Background. In many healthcare contexts, evidence exists that patients who participate in research protocols (PRP) significantly differ from nonparticipants. These differences may affect the external validity of study findings, reflect access to care, and potentially explain sources of difference in patient outcomes. There is no comprehensive study evaluating PRP among transplant recipients.
Methods. We evaluated the national Scientific Registry of Transplant Recipients from 2000 to 2008 for liver, kidney, heart, lung, and simultaneous pancreas/kidney transplant recipients in the United States for which PRP for immunosuppressive medications is reported at follow-up. Our primary aims were to evaluate participant characteristics, compare outcomes between participants and nonparticipants, and assess variability of PRP between centers and medications.
Results. The national proportions of PRP at 1 year by organ were kidney (8.2%), liver (2.9%), heart (5.0%), lung (2.6%), and simultaneous pancreas/kidney (2.8%). Factors associated with PRP included recipients' educational attainment, insurance, race/ethnicity, gender and age, donor age, transplant number, income, distance to center, and center volume. Graft and patient survivals were significantly higher among PRP for kidney, liver, and lung transplant recipients. PRP varied markedly between centers (range, 0%–58%) and by immunosuppressant medications.
Conclusions. There are systematic differences between participants and nonparticipants in research in the transplant population that may affect the external validity of research findings. Superior outcomes among participants may suggest that participation in research itself affords certain benefits. Future research evaluating the mechanisms for differential participation rates and improved survival among participants is needed.
1 Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio.
2 Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio.
3 Department of Bioethics, Cleveland Clinic, Cleveland, Ohio.
4 Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, Ohio.
5 Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio.
6 Department of Cardiothoracic Surgery, Cleveland Clinic, Cleveland, Ohio.
7 Department of Hepato-Pancreato-Biliary, General Surgery and Transplant Surgery, Cleveland Clinic, Cleveland, Ohio.
This work was supported by a grant from the PhRMA Foundation.
The authors declare no conflict of interest.
The data reported here have been supplied by the Minneapolis Medical Research Foundation as the contractor for the Scientific Registry of Transplant Recipients (SRTR). The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy of or interpretation by the SRTR or the US Government.
8 Address correspondence to: Jesse D. Schold, Ph.D., Department of Quantitative Health Sciences, 9500 Euclid Avenue, JJN3-01, Cleveland Clinic, Cleveland, Ohio 44195.
J.D.S. participated in research design, writing of the manuscript, performance of research, and data analysis; L.D.B. and T.R.S. participated in research design, writing of the manuscript, and performance of research; D.A.G., S.M.F., D.M., J.F., B.R.S., and V.K. participated in writing of the manuscript and performance of research; and E.H. participated in writing of the manuscript, performance of research, and data analysis.
Received 10 January 2011. Revision requested 25 January 2011.
Accepted 8 March 2011.