Methodology and Credits

Website results are based on data contributed to the Collaborative Transplant Study by more than 400 kidney, heart, lung, liver and pancreas transplant centers from 42 countries. The CTS statistics are the result of the selfless efforts of several thousand physicians, surgeons, scientists, nurses, technicians, data managers, and other personnel working at the participating transplant centers. Each one of these individuals has contributed valuable information and deserves credit for having taken an active part in this project.

If you are working at a transplant center that is not participating in the CTS, please consider contributing to the CTS in the future. The strength of the CTS relies on recognition by workers in the field that these powerful statistics can only be generated if each one of us makes an active effort. For further information please contact us at

Baseline information is recorded in a standardized format shortly after transplantation. Centers with computer stored data can make electronic submissions from local, national, or international databases. All participants are informed of the study's emphasis on accuracy. Clinical follow up information is requested posttransplant at 3, 6 and 12 months, and yearly thereafter. All information reported by a center to the CTS is returned for verification. There are 4 mailing cycles a year in which clinical follow up information is requested. A center that fails to respond during 3 mailing cycles is inactivated from the study and can be reactivated only if the center's incomplete records are brought up to date. This policy ensures that the CTS statistics are based on a data set that is current, complete and as accurate as possible.

Patient and center confidentiality rules are strictly enforced. Each participating center must comply with its local ethical and consent guidelines and national data protection rules.

In addition to providing overall statistical analyses, the CTS conducts special projects in which the number of participants ranges from 15 to greater than 100 centers. Current projects include: DNA typing project, pre- and posttransplant antibody studies.

Graft and patient survival rates are computed according to the Kaplan-Meier method. If not stated otherwise, all failures (including patient death with a functioning graft) are included in the calculation of graft survival rates. For special situations, so-called "death-censored graft survival rates" are computed whereby patients dying with functioning grafts are censored.

see also: Information on citation policy


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