subjective estimates of disease probability.

Adolescent↗
PubMed1984

Can physicians be rational about diagnostic tests?

Concerns about diagnostic test utilization have led to interest in the role of tests in clinical decision-making, and researchers have developed guidelines for interpreting the results of diagnostic tests using Bayesian probability revision and decision analysis. Although it acknowledges the importance of these quantitative models in medical education, this article identifies major obstacles that limit their application, demonstrating that " rational " decision-making may not be rational or optimal in clinical practice.

Clinical Laboratory Techniques↗
PubMedDate not supplied

A strategy to improve the utilization of pneumococcal vaccine.

OBJECTIVE: To evaluate the effectiveness of a computerized reminder for pneumococcal vaccination at hospital discharge and to determine patient and physician characteristics associated with increased use of the vaccine. DESIGN: Pre- and postintervention study. SETTING: All medical services in a university teaching hospital. PARTICIPANTS: All patients with at least one indication for pneumococcal vaccination discharged from the hospital during one of two three-month time periods; resident and faculty physicians caring for the same patients. INTERVENTIONS: Incorporation of a predischarge reminder for pneumococcal vaccination in the hospital information system. MEASUREMENTS AND MAIN RESULTS: Of 539 eligible patients discharged during the three months after the intervention, 244 (45%) received the vaccine compared with 16 of 474 (3.4%) before the intervention (p less than 0.0001). Following the intervention, patients discharged with a diagnosis of alcoholism were more likely to receive the vaccine than were those without that diagnosis (58.1% vs. 42.7%, p less than 0.05), while patients with a diagnosis of cancer were less likely to get the vaccine (42 of 130, or 32.3%) than were those without cancer (202 of 409, 49.3%) (p less than 0.01). Patients whose attending physicians specialized in hematology-oncology or cardiology were also less likely to receive the vaccine than were all other patients. With the intervention in place, physicians were more likely to vaccinate patients with more than one indication for pneumococcal vaccine. CONCLUSIONS: 1) A predischarge reminder is an inexpensive, effective method to improve physicians' utilization of pneumococcal vaccine in high-risk patients; 2) additional improvements in pneumococcal vaccine utilization will require selective components directed toward specific diagnoses or attending physician subspecialities.

Aged↗
PubMedDate not supplied

Physician detection of drinking problems in patients attending a general medicine practice.

OBJECTIVE: To assess the patient and physician characteristics that influence physicians' detection of problem drinking in their medical patients. SETTING: The outpatient medical clinic at an urban university teaching hospital staffed by interns and residents. DESIGN: Cross-sectional study of a randomly chosen subsample of consecutive patients. MEASUREMENT: Univariate and multivariate analysis with calculated adjusted odds ratios of factors associated with physician detection of drinking problems. A problem was diagnosed according to the patient's results on the alcohol module of the Diagnostic Interview Schedule (DIS). RESULTS: Physicians detected 22% of 189 presumably inactive problems and 49% of 92 current problems, i.e., those that have occurred within the preceding year. Multivariate correlates of detection of active problems included male patient gender, presence of gastrointestinal complications of excessive drinking, number of concurrent medical disorders, and previous medical record reference to alcohol (p less than 0.05). Physician gender and year of training were not associated with detection. CONCLUSION: Our physicians appear to rely on specific patient characteristics as well as the patient's medical record to detect drinking problems in their ambulatory patients. Their reliance upon these factors may hinder their detection of drinking problems in women patients and less seriously impaired individuals.

Alcoholism↗
PubMedDate not supplied

Evaluating physicians' probabilistic judgments.

Physicians increasingly are challenged to make probabilistic judgments quantitatively. Their ability to make such judgments may be directly linked to the quality of care they provide. Many methods are available to evaluate these judgments. Graphic means of assessment include the calibration curve, covariance graph, and receiver operating characteristic (ROC) curve. Statistical tools can measure the significance of departures from ideal calibration, and measure the area under ROC curve. Modeling the calibration curve using linear or logistic regression provides another method to assess probabilistic judgments, although these may be limited by failure of the data to meet the model's assumptions. Scoring rules provide indices of overall judgmental performance, although their reliability is difficult to gauge for small sample sizes. Decompositions of scoring rules separate judgmental performance into functional components. The authors provide preliminary guidelines for choosing methods for specific research in this area.

Decision Theory↗
PubMedDate not supplied

What difference do two days make? The inertia of physicians' sequential prognostic judgments for critically ill patients.

Medical authorities have asserted the importance of observing a patient's clinical course over time. Distinguished committees have suggested that changes over time in physicians' prognostic estimates should influence decisions to transfer patients out of intensive care units (ICUs). This study evaluated how the opportunity to observe patients over time affected physicians' prognostic estimates for a cohort of 269 critically ill patients sequentially admitted to a medical-surgical ICU in a teaching hospital. As soon as possible after admission and again 48 hours later, the authors obtained a quantitative estimate of the probability of survival through hospital discharge from each patient's house officer and primary attending physician, and the critical care attending physician on duty. They independently determined each patient's survival. From this population they analyzed 181 pairs of judgments made by the same house officers, 211 pairs by the same primary attendings, and 172 pairs by the same critical care attendings. The physicians' 48-hour estimates were little changed from their previous estimates for the same patients. The correlation coefficient for the house officers' paired estimates was 0.84 (p less than 0.0001); for the critical care attendings' estimates 0.84 (p less than 0.0001), and for the primary attendings' estimates, 0.90 (p less than 0.0001). Forty-eight hours did not substantially reduce the disagreements present between estimates made by different physicians for the same patient. No group of physicians substantially improved the reliability or the discriminating power of its later estimates. The physicians in the study could not take advantage of sequential clinical information over time. These results point out the need to teach physicians how to better integrate and process sequential clinical data.

Critical Care↗
PubMedDate not supplied

Availability, wishful thinking, and physicians' diagnostic judgments for patients with suspected bacteremia.

A prospective cohort study was done to assess the effects of value bias and the inappropriate use of the availability heuristic on physicians' judgments of the probability of bacteremia. Subjects of the study were 227 medical inpatients in a university hospital who had blood cultures done. Estimates of the probabilities that individual patients would have positive blood cultures were collected from the house officers who ordered the cultures. Clinical data and culture results were also obtained. Based on the data the authors calculated "value variables," reflecting doctors' assessments of the risks that individual patients would die in the hospital if they were to have bacteremia. "Recalled experience variables" reflected the doctors' recollections of recent experiences with patients with bacteremia. The physicians significantly overestimated the likelihood of bacteremia for most of their patients. Their ROC curve for this diagnosis showed moderate discriminating ability (area = 0.687, SE = 0.073). Two recalled experience variables were significantly associated with the physicians' probability estimates. The value variables were significantly inversely associated with them. These relationships were independent of several clinical variables and measures of disease severity. The physicians' intuitive diagnostic judgments were thus influenced by the availability heuristic and by wishful thinking, a form of the value bias. The availability heuristic may mislead physicians by causing them to believe that random variations in the prevalence of a nonepidemic disease represent real trends. Wishful thinking may lead physicians to underestimate the likelihood of a disease for patients most at risk for its consequences. Teaching physicians to develop better judgmental strategies may improve the quality of their judgments and hence their patient care.

Anti-Bacterial Agents↗
PubMedDate not supplied

Practice variation in the management of pharyngitis: the importance of variability in patients' clinical characteristics and in physicians' responses to them.

The objective of this study was to assess whether geographic differences in antibiotic-prescribing rates for patients with pharyngitis could be explained by intersite differences in patients' clinical characteristics and in how physicians responded to these clinical cues when making decisions. As part of the initial phase of a prospective controlled trial to improve physicians' diagnostic ability, the authors enrolled cohorts of consecutive patients seen at staff-model--HMO student health services in Pennsylvania and Nebraska. Physicians' decisions whether to prescribe antibiotics for 310 consecutive patients presenting with pharyngitis to the former and 214 such patients presenting to the latter at the time of the initial visit were examined. There was a large discrepancy between the antibiotic-prescribing rates at the student health services in Pennsylvania, 106/310, 32.4%, and Nebraska, 156/214, 72.9%. The clinical variables significantly independently associated with treatment at both sites in a logistic regression model were fever, adjusted odds ratio = 2.1 (95% CI = 1.1, 3.8); exudates, 5.4 (2.8, 10); palatine petechiae, 6.5 (1.5, 28); rhinorrhea, 0.46, (0.25, 0.85); and high risk of complications, 3.8 (1.04, 14). There was a significant interaction between site and anterior cervical adenopathy, 5.5 (1.6, 19); and a borderline interaction between site and rhinorrhea, 2.4 (0.89, 6.7). Site was not a significant independent predictor of treatment, 1.8 (0.45, 6.6.). Practice variation was related to geographic differences in patients' clinical characteristics and in how physicians responded to these factors when prescribing antibiotics. How physicians weight patients' clinical characteristics when making decisions may be an important element of their "practice styles."

Anti-Bacterial Agents↗
PubMedDate not supplied

You can lead a horse to water--improving physicians' knowledge of probabilities may not affect their decisions.

OBJECTIVES: To determine whether improving physicians' judgments of the probability of streptococcal pharyngitis for patients with sore throats would affect their use of antibiotics and affect the variation in such use. DESIGN: Post-hoc retrospective analysis of data previously collected as part of a controlled trial. SETTINGS: University student health services in Pennsylvania and Nebraska. PATIENTS: Sequential patients with pharyngitis seen before and after the time clinicians received either an experimental educational intervention designed to improve probabilistic diagnostic judgments (at the Pennsylvania site) or a control intervention, a standard lecture (at the Nebraska site). The clinician-subjects were the primary case physicians practicing at either site. MEASUREMENTS: Clinical variables prospectively recorded by the clinicians, probability assessments, and treatment decisions. RESULTS: At the experimental site, despite marked decreases in clinicians' overestimations of disease probability after the intervention, the proportion of patients prescribed antibiotics showed a trend toward increasing: 100/290 (34.5%) pre-intervention, 90/225 (40%) post-intervention. The intervention did not decrease practice variation between individual doctors. Univariable and multivariable analyses showed no major change in the relationships between clinical variables and treatment decisions after the intervention. At the control site there was no major change in probability judgments or treatment decisions after the intervention. CONCLUSIONS: Teaching physicians to make better judgments of disease probability may not alter their treatment decisions.

Anti-Bacterial Agents↗
PubMedDate not supplied

An international comparison of physicians' judgments of outcome rates of cardiac procedures and attitudes toward risk, uncertainty, justifiability, and regret.

OBJECTIVE: Compare U.K. and U.S. physicians' judgments of population probabilities of important outcomes of invasive cardiac procedures; and values held by them about risk, uncertainty, regret, and justifiability relevant to utilization of cardiac treatments. DESIGN: Cross-sectional study. SETTING: University hospital and VA medical center in the United States; two teaching hospitals in the United Kingdom. PARTICIPANTS: 171 housestaff and attendings at U.S. teaching hospitals; 51 physician trainees and consultants at U.K. hospitals. MEASURES: Judgments of probabilities of severe complications and deaths due to Swan-Ganz catheterization, cardiac catheterization, percutaneous transluminal coronary angioplasty (PTCA), and coronary artery bypass grafting (CABG); judgments of malpractice risks for case vignettes; Nightingale's risk-aversion instrument; Gerrity's reaction-to-uncertainty instrument; questions about need to justify decisions; responses to case vignettes regarding regret. RESULTS: The U.S. physicians judged rates of two bad outcomes of cardiac procedures (complications due to cardiac catheterization; death due to CABG) to be significantly higher (p < or = 0.01) than did the U.K. physicians (U.S. medians, 5 and 3.5, respectively; U.K. medians 3 and 2). The median ratio of (risk of malpractice suit I error of omission)/(risk of suit I error of commission) judged by U.K. physicians, 3, was significantly (p=0.0006) higher than that judged by U.S. physicians, 1.5. The U.K. physicians were less often risk-seeking in the context of possible losses than the U.S. physicians (odds ratio for practicing in the U.K. as a predictor of risk seeking 0.3, p=0.003). The U.K. physicians had significantly more discomfort with uncertainty than did the U.S. physicians, as reflected by higher scores on the stress scale (U.K. median 48, U.S. 42, p=0.0001) and the reluctance-to-disclose-uncertainty scale (U.K. 40, U.S. 37, p < 0.0001) of the Gerrity instrument. There was no clear international difference in perceived need to justify decisions, or in regret. CONCLUSIONS: The results were not clearly consistent with the uncertainty hypothesis that international practice variation is due to differences in judged rates of outcomes of therapy or with the imperfect-agency hypothesis that practice variation is due to differences in physicians' personal values. The causes and implications of practice variations remain unclear.

Angioplasty, Balloon, Coronary↗