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B Littenberg

Publications and source records attributed to B Littenberg.

At least 55 records · Page 3Linked to original sources
PubMed1995

A survey of current problems in meta-analysis. Discussion from the Agency for Health Care Policy and Research inter-PORT Work Group on Literature Review/Meta-Analysis.

The United States Agency for Health Care Policy and Research brought together representatives from each of the Patient Outcomes Research Teams (PORTs) as the Inter-PORT Meta-Analysis Work Group. The purpose of the meeting was to discuss a wide range of problems the panel had encountered in the area of meta-analysis. Several actual problems were presented, and tentative solutions to those problems were given. The PORTs had to consider issues such as quality assessment, survival analysis, rare events, sensitivity and specificity, and random effects models. The solutions presented represent the methods used by several researchers who are active in the area of meta-analysis.

Evaluation Studies as Topic↗
PubMed1994

Diagnosing pedal osteomyelitis: testing choices and their consequences.

OBJECTIVE: To compare the efficacies and cost-effectiveness of four strategies for the management of suspected pedal osteomyelitis in the setting of vascular impairment: 1) therapeutic trial of short-term antibiotics for presumed cellulitis without osteomyelitis (short); 2) technetium bone scanning followed by either short-term therapy if negative or either a biopsy or aggressive long-term intravenous therapy if positive (scan); 3) bone biopsy followed by long-term intravenous therapy if positive or short-term therapy if negative (biopsy); and 4) immediate long-term intravenous antibiotics for presumed osteomyelitis (long). DESIGN: Decision analysis and cost-effectiveness analysis with sensitivity analyses. The main outcomes states are amputation and the resource expenditures associated with bone scans, biopsies, and therapies. DATA SOURCES: The authors obtained estimates of test accuracy from literature review and summarized them using newly developed meta-analytic techniques. MAIN RESULTS: The optimal decision depends heavily on the estimated probability of osteomyelitis at presentation. At very low probabilities, the short-term strategy is preferred. When the probability of osteomyelitis is from 2% to 8%, the lowest amputation rate occurs when one does a diagnostic scan. From 8% to 50%, the best outcomes follow biopsy. At probabilities higher than 50%, the preferred strategy is long-term antibiotics. However, the differences in outcomes are quite small even when osteomyelitis is a virtual certainty. CONCLUSIONS: Over the whole range of prior probabilities, the short-term strategy is the least expensive. At very low probabilities, it dominates the other strategies. When the likelihood of osteomyelitis is higher (10-20%), scanning results in outcomes and cost-effectiveness ratios comparable to those of immediate biopsy and is less invasive. When the probability of osteomyelitis is 50%, biopsy is quite cost-effective compared with all the other strategies (cost-effectiveness ratio = $15,502 per amputation averted) and is preferred to the scan strategy. When the confidence that a patient has osteomyelitis is very high (> 90% probability), the improved outcomes associated with long-term antibiotics are achieved with little additional expense and with favorable cost-effectiveness ratios compared with those of the other strategies.

Anti-Bacterial Agents↗
PubMed1994

Cost-effectiveness of preoperative autologous donation in coronary artery bypass grafting.

Concern about the safety of the allogeneic blood supply has made preoperative autologous blood donation (PAD) routine before major noncardiac operations. However, the costs and benefits of PAD in elective coronary artery bypass grafting (CABG) are not well established. We used decision analysis to (1) calculate the cost-effectiveness of PAD in CABG, expressed as cost per year of life saved, and (2) compare the health benefits of reducing allogeneic transfusions with the potential risks of autologous blood donation by patients with coronary artery disease. A prospective study of 18 institutions provided data on transfusion practice and blood product costs in CABG. On average, PAD in CABG costs $508,000 to $909,000 per quality-adjusted year of life saved, depending on the number of units donated. Preoperative autologous blood donation is more cost-effective (as low as $518,000 per year of life saved) when targeted to younger patients undergoing CABG at centers with high transfusion rates. The cost-effectiveness of PAD is strongly dependent on estimates of posttransfusion hepatitis incidence, but less so on plausible estimates of the current risk of human immunodeficiency virus transmission. Although the actual risk of PAD is uncertain, even a small fatality risk (> 1 per 101,000 donations) associated with blood donation by patients awaiting CABG negates all life expectancy benefits of PAD. At current costs, PAD by patients awaiting CABG is not cost-effective, producing small health benefits at high societal cost. For the individual patient, the risk of donating blood before CABG may well outweigh the benefits associated with fewer allogeneic transfusions.

Blood Transfusion, Autologous↗
PubMed1994

Determinants of physician ordering of preoperative autologous donations.

Preoperative autologous donation (PAD) is frequently utilized to reduce infectious disease transmission risks, but it is an expensive form of hemotherapy that is not always closely matched with the needs of the patients. We compared the use of PAD in an academic medical center with patient needs and then investigated the efficacy of a simple intervention to promote targeting of PAD toward patients most likely to benefit from having PADs available. Over a 3-month period, surgeons whose patients received allogeneic components were asked to complete a questionnaire designed to identify reasons for not ordering PAD. PAD units were used in 14 (11%) of 124 cases, accounting for 6% of perioperative red cell use. The responses (46, 42% of the surveys sent) stated that PAD had not been ordered because of time constraints (39%), medical problems (26%), anemia (15%), and lack of expectation of blood use (24%). Chart review documented the presence of cited conditions in 88% of cases. Logistic and cost concerns were not evident. However, only 8% of the 176 PAD units collected in that period were transfused. Following dissemination of PAD ordering guidelines, this proportion rose to 52% without a reduction in the proportion of elective surgical cases utilizing autologous transfusion. This improvement in ordering practice was maintained over at least in 5-month period. Thus we were able to improve the efficiency of PAD application (reducing over-ordering) through a simple feedback to surgeons that assisted them in targeting PAD toward patients most likely to need transfusion.

Academic Medical Centers↗
PubMed1994

Outcomes after displaced fractures of the femoral neck. A meta-analysis of one hundred and six published reports.

Methods of meta-analysis, a technique for the combination of data from multiple sources, were applied to analyze 106 reports of the treatment of displaced fractures of the femoral neck. Two years or less after primary internal fixation of a displaced fracture of the femoral neck, a non-union had developed in 33 per cent of the patients and avascular necrosis, in 16 per cent. The rate of performance of a second operation within two years ranged from 20 to 36 per cent after internal fixation and from 6 to 18 per cent after hemiarthroplasty (relative risk, 2.6; 95 per cent confidence interval, 1.4 to 4.6). Conversion to an arthroplasty was the most common reoperation after internal fixation and accounted for about two-thirds of these procedures. The remaining one-third of the reoperations were for removal of the implant or revision of the internal fixation. For the patients who had had a hemiarthroplasty, the most common reoperations were conversion to a total hip replacement, removal or revision of the prosthesis, and débridement of the wound. Although we observed an increase in the rate of mortality at thirty days after primary hemiarthroplasty compared with that after primary internal fixation, the difference was not significant (p = 0.22) and did not persist beyond three months. The absolute difference in perioperative mortality between the two groups was small. An anterior operative approach for arthroplasty consistently was associated with a lower rate of mortality at two months than was a posterior approach. Some reports showed promising results after total hip replacement for displaced fractures of the femoral neck; however, randomized clinical trials are still needed to establish the value of this treatment.

Arthroplasty↗
PubMed1993

Combining independent studies of a diagnostic test into a summary ROC curve: data-analytic approaches and some additional considerations.

We consider how to combine several independent studies of the same diagnostic test, where each study reports an estimated false positive rate (FPR) and an estimated true positive rate (TPR). We propose constructing a summary receiver operating characteristic (ROC) curve by the following steps. (i) Convert each FPR to its logistic transform U and each TPR to its logistic transform V after increasing each observed frequency by adding 1/2. (ii) For each study calculate D = V - U, which is the log odds ratio of TPR and FPR, and S = V + U, an implied function of test threshold; then plot each study's point (Si, Di). (iii) Fit a robust-resistant regression line to these points (or an equally weighted least-squares regression line), with V - U as the dependent variable. (iv) Back-transform the line to ROC space. To avoid model-dependent extrapolation from irrelevant regions of ROC space we propose defining a priori a value of FPR so large that the test simply would not be used at that FPR, and a value of TPR so low that the test would not be used at that TPR. Then (a) only data points lying in the thus defined north-west rectangle of the unit square are used in the data analysis, and (b) the estimated summary ROC is depicted only within that subregion of the unit square. We illustrate the methods using simulated and real data sets, and we point to ways of comparing different tests and of taking into account the effects of covariates.

Carcinoma, Non-Small-Cell Lung↗
PubMed1993

A structured literature review of treatment for localized prostate cancer. Prostate Disease Patient Outcome Research Team.

OBJECTIVE: We performed a structured literature review to define the clinical course of localized prostate cancer, the effectiveness of radical surgery and radiation therapy, and treatment complications. ARTICLE SELECTION: We identified more than 1600 English-language, MEDLINE referenced articles for 1966 through 1991. All but 144 were excluded because they lacked primary data, involved fewer than 15 patients, or described neither the course of the disease nor treatment complications. DATA SYNTHESIS: In these 144 articles, persistent genitourinary complications were more common after radical surgery than after external-beam radiation. Radiation resulted in a higher incidence of bowel problems. The median annual risks for the development of distant metastases and cancer-related death were 2.6% and 1.0%, respectively. Because tumor grade was correlated with metastases (Spearman correlation r = .56) and cancer mortality (r = .31), controlling for grade was necessary before we could compare the effectiveness of treatments for these outcomes. However, stratification by grade of malignancy was available in only nine of the patient series describing metastatic rates and in seven describing cancer-related mortality. Furthermore, in the patient series that described prostate cancer-related metastatic rates, 48% neglected to identify patients unavailable for follow-up, 92% did not stratify patients by age, and only 48% stratified patients by the extent of disease at treatment. CONCLUSIONS: Although we were able to compare complications of treatments, we were unable to determine treatment effectiveness for localized prostate cancer because of methodologic inadequacies in the literature we reviewed. Until better scientific evidence is available, patients and their physicians cannot make informed choices based on knowledge of the benefits of radical prostatectomy, radiation, or watchful waiting.

Aged↗
PubMed1993

Should adult tetanus immunization be given as a single vaccination at age 65? A cost-effectiveness analysis.

OBJECTIVE: To compare three vaccination strategies for the prevention of adult tetanus. Each strategy includes childhood primary immunization and wound prophylaxis, and one of the following: 1) the currently recommended booster every ten years; 2) a single booster at 65 years of age; or 3) no intervention after age 6 except for wound prophylaxis. METHODS: Cost-effectiveness analysis was used to compare the three different strategies. A Markov model, cycled annually from age 5 through age 85, was applied to each strategy to predict the incidence and costs of tetanus for the U.S. adult population. RESULTS: The three strategies have very similar effects on life expectancy but different costs. Expressed incremental to no intervention after childhood primary immunization, the decennial booster strategy is least cost-effective, with a discounted incremental cost-effectiveness ratio of $143,138 per year of life saved compared with $4,527 for the single-booster strategy. Sensitivity analysis demonstrates that the decennial strategy is more effective but more costly over a wide range of model assumptions. CONCLUSIONS: The current policy of recommending tetanus booster vaccinations every ten years is effective but much more costly than a more easily implemented policy that also provides considerable protection against tetanus. The authors recommend forsaking decennial boosters in favor of a policy of including a single booster at age 65 along with other recommended health maintenance maneuvers reserved for that age.

Adolescent↗
PubMed1993

The cost-effectiveness of preoperative autologous blood donation for total hip and knee replacement.

Although the frequency of preoperative autologous blood donation is increasing dramatically, the economic implications of its use remain largely unexplored. Decision analysis was used to calculate the cost-effectiveness of autologous blood donation for hip and knee replacement. Cost-effectiveness, expressed as cost per quality-adjusted year of life saved, was based on observed red cell use in 629 patients undergoing surgery at two tertiary-care centers. Autologous blood donation for bilateral and revision joint replacement cost $40,000 per quality-adjusted year of life saved at Center 1 and $241,000 at Center 2. Autologous blood donation for primary unilateral hip replacement cost $373,000 per quality-adjusted year of life saved at Center 1 and $740,000 at Center 2. Autologous blood donation was least cost-effective for primary unilateral knee replacement ($1,147,000/quality-adjusted year of life saved at Center 1 and $1,467,000/year at Center 2). Differences between autologous blood collections and transfusion requirements explained variations among procedures in the cost-effectiveness of autologous blood donation. Higher transfusion rates in autologous blood donors than in nondonors accounted for the poorer cost-effectiveness of autologous blood donation at Center 2 than at Center 1. Autologous blood donation is not as cost-effective as most accepted medical practices. Its cost-effectiveness can be improved substantially by the avoidance of overcollection and overtransfusion of autologous blood.

Blood Donors↗
PubMed1992

Management of small abdominal aortic aneurysms. Early surgery vs watchful waiting.

OBJECTIVE: To compare two clinical strategies for the management of small abdominal aortic aneurysms (AAAs) less than 5 cm in diameter: early surgery (repair small AAAs when diagnosed) and watchful waiting (measure AAA size every 6 months and repair when the diameter reaches 5 cm). DATA SOURCES: We reviewed data from an earlier longitudinal study of patients with small AAAs to estimate incidence rates of rupture or acute expansion. Estimates for other parameters in the model were obtained by searching the medical literature (MEDLINE, 1966 to present). DATA SYNTHESIS: We constructed a Markov decision tree to compare early surgery with watchful waiting in patients with asymptomatic AAAs less than 5 cm in diameter, with respect to long-term survival in quality-adjusted life years. The average annual rates of rupture or acute expansion for AAAs with a maximal transverse diameter of less than 4.0, 4.0 to 4.9, and at least 5.0 cm, are 0, 3.3, and 14.4 events per 100 patient-years of observation, respectively. At an average rupture rate of 3.3 events per 100 patient-years and an average operative risk for elective surgery (4.6%, 30-day mortality), our model predicts that early surgery improves survival in patients who present with a 4-cm AAA. The benefit of early surgery decreases with increased age at presentation. If the average rupture rate for AAAs less than 5 cm is assumed to be low (eg, 0.4 event per 100 patient-years), watchful waiting if favored, particularly as operative risk increases. The decision in this subgroup, however, is sensitive to possible future increases in operative risk. CONCLUSIONS: In the majority of scenarios that we examined, early surgery is preferred to watchful waiting for patients with AAAs less than 5 cm in diameter. Watchful waiting is generally favored, however, for patients with a low risk of AAA rupture or acute expansion, including those patients who present with very small AAAs (eg, < 4 cm). More accurate data concerning the rupture risk of AAAs less than 5 cm would improve clinical decision making.

Aortic Aneurysm, Abdominal↗
PubMed1992

Technology assessment in medicine.

The author defines the concepts medical technology and technology assessment and presents a paradigm for the evaluation of medical technologies. He proposes a hierarchical assessment scheme in which level I, biologic plausibility, compares the technology's proposed mode of action with current biologic information and theory. Level II, technical feasibility, determines whether the technology can be delivered to the target population. Level III, intermediate outcomes, assesses whether the technology has a short-term impact on the biologic or physiologic process that is diseased. Level IV, patient outcomes, investigates the overall medical, psychologic, and financial impacts of the technology upon the patient, including unintended side effects and long-term morbidity and mortality. Level V, societal outcomes, measures the cost of the technology to society in terms of resource use, ethical issues, and social and political hazards. As an example, the author employs this scheme to analyze the use of screening tests for hypercholesterolemia.

Biological Science Disciplines↗
PubMed1991

The diagnostic accuracy of rapid dipstick tests to predict urinary tract infection.

This study summarizes the diagnostic accuracy data for dipstick nitrite and/or leukocyte esterase tests (the index tests) as predictors of bacterial urinary tract infection as defined by quantitative culture (the reference test). On-line search of the literature using the MEDLARS database identified 1,017 citations, 51 of which were relevant and contained sufficient data for further analysis. From each citation, 2 x 2 tables of true-positive, true-negative, false-positive, and false-negative results were extracted. Four categories of index test were assessed: nitrite only, leukocyte esterase only, disjunctive pairing (dipstick positive if nitrite, leukocyte esterase, or both were positive), and conjunctive pairing (dipstick positive only if both nitrite and leukocyte esterase were positive). The true- and false-positive rates were calculated from each 2 x 2 table. Plots of true-positive rates versus false-positive rates demonstrated widely scattered points, indicating heterogeneity. A receiver-operating characteristic curve was fitted to the data using logistic transforms and weighted linear regression. This analysis revealed that the disjunctive pair is the most accurate index test. However, in many clinical settings, the posterior probability of urinary tract infection given a negative dipstick is too high to exclude it. Within most clinically relevant ranges of true- and false-positive rates, a negative urine dipstick test cannot exclude the diagnosis of urinary tract infection in patients with high prior probabilities of contracting this infection. For lower prior probabilities, the clinical efficacy of these rapid tests would best be determined by decision analysis, for which these receiver-operating characteristic functions would serve as valuable analytical tools.

Diagnostic Tests, Routine↗
PubMed1991

Outcome among surviving very low birthweight infants: a meta-analysis.

Because published outcome studies are the only available source of data about the morbidity among surviving very low birthweight infants (VLBW, less than 1500 g) a search was carried out of 1136 references in the English language. A total of 111 outcome studies were found that reported morbidity data in cohorts of VLBW infants born since 1960. The methods used and results obtained in these studies were systematically assessed. No agreement exists about the definition of study populations, descriptive statistics, or measurement of outcome. Follow up ranged from six months to 14 years. In 85 cohorts the incidence of cerebral palsy was recorded, and in 106 that of disability. Studies that followed up infants for longer time periods reported higher incidences of disability. Studies from the United States reported higher incidences of disability than those from other countries. The median incidence of cerebral palsy among all the cohorts studied was 7.7%, and the median incidence of disability was 25.0%. Despite substantial improvements in the mortality of VLBW infants, poor outcomes among survivors are common.

Cerebral Palsy↗
PubMed1991

U-titer: a utility assessment tool.

We have developed an automated, modular utility assessment software package called U-titer. The package implements the rating scale, category scaling, standard gamble, chronic and temporary time trade-off methods of assessing patient's preferences, and allows extensive tailoring of each method. In addition to calculating utilities, U-titer records information on the process experienced by the user. It can use information gathered in one module to coordinate another module. Our early experience suggests U-titer assessments are similar to traditional assessments. This software should facilitate both the study of patient's utilities and the study of the assessment methods and their implementation.

Attitude to Health↗