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Biomedical subjects

J S Schwartz

Publications and source records attributed to J S Schwartz.

At least 19 recordsLinked to original sources
PubMed1992

Prevention of Lyme disease after tick bites. A cost-effectiveness analysis.

BACKGROUND: In areas of endemic disease, the probability of Lyme disease after a tick bite ranges from about 0.012 to 0.05. Early treatment with oral antibiotics prevents most complications of Lyme disease, but antibiotics are generally not prescribed until rash or other symptoms develop. METHODS: We used decision analysis to evaluate the outcomes, costs, and cost effectiveness of three alternative strategies to treat patients bitten by ixodes ticks in areas of endemic Lyme disease: empirically treat all patients with two weeks of doxycycline, treat only patients in whom erythema migrans develops, and treat only patients with erythema migrans or a positive serologic test for Lyme disease one month after exposure. RESULTS: Empirical treatment is the least expensive strategy and results in the fewest cases of Lyme disease and the fewest complications when the probability of Borrelia burgdorferi infection after a tick bite is 0.036 or higher. For probabilities of infection below 0.036, empirical therapy prevents most major complications, sequelae, and adverse events, but it incurs additional minor complications, especially as the probability of infection falls below 0.01. CONCLUSIONS: Empirical treatment of patients with tick bites is indicated when the probability of B. burgdorferi infection after a bite is 0.036 or higher, and this treatment may be preferred when the probability of infection ranges from 0.01 to 0.035. When the probability of infection after a tick bite is less than 0.01, empirical therapy is not warranted.

Animals↗
PubMed1992

Spectrum bias in the evaluation of diagnostic tests: lessons from the rapid dipstick test for urinary tract infection.

OBJECTIVE: To determine if the leukocyte esterase and bacterial nitrite rapid dipstick test for urinary tract infection (UTI) is susceptible to spectrum bias (when a diagnostic test has different sensitivities or specificities in patients with different clinical manifestations of the disease for which the test is intended). DESIGN: Cross-sectional study. PATIENTS: A total of 366 consecutive adult patients in whom clinicians performed urinalysis to diagnose or exclude UTI. SETTING: An urban emergency department and walk-in clinic. MEASUREMENTS: After the patient encounter, but before dipstick test or culture was done, clinicians recorded the signs and symptoms that were the basis for suspecting UTI and for performing a urinalysis and an estimate of the probability of UTI based on the clinical evaluation. For all patients who received urinalysis, dipstick tests and culture were done in the clinical microbiology laboratory by medical technologists blinded to clinical evaluation. Sensitivity for the dipstick was calculated using a positive result in either leukocyte esterase or bacterial nitrite, or both, as the criterion for a positive dipstick, and greater than 10(5) CFU/mL for a positive culture. RESULTS: In the 107 patients with a high (greater than 50%) prior probability of UTI, who had many characteristic UTI symptoms, the sensitivity of the test was excellent (0.92; 95% CI, 0.82 to 0.98). In the 259 patients with a low (less than or equal to 50%) prior probability of UTI, the sensitivity of the test was poor (0.56; CI, 0.03 to 0.79). CONCLUSIONS: The leukocyte esterase and bacterial nitrite dipstick test for UTI is susceptible to spectrum bias, which may be responsible for differences in the test's sensitivity reported in previous studies. As a more general principle, diagnostic tests may have different sensitivities or specificities in different parts of the clinical spectrum of the disease they purport to identify or exclude, but studies evaluating such tests rarely report sensitivity and specificity in subgroups defined by clinical symptoms. When diagnostic tests are evaluated, information about symptoms in the patients recruited for study should be included, and analyses should be done within appropriate clinical subgroups so that clinicians may decide if reported sensitivities and specificities are applicable to their patients.

Adolescent↗
PubMed1992

The clinical course of pulmonary embolism.

BACKGROUND: Pulmonary embolism is a potentially fatal disorder. Information about the outcome of clinically recognized pulmonary embolism is sparse, particularly given that new treatments for more seriously ill patients are now available. METHODS: We prospectively followed 399 patients with pulmonary embolism diagnosed by lung scanning and pulmonary angiography, who were enrolled in a multicenter diagnostic trial. We reviewed all hospitalizations, all new investigations of pulmonary embolism, and all deaths among the patients within one year of diagnosis. RESULTS: Of the 399 patients, 375 (94 percent) received treatment for pulmonary embolism, usually conventional anticoagulation. Only 10 patients (2.5 percent) died of pulmonary embolism; 9 of them had clinically suspected recurrent pulmonary embolism. Clinically apparent pulmonary embolism recurred in 33 patients (8.3 percent), of whom 45 percent died during follow-up. Ninety-five patients with pulmonary embolism (23.8 percent) died within one year. The conditions associated with these deaths were cancer (relative risk, 3.8; 95 percent confidence interval, 2.3 to 6.4), left-sided congestive heart failure (relative risk, 2.7; 95 percent confidence interval, 1.5 to 4.6), and chronic lung disease (relative risk, 2.2; 95 percent confidence interval, 1.2 to 4.0). The most frequent causes of death in patients with pulmonary embolism were cancer (in 34.7 percent), infection (22.1 percent), and cardiac disease (16.8 percent). CONCLUSIONS: When properly diagnosed and treated, clinically apparent pulmonary embolism was an uncommon cause of death, and it recurred in only a small minority of patients. Most deaths were due to underlying diseases. Patients with pulmonary embolism who had cancer, congestive heart failure, or chronic lung disease had a higher risk of dying within one year than did other patients with pulmonary embolism.

Adult↗
PubMed1992

Stroke complicating acute myocardial infarction. A meta-analysis of risk modification by anticoagulation and thrombolytic therapy.

BACKGROUND: The objective of this meta-analysis was to examine the impact of systemic anticoagulation and thrombolysis on the total incidence of stroke following myocardial infarction. Additionally, we sought to compare the relative risk of stroke with different thrombolytic agents. METHODS: A computerized and manual literature search for controlled clinical trials of anticoagulants and thrombolytic agents in myocardial infarction reporting on total strokes in treated and control patients was used. Pooling was performed by calculating the Mantel-Haenszel odds ratio and 95% confidence interval (CI). RESULTS: The Mantel-Haenszel pooled odds ratio for anticoagulation trials was 0.46 (95% CI, 0.30 to 0.64), suggesting a benefit of anticoagulant therapy. However, a statistically significant degree of variability (heterogeneity) was present among study results. The odds ratios for all thrombolytic trials, tissue plasminogen activator, and streptokinase trials, respectively, were 1.08 (95% CI, 0.87 to 1.35), 1.28 (95% CI, 0.76 to 2.17), and 1.02 (95% CI, 0.80 to 1.30), suggesting no overall excess of stroke with thrombolysis. The pooled odds ratio for three studies directly comparing streptokinase and tissue plasminogen activator was 0.73 (95% CI, 0.61 to 0.86), suggesting an excess of stroke for patients treated with tissue plasminogen activator in comparison with streptokinase-treated patients. CONCLUSIONS: The available data may support a role for anticoagulants in reducing the incidence of stroke after myocardial infarction, but the heterogeneity among the trials makes interpretation of this effect difficult. Although the available data do not indicate an increase in stroke with thrombolysis, a direct comparison of tissue plasminogen activator and streptokinase reveals an excess of strokes with tissue plasminogen activator.

Anticoagulants↗
PubMed1992

The role of age in susceptibility to pneumococcal infections.

Whether or not age by itself increases susceptibility to pneumococcal infections separate from the effects of chronic disease is controversial. To address this issue, data collected for a retrospective cohort study of pneumococcal infections among 63 middle-aged and older veterans and 126 uninfected controls were reanalysed. Univariate analysis suggested a linear increase in risk with increasing age for patients 50 years old and older (p = 0.03). Subjects over age 80 years seemed to be at particularly high risk when compared with patients under 50 (odds ratio = 4.3, p less than 0.03). The odds of pneumococcal infection increased by an estimated factor of 1.33 (95% confidence interval = 1.03, 1.71) for each 10-year increase in age. Controlling for other risk factors did not appreciably change the point estimate of the age effect, but statistical significance was lost. This result however suggests that age has an independent association with the risk of pneumococcal infections. The potential impact of this finding on public policy urges that the association of age with the risk of pneumococcal disease be re-examined in a study of sufficient sample size to resolve the issue.

Age Factors↗
PubMed1992

Hospital and patient characteristics associated with death after surgery. A study of adverse occurrence and failure to rescue.

We asked if the factors that predict overall mortality following two common surgical procedures are different from those that predict adverse occurrences (complications) during the hospitalization or death after an adverse occurrence, which we refer to as "failure to rescue." We examined 5,972 Medicare patients undergoing elective cholecystectomy or transurethral prostatectomy using three outcome measures: 1) the death rate (number of deaths/number of patients); 2) the adverse occurrence rate (number of patients who developed an adverse occurrence/number of patients); and 3) the failure rate (number of deaths in patients who developed an adverse occurrence/number of patients with an adverse occurrence). The death rate was associated with both hospital and patient characteristics. The adverse occurrence rate was associated primarily with patient characteristics. In contrast, failure to rescue was associated more with hospital characteristics, and was less influenced by patient admission severity of illness as measured by the MedisGroups score. We concluded that factors associated with hospital failure to rescue are different from factors associated with adverse occurrences or death. Understanding the reasons behind variation in mortality rates across hospitals should improve our ability to use mortality statistics to help hospitals upgrade the quality of care.

Age Factors↗
PubMed1992

Effect of alpha-adrenergic blockade with prazosin on large coronary diameter during exercise.

BACKGROUND: Exercise-induced dilation of coronary resistance vessels is limited by alpha-adrenergic mechanisms. However, the effect of alpha-adrenergic mechanisms on large coronary arteries during exercise is not known. METHODS AND RESULTS: In the present study, sonomicrometry was used to measure circumflex coronary arterial diameter during treadmill exercise before and after alpha 1-adrenergic blockade with prazosin in eight instrumented dogs. Before infusion of prazosin, exercise caused a fall in coronary vascular resistance (2.1 +/- 0.4 to 1.6 +/- 0.2 units, p less than 0.05) and dilation of the circumflex coronary artery (4.66 +/- 0.37 to 4.79 +/- 0.34 mm, p less than 0.05). Intracoronary infusion of prazosin during exercise caused a further decrease in coronary vascular resistance (1.6 +/- 0.2 to 1.4 +/- 0.2 units, p less than 0.05) and a further increase in circumflex coronary arterial diameter (4.79 +/- 0.34 to 4.83 +/- 0.34 mm, p less than 0.05). Intracoronary infusion of vehicle without prazosin during exercise did not cause a further decrease in coronary vascular resistance or increase in coronary diameter. Prazosin caused no significant increase in heart rate, aortic pressure, or coronary blood flow. Therefore, both small coronary resistance vessels and large epicardial coronary arteries dilated during exercise and dilated further after alpha-adrenergic blockade. CONCLUSIONS: This finding indicates that alpha 1-adrenergic activity during exercise limits dilation of both large and small coronary arteries.

Adrenergic alpha-Antagonists↗
PubMed1992

Clinical and cost-effectiveness of outpatient strategies for management of febrile infants.

Young infants with fever are at risk for serious bacterial infection, but no consensus exists on the optimal approach to diagnosis and treatment. Although the traditional recommendation is always to perform all sepsis tests, including lumbar puncture, and administer intravenous (IV) antibiotics until culture results are negative, recent studies suggest administering intramuscular (IM) ceftriaxone with outpatient follow-up or using laboratory and clinical data to exclude low-risk patients from hospitalization, further testing, and antibiotic treatment. A decision analysis model was used to evaluate six strategies for the diagnosis and treatment of infants aged 28 to 90 days with temperature greater than or equal to 38.0 degrees C. Data from the literature, data from a 1991 study of 503 febrile infants, and direct, short-term costs from the Children's Hospital of Philadelphia were used as model inputs. The model was run for a hypothetical cohort of 100,000 febrile infants who did not require admission for focal infection or for other reasons that clearly necessitated admission. The model included six strategies: (1) no intervention; (2) all sepsis tests (lumbar puncture, blood culture, urine culture, white blood cell count, and urinalysis) followed by hospitalization and IV antibiotics for all infants; (3) all sepsis tests followed by IM ceftriaxone and outpatient management for most infants; (4) blood and urine cultures with white blood cell count and urinalysis followed by either lumbar puncture and IV antibiotics for high-risk infants or outpatient management without antibiotics for low-risk infants; (5) white blood cell count and urinalysis followed by either lumbar puncture, blood and urine cultures, and IV antibiotics for high-risk infants or outpatient management without antibiotics for low risk infants; and (6) clinical judgment followed by either all sepsis tests and IV antibiotics for high-risk infants or outpatient management without antibiotics for low-risk infants. The two "all sepsis tests" strategies prevented the most cases of death or neurologic impairment, 78% (when IV antibiotics were used) and 76% (when IM ceftriaxone was used) of all potential cases. The most cost-effective strategy was to use all sepsis tests followed by IM ceftriaxone for all patients without meningitis, at an incremental cost of only $3900 per sequela prevented relative to no intervention. Strategies under which only those patients selected as high-risk by laboratory criteria received antibiotic treatment were less effective but incurred lower rates of antibiotic complications. Clinical judgment alone was the least clinically effective and the second least cost-effective strategy.(ABSTRACT TRUNCATED AT 400 WORDS)

Ambulatory Care↗
PubMed1992

Cost and quality effects of alternative treatments for persistent gastroesophageal reflux disease.

BACKGROUND: Gastroesophageal reflux disease is commonly encountered by general internists and gastroenterologists. METHODS: We used decision analysis to assess the clinical and economic effects of three treatments--phase 1 therapy alone or combined with omeprazole or ranitidine hydrochloride therapy--for patients with persistent, symptomatic grade 2 or higher gastroesophageal reflux disease. To the maximum extent possible, data were obtained from the published literature. We convened an expert consensus panel to estimate specific data points when they were unavailable or contradictory in the literature, including estimates of optimal and actual clinical practice patterns. A 7-month model was used to correspond to the time frame of available clinical trial data. The perspective of the analysis was that of the payer. The costs of medical care for various clinical outcomes were based on actual mean payments made by Independence Blue Cross of Philadelphia and Pennsylvania Blue Shield. RESULTS: Although the retail payments for daily omeprazole therapy are the highest among the three interventions tested, it produced both the lowest expected overall payments for medical care and the most effective strategy for treating symptoms during the 7-month model. Omeprazole therapy was consistently approximately $1800 less costly than ranitidine therapy and $2700 less costly than phase 1 therapy alone during the period examined, regardless of whether empiric or nonempiric treatment strategies were used. Even when payments for major complications (the most important cost variable) were reduced by 80%, omeprazole therapy resulted in payments 17% and 22% lower than those associated with ranitidine therapy and phase 1 therapy alone, respectively. Omeprazole also produced the most symptom-free months during the 7-month follow-up period. The clinical and economic outcomes of performing an initial diagnostic workup, compared with treating patients empirically, were equal. CONCLUSIONS: We conclude that omeprazole therapy is the preferred initial therapeutic approach for patients with persistent, symptomatic gastroesophageal reflux disease in whom phase 1 therapy fails. Assessment of long-term approaches must await the results of extended clinical studies.

Adult↗
PubMed1992

The utility of preoperative electrocardiograms in the ambulatory surgical patient.

To determine the utility of preoperative screening electrocardiograms (ECGs) among ambulatory surgery patients, we reviewed the charts of 751 consecutive adult patients who underwent ambulatory surgery. Data were collected on demographic characteristics, coexisting medical problems, American Society of Anesthesiologists physical status score, preoperative ECG results, adverse intraoperative cardiovascular events, and postoperative cardiovascular complications. In our study population of relatively healthy outpatients, preoperative ECGs were abnormal in 42.7% of patients. Age, increased physical status score, and male gender were associated with a greater incidence of abnormal preoperative ECGs. There were 12 adverse cardiovascular perioperative events among the 751 patients (1.6%), and the preoperative ECG may have been clinically useful in six of these 12 patients. Neither preoperative ECGs nor results of preoperative screening questionnaires were predictive of adverse cardiovascular perioperative events. These findings question the utility of preoperative ECGs in the ambulatory surgery setting, especially among younger, relatively healthy patients.

Adolescent↗
PubMed1991

Diagnosing pulmonary embolism: new facts and strategies.

PURPOSE: To provide a clinical approach to the diagnosis of pulmonary embolism. DATA IDENTIFICATION: An English-language literature search using MEDLINE (1982 to 1990) and bibliographic reviews of textbooks and review articles. STUDY SELECTION: In addition to several reviews, studies that evaluated the diagnostic technology of pulmonary embolism were selected. Preference was given to studies with a prospective design, particularly those done within the past decade. DATA EXTRACTION: Studies were assessed independently by three unblinded observers. Data were chosen to describe the efficacy of diagnostic technology on the basis of disease prevalence, sensitivity and specificity, and predictive value. RESULTS OF DATA ANALYSIS: A normal lung scan or pulmonary angiogram rules out the diagnosis of clinically important pulmonary embolism with at least 95% certainty. Lung scan interpretations indicating high or low probability have approximately a 15% error in diagnosing or ruling out pulmonary embolism. The accuracy of either scan result improves when the clinical suspicion of pulmonary embolism matches the lung scan result. Serial impedance plethysmography of the lower extremities may exclude thromboembolism with 95% certainty in patients without high-probability lung scan results or cardiopulmonary disease. CONCLUSIONS: The combination of clinical suspicion and the results of the lung scan and impedance plethysmography appear to offer acceptable diagnostic accuracy in evaluating many patients suspected of having pulmonary embolism. The usefulness of this approach for patients with cardiopulmonary disease is still unknown.

Decision Trees↗
PubMed1991

Internists' practices in health promotion and disease prevention. A survey.

OBJECTIVE: To estimate internists' use of disease prevention and health promotion activities, and to explore demographic, professional, behavioral, psychological, cognitive, and organizational factors associated with the use of such practices. DESIGN: Mail survey. SETTING AND SUBJECTS: A sample of 2610 members and fellows of the American College of Physicians (ACP) participated in the study. They engaged in patient care activities more than 20 hours per week and were stratified by gender and region. They lived in four geographic areas of the United States (Northeast, Southeast, Central, and West), comprising 21 ACP regions. MEASUREMENTS: A questionnaire requesting background information as well as information about personal health; record keeping; use of immunizations (pneumococcal, influenza, tetanus, hepatitis B); use of screening tests and procedures for detecting cancer (breast examination, Papanicolaou smear, stool occult blood test) and other diseases (electrocardiograms, cholesterol level tests, chest radiographs); and behavioral counseling to promote health (in the areas of smoking, exercise, and alcohol and seat belt use). MAIN RESULTS: Internists used effective preventive interventions less frequently and ineffective practices more frequently than experts recommend. Internists' use of health promotion and disease prevention activities is associated with habit, attitude, and a lack of adequate knowledge. Younger physician age, general internal medicine practice, and personal health promotion and disease prevention practices were strongly associated with more appropriate use of recommended practices (P less than 0.01). CONCLUSIONS: Internists' use of disease prevention and health promotion activities falls short of expert recommendations. Programs to improve the delivery of preventive services might be aimed at improving physicians' personal health practices, might be directed toward patients, and might include the development of effective systems to remind physicians.

Counseling↗
PubMed1991

The counseling practices of internists.

OBJECTIVES: To determine the counseling practices of a group of internists in the areas of smoking, exercise, and alcohol and seat belt use, and to determine the associations among physicians' personal health habits and their counseling practices. DESIGN: A random stratified sample of members and fellows of the American College of Physicians in 21 regions selected to represent all areas of the United States. Because of the relatively small proportion of women in this group, they were oversampled. SETTING: Physicians' practices. PARTICIPANTS: One thousand three hundred and forty-nine internists (members or fellows of the College) returned questionnaires, for a response rate of 75%; 52% defined themselves as general internists. INTERVENTIONS: A questionnaire was used to obtain information on internists' use of cigarettes, alcohol, and seat belts and their level of physical activity. Data were obtained on the indications used for counseling and the aggressiveness of counseling about each of these four habits. MEASUREMENTS AND MAIN RESULTS: Bivariate and logistic regression analyses were used to compare the tendencies of internist subgroups both in using various indications for counseling and in the thoroughness of counseling. Generalists were more likely than specialists to counsel at least once all patients who were at risk and to be more aggressive in counseling. Ninety percent of respondents counseled all of their patients who smoked, but 64.5% never discussed the use of seat belts. Only 3.8% of these internists currently smoked cigarettes, 11.3% drank alcohol daily, 38.7% were extremely or quite active, and 87.3% used seat belts all or most of the time. Among men internists, for every habit except alcohol use, personal health practices were substantially associated with counseling patients; for example, nonsmoking internists were more likely to counsel smokers, and very physically active internists were more likely to counsel about exercise. Among women internists, being very physically active was associated with counseling more patients about exercise and alcohol use. CONCLUSIONS: The low level of self-reported counseling among these internists suggests that further emphasis on training in these skills is needed. The association between personal and professional practices suggests that medical schools and housestaff training programs should support health promotion activities for future internists.

Adult↗
PubMed1991

Restenosis after coronary angioplasty: a multivariate statistical model to relate lesion and procedure variables to restenosis. The M-HEART Investigators.

The Multi-Hospital Eastern Atlantic Restenosis Trial group obtained follow-up angiography in 510 patients with 598 successfully dilated coronary lesions who were enrolled in a controlled trial of the effects of a single dose of 1 g of methylprednisolone on restenosis after coronary angioplasty. The overall restenosis rate was 39.6%. The strongest univariate relations to the restenosis rate were found for lesion location (saphenous vein graft, 68%; left anterior descending artery, 45%; left circumflex artery and right coronary artery, 32%; p = 0.002); lesion length (less than or equal to 4.6 mm, 33%; greater than 4.6 mm, 45%; p = 0.001); percent stenosis before angioplasty (less than or equal to 73%, 25%; greater than 73%, 43%; p = 0.005), percent stenosis after angioplasty (less than or equal to 21%, 33%; greater than 21%, 46%; p = 0.017) and arterial diameter (less than 2.9 mm, 44%; greater than or equal to 2.9 mm, 34%; p = 0.036). Two multivariate models to predict restenosis probability were developed with use of stepwise logistic regression. The preprocedural model, which included only variables whose values were known before angioplasty, entered lesion length, vein graft location, left anterior descending artery location, percent stenosis before angioplasty, eccentric lesion and arterial diameter. The postprocedural model, which also included variables whose values were known after angioplasty was performed, was similar to the preangioplasty model except that it also entered postangioplasty percent stenosis and "optimal" balloon sizing but did not enter eccentric lesion. These data indicate that the probability of restenosis after angioplasty is determined predominantly by the characteristics of the lesion being dilated. They are consistent with the known intimal proliferative mechanism of restenosis, offer a means of identifying lesions at unusually high or low risk of restenosis, and of predicting the likelihood that a particular lesion will restenose after angioplasty and provide a rationale for stratification by restenosis probability in the design of future studies of restenosis.

Angioplasty, Balloon, Coronary↗