P J Beitler | PubMed Health

PubMed1985

A mixed-effects model for categorical data.

A mixed model for categorical data from unbalanced designs which is directly analogous to a two-way ANOVA model for quantitative data is proposed. An extension of the fitting constants method is developed to estimate model variance components based on appropriate reductions in sums of squares. The resulting variance component estimators are incorporated into the covariance structure of a general linear models Wald statistic to test for treatment differences. These procedures are illustrated with data obtained from a multicenter clinical trial in which the treatments are regarded as fixed effects and the clinics are regarded as random effects.

Analysis of Variance↗

PubMedDate not supplied

A study of blood utilization in association with hysterectomy.

We performed a retrospective study of 167 women undergoing hysterectomy in a large tertiary-care teaching hospital in order to assess intraoperative blood requirements and to study the decision-making process that occurs when blood is transfused intraoperatively. Recommended preoperative blood orders for hysterectomy patients based on data from the study are provided. Although "type and screen" is commonly considered to be an adequate preoperative order for patients undergoing vaginal hysterectomy, our data indicate that 2 units may be a more appropriate order when the procedure is combined with pelvic floor repair. The preoperative hematocrit, the estimated intraoperative blood loss, and the duration of the hysterectomy were integral to the decision-making process. If women undergoing hysterectomy were transfused intraoperatively only when their hematocrit actually fell to 30 percent, and not in anticipation of such an event, unnecessary transfusions would be reduced.

Adult↗