An-Najah Staff

Background—The aim of this study was to assess the relationship between the volume of cardiac transplantation procedures performed in a center and the outcome after cardiac transplantation.

Methods and Results—PubMed, Embase, and the Cochrane library were searched for articles on the volume–outcome relationship in cardiac transplantation. Ten studies were identified, and all adopted a different approach to data analysis and varied in adjustment for baseline characteristics. The number of patients in each study ranged from 798 to 14401, and observed 1-year mortality ranged from 12.6% to 34%. There was no association between the continuous variables of center volume and observed mortality. There was a weak association between the continuous variables of center volume and adjusted mortality up to 1 year and a stronger association at 5 years. When centers were grouped in volume categories, low-volume centers had the highest adjusted mortality, intermediate-volume centers had lower adjusted mortality, and high-volume centers had the lowest adjusted mortality but were not significantly better than intermediate-volume centers. Category limits were arbitrary and varied between studies

Conclusions—There is a relationship between center volume and mortality in heart transplantation. The existence of a minimum acceptable center volume or threshold is unproven. However, a level of 10 to 12 heart transplants per year corresponds to the upper limit of low-volume categories that may have relatively higher mortality. It is not known whether outcomes for patients treated in low-volume transplant centers would be improved by reorganizing centers to ensure volumes in excess of 10 to 12 heart transplants per year.

Three broiler trials were conducted to age of 7-days, 21-days and 42-days, for trials 2, 3, respectively and I. In trial 1, two treatments were used: 1) the control (c) in which chicks received no preventive medication in the form of chlortetracycline (tetracycline HCL); 2) preventive medication (m-7) in which one day old chicks were given a preventive course (for seven days) of chlortetracycline at 0.5 g/L drinking water. In trial 2, three treatments were used: treatments 1 (c) and 2 (m-7) where similar to those in trial 1; however, chicks in treatment 3 (m-10) were given the preventive course for 10 days. In the third trial, four treatments were used, 1) common broiler house clean-out and chicks were given no medication (c-nm); 2) common broiler house clean-out and one day-old chicks were given a preventive.