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R M Poses

Publications and source records attributed to R M Poses.

At least 19 recordsLinked to original sources
PubMed1995

Controlling for confounding by indication for treatment. Are administrative data equivalent to clinical data?

There has been controversy about whether confounding by indication for treatment--that is, owing to physicians' conscious efforts to base treatment decisions on patients' pretreatment prognoses--makes nonrandomized, observational comparisons of treatments invalid. Some now believe evidence from studies of practice variation means that physicians' treatment decisions have little relationship to patients' prognostic clinical characteristics. They therefore believe that patients who receive different treatments should vary little in their baseline prognoses, and multivariable statistical methods should easily be able to adjust for any resultant confounding, even when analyses are restricted to administrative rather than clinical data. The objective of this study is to determine whether adjusting for variables found in administrative data sets produces the same results as does adjusting for clinical variables. Data were reanalyzed from a previously enrolled prospective sequential cohort of 227 hospitalized patients with suspected bacteremia who had blood cultures. The treatment under study was aminoglycoside therapy given empirically, that is, before blood culture results were known. The outcome of interest was death during hospitalization. Univariable analyses suggest that empiric aminoglycoside therapy had a positive association with mortality, by univarible logistic regression, odds ratio (OR = 3.1 (95% confidence interval = [1.6, 5.8]). Few administrative variables had univariable associations with aminoglycoside use or death. Multivariable analyses that controlled for them still suggest that aminoglycosides increased mortality; for example, in one model, adjusted OR = 3.2 (1.6, 6.5). Many clinical variables were strongly associated with aminoglycoside use or death. Analyses that controlled for them suggested that empiric aminoglycosides did not increase mortality; for example, in one model, adjusted OR = 1.2 (0.55, 2.7.) Results of adjustment for confounding using administrative data disagreed with the results of adjustment using clinical data. It is concluded that nonrandomized, observational outcome studies that fail to control for prognostic differences between patients receiving different treatments may not always be valid.

APACHE↗
PubMed1992

Controlled trial using computerized feedback to improve physicians' diagnostic judgments.

The goal of this study was to test an innovative method to improve physicians' diagnostic judgments by integrating the use of a computer program (employing cognitive feedback to teach a clinical rule that predicts the probability of streptococcal pharyngitis), a traditional lecture, and periodic disease-prevalence reports. In a controlled trial using pre- and postintervention measures involving 885 patients, the authors compared the effects of the integrated method on the diagnostic judgments of seven experienced physicians at a university health service (from 1982 to 1985) with the effects of the lecture alone on the judgments of seven experienced physicians at a different university health service (1986 to 1987). The integrated method significantly improved the quality of the physicians' judgments as measured by calibration curves and Brier scores, and increased the level of agreement between the physicians' judgments and those made by the clinical prediction rule. The lecture alone produced less improvement in the quality of the physicians' judgments, and decreased the level of agreement with the rule. The authors conclude that this method, based on cognitive psychology, is a promising educational tool.

Computer-Assisted Instruction↗
PubMed1991

Ego bias, reverse ego bias, and physicians' prognostic.

OBJECTIVE: To evaluate the effects of "ego bias" on physicians' prognostic judgments. Ego bias is defined as systematic overestimation of the prognosis of one's own patients compared with the expected outcome of a population of similar patients. DESIGN: A prospective study of an inception cohort of critically ill patients followed until death or discharge from the hospital. PATIENTS: Consecutive patients admitted to either an ICU or an intermediate ICU at a teaching hospital during January and February 1987, excluding patients admitted after coronary artery bypass grafting, for elective dialysis, or transferred to the intermediate ICU from another critical care unit. MAIN OUTCOME MEASURES AND COMPARISONS: House officers' and critical care attending physicians' assessments of the likelihood of inhospital survival for each patient, and their assessments of the overall survival rate of ICU and intermediate ICU patients were compared with each other and with actual survival rates. RESULTS: The attending physicians' predictions for individual patients were significantly lower than their judgments of the overall survival rate, 79.8% vs. 88.0%, p = .0067, suggesting the presence of a "reverse ego bias." The house officers' predictions for individual patients were significantly higher than their judgments of the overall survival rate, 73.5% vs. 68.9%, p = .018, suggesting the presence of ego bias. The magnitude and directions of these differences varied significantly among the attending physicians (F = 4.3, degrees of freedom = 3, p = .0062 by repeated-measures analysis of variance) and the house officers (F = 6.3, degrees of freedom = 5, p = .0001). CONCLUSIONS: The critical care attending physicians exhibited reverse ego bias that was mainly a function of their optimism about the overall survival rate for critically ill patients. The house officers exhibited ego bias that was mainly a function of their pessimism about the overall survival rate for critically ill patients.

Attitude of Health Personnel↗
PubMed1991

Does hypogonadism contribute to the occurrence of a minimal trauma hip fracture in elderly men?

The risk of MTHF in hypogonadal elderly men was investigated with a case-control model. Cases and controls were selected from males age 65 years and older residing in the 120-bed McGuire Veterans Affairs Medical Center Nursing Home Care Unit over a 5-day interval. Historical data and serum free testosterone (fTe) were available on 17 subjects with MTHF and 61 controls. When groups were compared for differences in age, race, alcohol abuse, cigarette abuse, and diseases or drugs that may be associated with MTHF, only race was significantly different. Although 25.6% of residents were black, 100% of MTHF subjects were white (P = 0.004). Hypogonadism was defined as a random fTe less than 9 pg/mL (normal 9 to 46 pg/mL) and was found in 21 subjects (26.9%). Of cases with a MTHF, 58.8% were hypogonadal compared with only 18.0% of controls. Utilizing logistic regression, a highly significant association was found between hypogonadism and MTHF (P = 0.008), and using the odds ratio, subjects with hypogonadism were 6.5 times more likely to have a MTHF (95% CI 2.0 to 20.6). To adjust for race, the odds ratio was repeated excluding black subjects, and the results remained highly significant (4.6, 95% CI 1.3 to 16.2). We conclude that hypogonadal elderly white men may be at increased risk for MTHF.

Black or African American↗
PubMed1990

Derivation and validation of a clinical diagnostic model for chlamydial cervical infection in university women.

We developed and prospectively tested a logistic regression model for chlamydial cervical infection. Study subjects included 2271 women receiving gynecologic care in our student health clinic. Clinical data were collected in a standardized fashion. We identified cell culture--isolated Chlamydia trachomatis from 133 (9%) of 1458 subjects in the derivation set and 73 (10%) of 729 subjects in the validation set. Model variables included a new sexual partner within 2 months or more than one sexual partner within 6 months; cervical ectopy; cervical friability; at least 20 polymorphonuclear leukocytes per high-power field in cervical secretions; white blood cells in vaginal secretions; and use of an antibiotic active against C trachomatis within a month. This model can distinguish women with low, medium, and high risks of chlamydial infection (on derivation set: receiver operating characteristic curve area, 0.710; SE, 0.026; on validation set: area, 0.698; SE, 0.035) using simple clinical information obtained in the office.

Adolescent↗
PubMed1990

Are two (inexperienced) heads better than one (experienced) head? Averaging house officers' prognostic judgments for critically ill patients.

Inexperienced physicians may make prognostic judgments and management decisions about acutely ill patients in the absence of supervision. We hypothesized that mathematically combining judgments of junior and senior house officers might yield aggregate judgments as good as those made by experienced critical care attending physicians. We obtained independent quantitative assessments of the likelihood of in-hospital survival for 269 sequential intensive care unit admissions from the patient's intern or resident and the critical care fellow and attending physician on duty within 24 hours of admission, and compared these judgements with mortality data. By logistic regression, the residents' and fellows' judgments added independent prognostic information to each other (likelihood ratio chi 2, 7.6; df = 1). The junior house officers' and fellows' assessments were significantly less reliable than the attending physicians' by calibration curves, and by Brier scores, 0.126 and 0.127 vs 0.119. All physicians had good discriminating ability (receiver operating characteristic areas [SE] were 0.83 [0.03], 0.85 [0.03], 0.86 [0.03], respectively). A simple average of the residents' and fellows' judgments was slightly but significantly more reliable by calibration curve and by Brier score, 0.117, and as discriminating (ROC area = 0.85, SE = 0.03) as the attending physicians' judgments. Nonmedical studies have shown that averaging independent judgments may compensate for people's tendency to make extreme estimates, and may take advantage of their complementary abilities. This first medical application of this technique suggests that this form of voting by secret ballot may prove useful for health care teams making other judgments and decisions.

Clinical Competence↗
PubMed1989

The answer to "What are my chances, doctor?" depends on whom is asked: prognostic disagreement and inaccuracy for critically ill patients.

Physicians often must make prognostic judgments for critically ill patients, but we know little about how well they can perform this task. We prospectively measured disagreements among different physicians' quantitative prognostic judgments for 269 sequential admissions to an ICU, and evaluated the accuracy and discriminating ability of judgments made by different types of physicians. Many (44.7%) patients provoked one or more disagreements of at least 20 percentage points among the three possible pairings of physicians. Many patients whom one physician thought were certain to survive did not inspire such certainty in another of their doctors. The critical care attendings thought the changes of survival were less than or equal to 80% for 23, and between 81% and 95% for another 46 of 85 patients whom the patients' own attendings thought were certain to survive. There were some differences in the accuracy of the different physicians' estimates. All doctors showed excellent overall discriminating ability, but discriminated less well for postoperative patients. Lack of consensus about how to judge prognosis for critically ill patients may make it difficult to decide whom to admit to ICUs. These results underscore the need for valid predictive models to aid in decision-making for critically ill patients.

Adult↗
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↗