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R Hammett

Publications and source records attributed to R Hammett.

3 recordsLinked to original sources
PubMed1999

Meta-analysis of antibiotic prophylaxis in endoscopic retrograde cholangiopancreatography (ERCP).

BACKGROUND AND STUDY AIMS: Considerable controversy exists regarding the role of antibiotic prophylaxis prior to endoscopic retrograde cholangiopancreatography (ERCP), in that various studies of antibiotic prophylaxis have reached conflicting conclusions. The aim of this meta-analysis is to synthesize the data in order to determine whether antibiotic prophylaxis reduces the rate of occurrence of bacteremia and/or the rate of sepsis/cholangitis among patients undergoing ERCP. PATIENTS AND METHODS: Clinical trials were selected via Medline and Pubmed using subject words and textwords "ERCP", "antibiotic" and "antibiotic prophylaxis". Summary estimates of the risk ratios for the outcomes of bacteremia and sepsis/cholangitis were calculated. RESULTS: After 49 abstracts had been reviewed, seven randomized placebo-controlled trials of antibiotic prophylaxis prior to ERCP were identified. Upon further review, two studies were excluded because patients received antibiotics before and after the ERCP. Four studies reported on the clinical outcome of bacteremia. Five studies reported on the clinical outcome of sepsis/cholangitis. The summary relative risk of the association between antibiotic prophylaxis and bacteremia was 0.39 (95% CI, 0.12-1.29). For sepsis/cholangitis the summary relative risk was 0.91 (95 % CI, 0.39-2.15). CONCLUSIONS: Antibiotic prophylaxis prior to ERCP may reduce the incidence of bacteremia but this has little clinical relevance. Prophylaxis does not substantially reduce the incidence of sepsis/cholangitis and thus the routine use of antibiotic prophylaxis cannot be recommended.

Antibiotic Prophylaxis↗
PubMed1990

Computerized tomography brain scan tumor volume determinations. Sensitivity as an objective criterion of response to therapy.

In an effort to define more precisely and objectively computerized tomography (CT) brain scan evidence of glioma patient response to treatment, planimetric measurements of serial CT images of enhancing tumor areas were made using a digitizing tablet interfaced to a microcomputer for computing three-dimensional tumor volumes. The ability of a single investigator to measure a "significant change" in tumor volume was determined from that investigator's coefficient of variation (COV) for triplicate volume measurements (a total of 1701) on 155 scans of 27 patients with malignant gliomas. Planimetric volume data were compared with geometric computation of volumes based upon the product of the maximum diameter of enhancing tumor and the perpendicular diameter for each image made simultaneously with each planimetric measurement. The planimetric method COV was less than that for geometric computation, and the former method was employed for analysis of response to therapy in these same patients. Overall, for a tumor volume change to be significant (COV plus 2 standard errors of the means), the percentage change was determined to be 20%. However, the smaller the tumor volume being measured, the greater was the percentage change required in order to be significant. Thus, minimal measurable changes (%) were separately defined for large (greater than 14 cc), medium (8 to 14 cc), and small (less than 8 cc) tumor volumes. Tumor volumes computed from baseline (prior to investigational therapy) and from subsequent serial CT scans were compared, with response defined as a significant change. Responses to therapy based on significant volume changes were compared in each instance to the conventional visual viewbox comparison ("Gestalt") of serial scans. In 28% of scan comparisons, planimetric technique sensitivity permitted determination of significant enlargement or reduction in tumor size, while Gestalt comparison suggested no change. The use of quantitative tumor volume analysis of planimetric determinations of changes in tumor size during investigational therapy appears to permit recognition of either progression or regression of tumor size earlier than by Gestalt comparison in one-fourth of instances.

Brain Neoplasms↗