Biomedical subjects

B Littenberg

Publications and source records attributed to B Littenberg.

76 records · Page 5Linked to original sources

PubMedDate not supplied

Technetium bone scanning in the diagnosis of osteomyelitis: a meta-analysis of test performance. Diagnostic Technology Assessment Consortium.

PURPOSE: To determine the diagnostic performance of technetium bone scanning in the setting of possible osteomyelitis in the foot of a patient who has diabetes or other vasculopathy. DESIGN: Meta-analysis. Data identification and study selection: To be eligible for inclusion, a report must have used intravenous technetium-99m methylene diphosphonate or a similar agent in humans over the age of 16 years, must have addressed possible osteomyelitis of the lower extremity with ulcer or soft-tissue inflammation in the setting of diabetes, neuropathy, or vasculopathy, and must have allowed the generation of a two-by-two table. A structured search of the MEDLARS database found 296 possibly eligible reports; ten met all the inclusion criteria. DATA EXTRACTION AND SYNTHESIS: The reported sensitivity and specificity of each report were converted to their logistic transforms and a straight line was fitted by weighted least-squares regression. The line was then back-transformed to yield a summary receiver operating characteristic curve. The false-positive rate of the bone scan is at best in the range of 10 to 20%. This occurs at sensitivities between 70 and 80%. The studies with increased sensitivity also reported sizable increases in the false-positive rate ranging from 20 to over 90%. Even small increases in sensitivity have necessitated large sacrifices in specificity. Seven of the ten studies reported specificities under 70%. CONCLUSIONS: Published data defining the effectiveness of technetium bone scanning for the diagnosis of osteomyelitis in the impaired foot indicate relatively poor performance. In many clinical situations, the specificity of the bone scan will not be high enough to confirm the diagnosis of osteomyelitis.

False Positive Reactions↗

PubMedDate not supplied

A meta-analytic method for summarizing diagnostic test performances: receiver-operating-characteristic-summary point estimates.

The authors have devised a meta-analytic method to summarize diagnostic test performances, which they describe along with a clinical example wherein they analyze the performances of real-time ultrasonography in eight studies of the detection of proximal deep venous thrombosis of the lower extremity, selected on the basis of specific inclusion criteria. To evaluate the evidence for fitting a summary receiver operating characteristic (ROC) curve, a test of correlation between the estimates of true-positive rate (TPR) and false-positive rate (FPR) is performed. A high positive correlation argues for summarizing the studies with an ROC curve. In the absence of such correlation, a test of homogeneity is applied separately to the estimates of sensitivity (TPR) and specificity (TNR) to evaluate whether differences among studies are due to chance alone. If the estimates are homogeneous, a summary point estimate and confidence intervals (CIs) are calculated. As a final step, subgroup analyses can be performed to assess alternative explanations of variability in TPR and FPR. Within groups defined by the presence or absence of symptoms of venous thrombosis, a negative correlation between TPR and FPR and homogeneity among studies were found. For symptomatic patients, the summary TPR was 0.97 with a 95% CI of (0.94, 0.99) and the summary TNR was 0.97 (0.95, 0.99). For asymptomatic patients, the summary TPR was 0.66 (0.50, 0.81), and the summary TNR was 0.96 (0.90, 0.99). The difference in TPR between symptomatic and asymptomatic patients was statistically significant. There was no evidence that test referral bias or lack of independent interpretation of test results influenced these findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Confidence Intervals↗

PubMedDate not supplied

Estimating diagnostic accuracy from multiple conflicting reports: a new meta-analytic method.

Reports of diagnostic accuracy often differ. The authors present a method to summarize disparate reports that uses a logistic transformation and linear regression to produce a summary receiver operating characteristic curve. The curve is useful for summarizing a body of diagnostic accuracy literature, comparing technologies, detecting outliers, and finding the optimum operating point of the test. Examples from clinical chemistry and diagnostic radiology are provided. By extending the logic of meta-analysis to diagnostic testing, the method provides a new tool for technology assessment.

Data Interpretation, Statistical↗

PubMedDate not supplied

Evaluation of co-morbidity indices in patients admitted for chronic obstructive pulmonary disease.

BACKGROUND: There is limited and conflicting information on the use of co-morbidity instruments to predict mortality in patients with chronic obstructive pulmonary disease (COPD). METHODS: We sought to test the validity of the Charlson Index and another co-morbidity instrument, the Adult co-morbidity evaluation 27 (ACE-27), in patients admitted with COPD exacerbations. Co-morbidity scores were obtained by chart review. Information on mortality was retrieved from the Social Security Death Index. We examined the predictive validity of the Charlson and the ACE-27 using survival analysis. RESULTS: There were 112 patients eligible for the study. The ACE-27 but not the Charlson predicted survival, after adjusting for age, gender, and smoking history in Cox regression, hazard ratio (95% CI) of 1.99 (1.17-3.39). CONCLUSIONS: This study confirms earlier findings that the Charlson Index is not a reliable predictor of mortality in patients with COPD. However, the ACE-27 appears to be useful for predicting survival in this study.

Aged↗