The use of linear models to investigate the "centre effect" on graft survival

First cadaver graft survival at 90 days in six UK centres was analysed, and found to differ widely between the centres (p less than 0.0005). Linear models were used to test whether these differences could be explained by other factors known to influence graft survival, such as age of recipients, tissue typing, blood group matching or year of graft. Adjusting for these factors singly and in various combinations did not reduce the significance of the "centre effect". These results held good both when deaths with a functioning graft within 90 days were treated as exclusions and also when they were treated as graft failures.