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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
Am J Transplant. Author manuscript; available in PMC 2010 November 20.
Published in final edited form as:
PMCID: PMC2864790

Predictors of having a potential live donor: a prospective cohort study of kidney transplant candidates

Peter P. Reese, M.D., M.S.C.E., Judy A. Shea, Ph.D., Roy D. Bloom, M.D., Jeffrey S. Berns, M.D., Robert Grossman, M.D., Marshall Joffe, M.D., Ph.D., Ari Huverserian, and Harold I. Feldman, M.D., M.S.C.E.


The barriers to live donor transplantation are poorly understood. We performed a prospective cohort study of individuals undergoing renal transplant evaluation. Participants completed a questionnaire that assessed clinical characteristics as well as knowledge and beliefs about transplantation. A participant satisfied the primary outcome if anyone contacted the transplant center to be considered as a live donor for that participant. The final cohort comprised 203 transplant candidates, among whom 80 (39.4%) had a potential donor contact the center and 19 (9.4%) underwent live donor transplantation. In multivariable logistic regression, younger candidates (OR 1.65 per 10 fewer years, p<0.01) and those with annual income >=$15,000 (OR 4.22, p=0.03) were more likely to attract a potential live donor. Greater self-efficacy, a measure of the participant’s belief in his or her ability to attract a donor, was a predictor of having a potential live donor contact the center (OR 2.73 per point, p<0.01), while knowledge was not (p=0.56). The lack of association between knowledge and having a potential donor suggests that more intensive education of transplant candidates will not increase live donor transplantation. On the other hand, self-efficacy may be an important target in designing interventions to help candidates find live donors.

Keywords: live donor, kidney transplantation, health disparities


The ever-increasing waiting list for deceased donor kidney transplantation and the high mortality rate among individuals with end-stage renal disease (ESRD) have heightened the sense of urgency for transplant professionals eager to expand the pool of available organs.(1, 2) Compared to recipients of deceased donor kidneys, patients who undergo live donor kidney transplantation enjoy longer life and longer allograft survival, and are more likely to get a transplant prior to starting dialysis (35). Efforts to increase live donor transplantation, however, are hampered by poor understanding of the obstacles that individuals face in attracting a living donor.(3, 6, 7)

A number of studies have reported that women, older patients, and African-Americans with ESRD are less likely to be referred for transplant evaluation and also to receive a live donor kidney transplant.(819) Because most of these studies were either retrospective or cross-sectional, they provided limited information about how the knowledge, beliefs, social support or economic status of participants might have explained disparities in live donor transplantation. We previously reported the results of a study of renal transplant candidates. Surprisingly, women were more likely to have discussed donation with potential donors, and African-Americans were no less likely to have discussed donation with potential donors compared to transplant candidates of other races.(20) These findings suggested that barriers to live donor transplantation might change after patients come to the transplant center. We also measured self-efficacy, which is defined as a person’s belief that he or she is capable of accomplishing a particular goal – in this case, the ability of a renal transplant candidate to attract a potential donor.(21) We found that candidates with higher self-efficacy were more likely to report having talked to someone about becoming a donor.

The current study sought to identify transplant candidate characteristics that could be important targets for interventions to increase living donor transplantation. We hypothesized that transplant candidates with greater knowledge about the benefits of live donor transplantation and with greater self-efficacy related to finding a donor would be more successful in attracting potential live donors.

Materials and Methods

We conducted a prospective cohort study of adults with advanced kidney disease seen at the Hospital of the University of Pennsylvania Transplant Institute for initial medical evaluation for a kidney transplant between 12/13/2006 and 3/6/2008. Study enrollment occurred on 58 out of 120 total days during which these evaluations took place (the departure of a study coordinator and hiring of a new coordinator was the primary reason why enrollment did not occur on all days).

All patients attended a standard educational session that emphasized the benefits of both live and deceased donor transplantation. Afterwards, while waiting to meet with the transplant nephrologists, participants completed a questionnaire that was administered by trained research personnel. Clinical outcomes were subsequently assessed through review of the electronic medical record. The project was approved by the University of Pennsylvania Institutional Review Board.

Inclusion criteria

Adult patients coming for a transplant evaluation were eligible for participation, including those with a history of a failed allograft and those who had undergone a prior transplant evaluation at another institution.

Exclusion criteria

Unrelated to the study, the Transplant Program’s Multidisciplinary Kidney Transplant Patient Selection Committee determined all patients’ acceptability for renal transplantation. Patients not accepted as transplant candidates were excluded from the study. Patients who were wait-listed for multi-organ transplants other than kidney-pancreas transplantation were also ineligible because they were not considered candidates for live donor transplantation at this time. Patients who skipped more than 3 questions unrelated to demographics were also excluded. The center does not evaluate pregnant women, prisoners, or individuals less than 18 years of age.

Measurement of participant characteristics

The questionnaire included items that measured the following characteristics: 1) self-efficacy for attracting a potential live donor (3 items), 2) knowledge about clinical outcomes with live donor kidney transplantation (5 items), 3) concern about harming the donor (2 items), 4) willingness to ask for help in coping with kidney disease (4 items), and 5) social support (12 items). Original items were developed to measure self-efficacy, knowledge, concern, and willingness. For the social support domain, the questionnaire included the 12-item Multidimensional Scale of Perceived Social Support.(22, 23) Questionnaire development, including principal components analysis and reliability estimation, has been previously described in detail.(20) The domain questions are provided as appendix 1.

Appendix 1
Mean domain scores among participants with and without a potential live donor *

Participants also answered questions about demographic and clinical characteristics including ethnicity, gender, marriage or involvement with a significant other, income level, education, number of living siblings, number of living children, history of dialysis, prior renal transplant, and prior transplant evaluation. Age and cause of ESRD were abstracted from the electronic medical record.

Primary outcome: A potential live kidney donor contacts the transplant center

A participant was recorded as having experienced the primary outcome if any potential live donor for that participant contacted the transplant center to be evaluated. Participants were followed for a minimum of 6 months after study enrollment to determine whether they met the endpoint.

Secondary outcomes

Receipt of a live donor transplant and receipt of a deceased donor transplant were secondary outcomes.

Statistical analysis

Analyses were performed using STATA (Stata 10.0, Stata Corporation, College Station, TX). Means of continuous variables between two groups were compared using the t-test for normally distributed variables and the rank sum test for non-normal variables. Means of continuous variables among more than two groups were compared using ANOVA for normally distributed variables and the Kruskal-Wallis test for variables not normally distributed. Categorical attributes were compared between groups using chi-square. The ordinal variables of income and education were compared between groups using logistic regression.

A multivariable logistic regression model for the primary outcome was fit in which variables that were nominally associated in unadjusted analyses (p<0.15) were entered into the model.

Sample size

On the basis of preliminary data, we anticipated that 70 – 80% of individuals visiting the transplant clinic would meet eligibility criteria and that the ratio of candidates without a donor to those with a donor would be 2:1. We planned this study with the goal to be able to detect a 0.5 point difference on the 3-item Self-efficacy Domain or the 5-item Knowledge Domain between these groups, corresponding to half a standard deviation or half the value of a single question. A sample size of 144 was estimated to provide 80% power to detect this difference. Conservatively, we sought to enroll >190 transplant candidates.


Generation of the study cohort (Figure 1)

Figure 1
Generation of the final cohort

Three hundred ninety-one patients presented for an initial kidney transplant evaluation during the period of study enrollment, among whom 287 (73.4%) participated and returned the questionnaire. After eliminating ineligible individuals, 203 renal transplant candidates formed the final cohort.

Table 1 compares the age, gender, race, and cause of ESRD of 3 groups: patients in the final cohort, those who were undergoing testing or in meetings when the questionnaires were handed out, and those refused to participate or did not complete the questionnaire. Patients who refused to participate or complete the questionnaire were older (p=0.02) than patients in the other two groups.

Table 1
Demographic and clinical data of the final cohort, patients not approached, and patients refusing to complete questionnaire

The mean age was 50.8 years (range 18 – 76 years) among candidates in the final cohort. One hundred twenty-two (60.1%) were male. One hundred (49.3%) were white, 79 (38.9%) were African-American, and 11 (5.4%) were Hispanic. Sixty-two (30.5%) had been previously evaluated for a kidney transplant at a different institution. Consistent with clinical practice at our institution, all candidates were wait-listed for a deceased donor transplant whether or not a potential live donor was being considered.

Fewer than 5% of individuals had data missing for any variable except for income. Sixteen candidates (7.9%) did not indicate income level.

We assessed the primary outcome of having a potential live donor at a minimum of 6 months after study enrollment; the median time from enrollment to assessment was approximately one year (372 days).

Primary outcome

Eighty candidates (39.4%) had at least one potential live donor contact the transplant center. Among these candidates, the range of potential donors was 1 – 9, and the median was 1.

Comparison of domain scores between candidates with a potential donor and those without one (Table 2 and Appendix 1)

Table 2
Mean domain scores for transplant candidates who did and did not have any potential live donors

In unadjusted analyses, the only domain score that was higher among candidates with a potential donor was Self-efficacy (mean 2.2 versus 1.5 among candidates without a donor, p<0.01). The difference in Social Support did not achieve conventional levels of statistical significance (p=0.08), but met criteria for inclusion in multivariable regression. Contrary to our hypothesis, knowledge was not associated with having a donor (p=0.56).

Unadjusted analysis of demographic and clinical characteristics with the primary outcome of having a potential donor (Table 3)

Table 3
Unadjusted analysis of clinical, demographic and social characteristics with the outcome of having any potential live donors

Candidates with a potential donor were younger than candidates without a donor (mean age 47 years for those with a donor versus 53 years for those without a donor, p<0.01). An examination of candidate age by decade revealed that 71.4% of candidates under 30 years had a potential donor, whereas 46.7% of candidates ≥ 30 and < 40 years, 42.9% of candidates ≥ 40 and <50 years, 32.8% of candidates ≥ 50 and <60 years, 34.9% of candidates ≥ 60 and <70 years, and 11.1% of candidates ≥ 70 years had a potential donor.

Patients with a prior transplant evaluation at another medical center were less likely to have a donor (OR 0.52, CI 0.28 – 0.99, p=0.04), as were patients on dialysis (OR 0.43, CI 0.24 – 0.76, p<0.01).

Three other variables were not statistically significant, but met criteria for inclusion in multivariable analysis: white race versus other races (OR 1.59, CI 0.90 – 2.80, p=0.11), diabetes (OR 0.59, CI 0.32 – 1.09, p=0.09) and stratum of annual household income (OR 1.20, CI 0.96 – 1.49, p=0.11). Closer examination of the relationship of the 5 strata of income revealed that only 20% of patients in the lowest stratum (annual household income <$15,000) had a donor, whereas 39 – 46% of patients in the highest 4 strata had a potential donor. Because these small differences between the highest 4 strata did not appear to be clinically important, we collapsed income into a binary variable of either having income>=$15,000 or not.

Multivariable adjusted analysis of variables associated with having a potential donor (Table 4)

Table 4
Multivariable adjusted analysis of clinical, demographic and social characteristics with the outcome of having any live donors *

Self-efficacy score (OR 2.73 per additional point, CI 1.79 – 4.18, p<0.01), younger age (OR 1.65 per 10 fewer years, CI 1.20 – 2.26, p<0.01) and family income>=$15,000 (OR 4.22, CI 1.15 – 15.5, p=0.03) were associated with having a donor. The Hosmer-Lemeshow goodness of fit test for calibration of the model produced a p-value of 0.16.

Secondary outcomes

Nineteen patients (9.4%) received a live donor transplant and 20 patients (9.7%) received a deceased donor transplant.

Unadjusted analysis demonstrated that Self-efficacy (p<0.01) and Social Support Score (p=0.02) were associated with undergoing live donor transplantation.

Post-hoc analyses of relationships among candidate characteristics

In order to explore potential mechanisms responsible for the associations between age, income and the outcome of having a potential live donor, we examined whether the following factors were related: age and social support; age and diabetes; age and income>=$15,000; income>=$15,000 and social support.

Age was not significantly associated with social support (p=0.37), but was associated with having diabetes as the cause of ESRD (the mean age for diabetic ESRD candidates was 54.2 years versus 49.0 years for others, p<0.01).

Patients with income<$15,000 were younger than other patients (mean age 45 years versus 51 years for income>=$15,000, p=0.04). Patients with income<$15,000 also had less social support (mean score 64.6 versus 71.2 for income>=$15,000, p=0.03).

Reasons why potential donors did not proceed to donation (Table 5)

Table 5
Reasons why potential live donors did not proceed to donation*

A total of 121 potential kidney donors contacted the transplant center to be evaluated for the participants in the study. The major reasons why donation did not take place were: 1) donor did not follow up with required medical testing (38.0%); 2) donor had a medical contraindication such as hypertension (27.3%); and 3) donor was either blood type or crossmatch incompatible with the transplant candidate (19.0%).


Despite the numerous advantages of live donor transplantation, few candidates receive a live donor kidney transplant.(3) This study revealed that a candidate’s knowledge of the benefits of live donor transplantation did not predict the ability to attract a potential donor. The finding that older individuals and those with lower income were less likely to have a potential donor suggests that efforts to reduce disparities in access to transplantation should focus on these groups. The strong associations between self-efficacy and the outcomes of both having a potential donor and receiving a live donor transplant indicate that self-efficacy may be a logical target for intervention.

Our results related to knowledge have important implications for the design of programs to increase living kidney donation. The knowledge level of transplant candidates does not seem to be a crucial barrier to having a potential donor. This finding corroborates the results of our previous study in which knowledge was also not associated with having discussed donation with any potential donors.(20) We propose that the majority of candidates learn – through their physicians, coordinators or reading – that living donor transplantation has advantages. The problem in attracting a donor may instead lie in the unwillingness of candidates to ask potential donors to come forward, to make their renal disease known in their community, or the inability of candidates to motivate potential donors. We note that the National Institutes of Health recently announced a grant program to increase organ donation, with emphasis that interventions related to live donor transplant should aim to increase knowledge.(24) Our study suggests, however, that more intensive education of recipients will not increase donation; it is possible that educating the public or potential donors could accomplish this goal.

Our analysis demonstrated that older transplant candidates were much less likely to have a potential donor, which is consistent with prior studies.(9, 25) Older transplant candidates may feel protective of younger relatives and not encourage them to be evaluated. Older participants were also more likely to have ESRD caused by type II diabetes, a condition that could affect other family members and make them averse to donating.(26) The observation that older age is an obstacle to attracting a live donor merits attention in light of the recent Life Years from Transplant (LYFT) proposal by UNOS, which would change deceased donor allocation such that older patients will get lower priority for a kidney.(27) Our study showed that older age is a barrier to having a potential live donor and if this UNOS policy is accepted, older candidates will also face an obstacle to receiving a deceased donor transplant. Given the convincing evidence that transplantation prolongs survival for older ESRD patients, our results suggest that efforts to facilitate live donor transplantation should address age-related barriers.(2830)

Low income patients were also at a disadvantage in attracting a donor. We hypothesize that potential donors for these candidates in the lowest income stratum are also more likely to be poor and, therefore, less able to deal with the out-of-pocket expenses that medical evaluation requires.(31) Transplant candidates in the lowest income stratum also had lower social support, although this factor does not entirely explain the relationship between income and having a potential donor because our multivariable analysis adjusted for social support.

The lack of association between gender or race with the outcome of having a potential donor is important to consider in the context of evidence that female and black ESRD patients are less likely to receive live donor transplants.(8, 14, 25) Many women with ESRD who might benefit from transplantation are not referred for evaluation (8, 11, 18), but in our prior study of patients referred for transplantation, women were more likely to initiate conversations about donation with potential donors.(20) In the current study, the fact that gender was not related to having a donor suggests that the major obstacles to live donor transplantation for women exist prior to transplant referral, or after the donors begin medical testing (for instance, potential donors for women could be more likely to drop out of the evaluation process).

Similar explanations may account for the lack of association between black race and having a potential donor. Notably, Lunsford et al. reported that African-Americans were less likely to complete the donor evaluation.(7) The higher prevalence of chronic kidney disease (CKD) and risk factors for CKD such as hypertension among African-Americans might also make African-Americans less likely to be considered suitable for donation.(7, 32) Thus, African-American transplant candidates might be equally able to attract a potential donor, but less likely to receive a live donor transplant.

Our results related to self-efficacy may offer insight into the optimal design of programs to increase live donor transplantation. (21) Greater self-efficacy was a strong predictor that a potential donor would contact the center. It is possible that programs could be developed to increase self-efficacy about attracting or recruiting a potential donor. For instance, transplant candidates could be coached about how to talk to donors or how to “spread the word” about their need for a transplant to friends and family.(33).

Alternatively, self-efficacy may not be a useful target for intervention, and may instead act only as a predictor of the ability to attract a donor. However, even if self-efficacy is only a predictor, an intervention could still help candidates with low self-efficacy attract a donor. For instance, a clinical trial by Rodrigue et al. showed that a home-based counseling session about transplantation (which was usually attended by potential donors as well as candidates) increased the likelihood that a candidate would receive a live donor transplant.(34) This session did not require a high level of baseline candidate self-efficacy or knowledge to succeed. Other possible interventions – such as providing candidates with multimedia materials about transplant (such as DVD’s or brochures) to give to potential donors – could help candidates to attract donors even when self-efficacy was lacking.

We also acknowledge that patients who already had an interested donor prior to coming to transplant clinic might have had higher self-efficacy scores. If this explained the relationship between self-efficacy and having a donor contact the clinic, then self-efficacy might not be an important target for intervention. This possibility should be explored by measuring self-efficacy related to attracting a donor in future clinical trials that aim to increase live donor transplantation.

Our study has a number of strengths, but we acknowledge possible limitations related to generalizability and bias. Unlike many prior studies, ours had a prospective design enabling the measurement of diverse participant characteristics such as knowledge that could predict subsequent ability to attract a donor or undergo live donor transplantation.(9, 35, 36) With reference to generalizability, participants were recruited from a center that performs approximately 110 deceased donor and 60 live donor transplants per year, has a racially diverse population, and draws patients from urban and rural areas in the northeastern United States. It is uncertain whether transplant centers with different populations would find similar results. Additionally, patients refusing to participate in the study were older than participants; our results related to age and having a donor could be affected by the exclusion of these patients.

Our questionnaire could also have been subject to bias. For instance, patients with higher education or a prior transplant might have been more likely to answer the multiple choice questions about knowledge correctly. Our instrument, however, underwent extensive revisions and iterative testing to demonstrate its ability to measure the intended attributes.(20)


Given the superior clinical outcomes for recipients of live donor kidneys, facilitating living donor transplantation should be a high priority for transplant centers. Our study suggests the value of addressing obstacles to live donor transplantation faced, in particular, by older and low income patients. The lack of association between knowledge and having a potential donor indicates that education of transplant candidates alone is not likely to increase live donor transplantation. On the other hand, self-efficacy may be an important target in designing interventions to help candidates find live donors.


Funding Sources: Dr. Reese is supported by NIH Career Development Award, K23 - DK078688-01. Dr. Feldman is supported by NIH grant K24 - DK002651.


Disclosures: The authors have no financial interests to disclose.

Contributor Information

Peter P. Reese, University of Pennsylvania; Renal Division; 1 Founders, 3400 Spruce Street, Philadelphia, PA, 19104.

Judy A. Shea, University of Pennsylvania, Department of Medicine; Blockley 1232, 423 Guardian Drive, Philadelphia, PA 19104.

Roy D. Bloom, University of Pennsylvania; Renal Division; 1 Founders, 3400 Spruce Street, Philadelphia, PA, 19104.

Jeffrey S. Berns, University of Pennsylvania; Renal Division; 1 Founders, 3400 Spruce Street, Philadelphia, PA, 19104.

Robert Grossman, University of Pennsylvania; Renal Division; 1 Founders, 3400 Spruce Street, Philadelphia, PA, 19104.

Marshall Joffe, University of Pennsylvania, Department of Biostatistics; Blockley 602, 423 Guardian Drive, Philadelphia, PA 19104.

Ari Huverserian, University of Pennsylvania, c/o Renal Division; 1 Founders, 3400 Spruce Street, Philadelphia, PA, 19104.

Harold I. Feldman, University of Pennsylvania, Center for Clinical Epidemiology and Biostatistics, 922 Blockley, 423 Guardian Drive, Philadelphia, PA, 19104.


1. Rostand SG, Brunzell JD, Cannon RO, 3rd, Victor RG. Cardiovascular complications in renal failure. J Am Soc Nephrol. 1991;2(6):1053–1062. [PubMed]
2. USRDS Reference Table. Patient Survival. Annual Data Report: Atlas of End-Stage Renal Disease in the United States. 2008. pp. 585–636. Available from
3. Davis CL, Delmonico FL. Living-donor kidney transplantation: a review of the current practices for the live donor. J Am Soc Nephrol. 2005;16(7):2098–2110. [PubMed]
4. Mange KC, Joffe MM, Feldman HI. Effect of the use or nonuse of long-term dialysis on the subsequent survival of renal transplants from living donors. N Engl J Med. 2001;344(10):726–731. [PubMed]
5. Kasiske BL, Bia MJ. The evaluation and selection of living kidney donors. Am J Kidney Dis. 1995;26(2):387–398. [PubMed]
6. Segev DL, Gentry SE, Montgomery RA. Association between waiting times for kidney transplantation and rates of live donation. Am J Transplant. 2007;7(10):2406–2413. [PubMed]
7. Lunsford SL, Simpson KS, Chavin KD, Menching KJ, Miles LG, Shilling LM, et al. Racial disparities in living kidney donation: is there a lack of willing donors or an excess of medically unsuitable candidates? Transplantation. 2006;82(7):876–881. [PubMed]
8. Bloembergen WE, Port FK, Mauger EA, Briggs JP, Leichtman AB. Gender discrepancies in living related renal transplant donors and recipients. J Am Soc Nephrol. 1996;7(8):1139–1144. [PubMed]
9. Zimmerman D, Albert S, Llewellyn-Thomas H, Hawker GA. The influence of socio-demographic factors, treatment perceptions and attitudes to living donation on willingness to consider living kidney donor among kidney transplant candidates. Nephrol Dial Transplant. 2006;21(9):2569–2576. [PubMed]
10. Jindal RM, Ryan JJ, Sajjad I, Murthy MH, Baines LS. Kidney transplantation and gender disparity. Am J Nephrol. 2005;25(5):474–483. [PubMed]
11. Schaubel DE, Stewart DE, Morrison HI, Zimmerman DL, Cameron JI, Jeffery JJ, et al. Sex inequality in kidney transplantation rates. Arch Intern Med. 2000;160(15):2349–2354. [PubMed]
12. Alexander GC, Sehgal AR. Barriers to cadaveric renal transplantation among blacks, women, and the poor. Jama. 1998;280(13):1148–1152. [PubMed]
13. Epstein AM, Ayanian JZ, Keogh JH, Noonan SJ, Armistead N, Cleary PD, et al. Racial disparities in access to renal transplantation--clinically appropriate or due to underuse or overuse? N Engl J Med. 2000;343(21):1537–1544. 1532 p preceding 1537. [PubMed]
14. Young CJ, Gaston RS. Renal transplantation in black Americans. N Engl J Med. 2000;343(21):1545–1552. [PubMed]
15. Weng FL, Joffe MM, Feldman HI, Mange KC. Rates of completion of the medical evaluation for renal transplantation. Am J Kidney Dis. 2005;46(4):734–745. [PubMed]
16. Soucie JM, Neylan JF, McClellan W. Race and sex differences in the identification of candidates for renal transplantation. Am J Kidney Dis. 1992;19(5):414–419. [PubMed]
17. Boulware LE, Meoni LA, Fink NE, Parekh RS, Kao WH, Klag MJ, et al. Preferences, knowledge, communication and patient-physician discussion of living kidney transplantation in African American families. Am J Transplant. 2005;5(6):1503–1512. [PubMed]
18. Garg PP, Furth SL, Fivush BA, Powe NR. Impact of gender on access to the renal transplant waiting list for pediatric and adult patients. J Am Soc Nephrol. 2000;11(5):958–964. [PubMed]
19. Schold JD, Kaplan B, Chumbler NR, Howard RJ, Srinivas TR, Ma L, et al. Access to quality: evaluation of the allocation of deceased donor kidneys for transplantation. J Am Soc Nephrol. 2005;16(10):3121–3127. [PubMed]
20. Reese PP, Shea JA, Berns JS, Simon MK, Joffe MM, Bloom RD, et al. Recruitment of live donors by candidates for kidney transplantation. Clin J Am Soc Nephrol. 2008;3(4):1152–1159. [PubMed]
21. Bandura A. Self-efficacy: toward a unifying theory of behavioral change. Psychol Rev. 1977;84(2):191–215. [PubMed]
22. Zimet GD, Dahlem NW, Zimet SG, Farley GK. The Multidimensional Scale of Perceived Social Support. Journal of Personality Assessment. 1988;52:30–41.
23. Zimet GD, Powell SS, Farley GK, Werkman S, Berkoff KA. Psychometric characteristics of the Multidimensional Scale of Perceived Social Support. Journal of Personality Assessment. 1990;55(3–4):610–617. [PubMed]
24. U.S. Department of Health and Human Services. Social and Behavioral Interventions to Increase Solid Organ Donation. Announcement HRSA-09-189. [cited 2009 February 24]; Available from
25. Segev DL, Kucirka LM, Oberai PC, Parekh RS, Boulware LE, Powe NR, et al. Age and Comorbidities Are Effect Modifiers of Gender Disparities in Renal Transplantation. J Am Soc Nephrol. 2009 [PubMed]
26. Cunningham J, Cass A, Anderson K, Snelling P, Devitt J, Preece C, et al. Australian nephrologists' attitudes towards living kidney donation. Nephrol Dial Transplant. 2006;21(5):1178–1183. [PubMed]
27. Wolfe RA, McCullough KP, Schaubel DE, Kalbfleisch JD, Murray S, Stegall MD, et al. Calculating life years from transplant (LYFT): methods for kidney and kidney-pancreas candidates. Am J Transplant. 2008;8(4 Pt 2):997–1011. [PubMed]
28. Rao PS, Merion RM, Ashby VB, Port FK, Wolfe RA, Kayler LK. Renal transplantation in elderly patients older than 70 years of age: results from the Scientific Registry of Transplant Recipients. Transplantation. 2007;83(8):1069–1074. [PubMed]
29. Johnson DW, Herzig K, Purdie D, Brown AM, Rigby RJ, Nicol DL, et al. A comparison of the effects of dialysis and renal transplantation on the survival of older uremic patients. Transplantation. 2000;69(5):794–799. [PubMed]
30. Merion RM, Ashby VB, Wolfe RA, Distant DA, Hulbert-Shearon TE, Metzger RA, et al. Deceased-donor characteristics and the survival benefit of kidney transplantation. JAMA. 2005;294(21):2726–2733. [PubMed]
31. Middleton PF, Duffield M, Lynch SV, Padbury RT, House T, Stanton P, et al. Living donor liver transplantation--adult donor outcomes: a systematic review. Liver Transpl. 2006;12(1):24–30. [PubMed]
32. Young CJ, Gaston RS. African Americans and renal transplantation: disproportionate need, limited access, and impaired outcomes. Am J Med Sci. 2002;323(2):94–99. [PubMed]
33. Schweitzer EJ, Yoon S, Hart J, Anderson L, Barnes R, Evans D, et al. Increased living donor volunteer rates with a formal recipient family education program. Am J Kidney Dis. 1997;29(5):739–745. [PubMed]
34. Rodrigue JR, Cornell DL, Lin JK, Kaplan B, Howard RJ. Increasing live donor kidney transplantation: a randomized controlled trial of a home-based educational intervention. Am J Transplant. 2007;7(2):394–401. [PubMed]
35. Pradel FG, Suwannaprom P, Daniel Mullins C, Sadler J, Bartlett ST. Haemodialysis patients' readiness to pursue live donor kidney transplantation. Nephrol Dial Transplant. 2009 [PubMed]
36. Lunsford SL, Simpson KS, Chavin KD, Hildebrand LG, Miles LG, Shilling LM, et al. Racial differences in coping with the need for kidney transplantation and willingness to ask for live organ donation. Am J Kidney Dis. 2006;47(2):324–331. [PubMed]