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P Peduzzi

Publications and source records attributed to P Peduzzi.

9 recordsLinked to original sources
PubMed1992

Predictors of bacteremia and gram-negative bacteremia in patients with sepsis. The Veterans Affairs Systemic Sepsis Cooperative Study Group.

BACKGROUND: We analyzed data from the Department of Veterans Affairs trial of steroid therapy for systemic sepsis to identify predictors of bacteremia and gram-negative bacteremia. METHODS: Of the 2568 patients screened for entry in the trial, 465 met the following criteria: presence of four of seven clinical signs of sepsis; blood cultures at the time of screening; and complete data on nine clinical parameters. The multivariate logistic regression model was used to identify predictors of bacteremia and gram-negative bacteremia. Predicted probabilities of having these types of infections were calculated using the identified predictors. Patients were then classified into groups with and without bacteremia (and gram-negative bacteremia) based on the predicted probability. Misclassification error rates were calculated for each method of categorization by comparing the true with the predicted grouping of patients. RESULTS: Three factors were independently predictive of bacteremia and gram-negative bacteremia: elevated temperature, low systolic blood pressure, and low platelet count. Using these three factors, classification methods were identified that predicted blood infection better than chance, but misclassification was also high. For predicting bacteremia, the maximum predicted positive rate was 83%, with a specificity of nearly 100% and a sensitivity of only 5%. For predicting gram-negative bacteremia, the maximum predicted positive accuracy was 100%, with a specificity also of 100% and a sensitivity of almost 0%. CONCLUSIONS: Using simple clinical parameters, we could not predict either bacteremia or gram-negative bacteremia with sufficient accuracy to be clinically meaningful; however, our approach represents a step in the direction of forecasting the bacterial organism responsible for sepsis in advance of culture results.

Adrenal Cortex Hormones↗
PubMed1991

Termination of the Department of Veterans Affairs Cooperative Study of steroid therapy for systemic sepsis.

The Department of Veterans Affairs Cooperative Study Program conducted a randomized, double-masked trial of steroid therapy versus placebo therapy for patients with systemic sepsis from 1983 to 1986. Treatment was initiated as soon as sepsis was recognized and before results of cultures confirmed infection. The original hypothesis was to test the effect of therapy on short-term (14-day) mortality in patients with gram-negative bacteremia. Because therapy had to begin before culture results were available, all septic patients had to be enrolled. Consequently, the study was modified to evaluate therapy in all patients with sepsis, and by post-stratification in those with gram-negative bacteremia. Patient enrollment was planned to continue for 3.5 years to achieve a sample size of 276 patients. After 223 patients were randomized, 14-day mortalities were 22% in the placebo-treated group versus 21% in the steroid-treated group (p = 0.97). In contrast, for the 51 patients with gram-negative bacteremia, mortalities were 27% placebo-treated versus 7% steroid-treated (p = 0.11). The Data Monitoring Board recommended continuation of the trial to evaluate what appeared to be an emerging gram-negative trend, but the Cooperative Studies Evaluation Committee decided to end the trial 12 months early because of the lack of efficacy in all septic patients. The reasons for the proposed extension and for the termination of the trial are presented. The more general problem of evaluating a biologically important subgroup imbedded in a large clinical trial is also discussed.

Bacterial Infections↗
PubMed1991

Ten-year incidence of myocardial infarction and prognosis after infarction. Department of Veterans Affairs Cooperative Study of Coronary Artery Bypass Surgery.

BACKGROUND: The 10-year incidence of myocardial infarction (fatal and nonfatal) and the prognosis after infarction were evaluated in 686 patients with stable angina who were randomly assigned to medical or surgical treatment in the Veterans Administration Cooperative Study of Coronary Artery Bypass Surgery. METHODS AND RESULTS: Myocardial infarction was defined by either new Q wave findings or clinical symptoms compatible with myocardial infarction accompanied by serum enzyme elevations with or without electrocardiographic findings. Treatment comparisons were made according to original treatment assignment; 35% of the medical cohort had bypass surgery during the 10-year follow-up period. The overall cumulative infarction rate was somewhat higher in patients assigned to surgery (36%) than in medical patients (31%) (p = 0.13) due to perioperative infarctions (13%) and an accelerated infarction rate after the fifth year of follow-up (average, 2.4%/yr in the surgical group versus 1.4%/yr in the medical group). The 10-year cumulative incidence of death or myocardial infarction was also higher in surgical (54%) than in medical (49%) patients (p = 0.20). According to the Cox model, the estimated risk of death after infarction was 59% lower in surgical than in medical patients (p less than 0.0001). The reduction in postinfarction mortality with surgery was most striking in the first month after the event: 99% in the first month (p less than 0.0001) and 49% subsequently (p less than 0.0001). The estimated risk of death in the absence of infarction was nearly identical regardless of treatment (p = 0.75). Exclusion of perioperative infarctions did not alter the findings. CONCLUSIONS: Although surgery does not reduce the incidence of myocardial infarction overall, it does reduce the risk of mortality after infarction, particularly in the first 30 days after the event (fatal infarctions).

Angina Pectoris↗
PubMed1991

Intent-to-treat analysis and the problem of crossovers. An example from the Veterans Administration coronary bypass surgery study.

In randomized clinical trials of treatment for ischemic heart disease that compare medical with surgical treatment, many persons initially assigned to medical therapy eventually receive surgical intervention. For example, in the three major trials of bypass grafting for stable angina, crossover rates from medical to surgical therapy were approximately 25% at 5 years. For this reason, the classic intent-to-treat analyses have been criticized for their inability to evaluate the "true" effect of treatment. In this article we emphasize the concept of "initial treatment" as it applies to intent-to-treat analyses and examine four proposed alternative methods of analysis based on adherence with survival data from the Veterans Administration Cooperative Study to illustrate the concepts. The alternative methods include (1) censoring crossovers when treatment changes, (2) transferring crossovers from the original to the new treatment group when treatment changes, (3) excluding all crossovers from analysis, and (4) counting crossovers from the date of randomization in the treatment ultimately received group. We point out the biases attendant on analyses based on adherence and reaffirm the validity of intent-to-treat analysis.

Actuarial Analysis↗
PubMed1979

A computer program for life table regression analysis with time dependent covariates.

This paper presents a computer program for analyzing time-dependent covariables in survival studies by the life table regression model described by Holford [3]. Basically, life table regression incorporates the elements of regression and the life table into a single model. Regression parameters are estimated by the method of maximum likelihood using the Newton-Raphson iterative procedure. The program provides two methods for testing hypotheses concerning regression coefficients, namely the standard normal deviate test and a Wald statistic based on the first and second derivatives of the log likelihood. Residual plots are provided to assess the fit of the model to the data.

Actuarial Analysis↗
PubMedDate not supplied

An evaluation of central laboratories in three VA cooperative studies.

We compared central laboratory with local determinations of key clinical measurements in three VA Cooperative Studies. Electrocardiographic evidence of new myocardial infarction was assessed in the study of Aspirin Therapy and Unstable Angina, ejection fraction measurement in the Coronary Artery Bypass Surgery Trial and lesion size in the Angioplasty Compared with Medicine (ACME) Trial. The findings in the Aspirin Trial indicated that central coding of all serial electrocardiograms in 1266 patients to detect new acute myocardial infarction by computer algorithm was not cost-effective when compared with the local investigator's diagnosis on the basis of a central Electrocardiographic Committee as the reference standard. In the other two trials, the contribution of the central laboratories was important because the assessments of the local investigators generally underestimated the degree of abnormality in the Bypass Trial and overestimated it in the ACME Trial. The VA results have clearly demonstrated two cases in which the decision for central evaluation was prudent, but one case in which it was not cost-effective. These equivocal findings indicate the need to evaluate the contribution of central laboratories when used as an adjunct to local determinations. Such evaluations may provide guidelines for decision-making in the design of future trials.

Angioplasty, Balloon, Coronary↗