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Molinari et al. Hepatoma Res 2018;4:56 I http://dx.doi.org/10.20517/2394-5079.2018.71 Page 3 of 15

and outcomes of patients undergoing LT for HCC in the United States are lacking, the primary aim of this
study was to assess if African American had short- and long-term outcomes similar to recipients of other
ethnic groups.

METHODS
Study design
The United network for organ sharing (UNOS) standard transplant analysis and research (STAR) files were
used to identify a retrospective cohort of patients who underwent LT for HCC in the United States between
1 Jan 2002 and 30 Jun 2013. The study was conducted and reported per recommendations from STROBE
statement [28,29] and did not require approval by the ethics review board of our institution.

Rationale and aims of the study
There has been some controversy regarding the possible reasons why some ethnic groups have inferior
[33]
survival than Caucasian recipients after LT [30-32] . Nair et al. have previously reported that being African
American or Asian American were risk factors for inferior long-term outcomes after LT. On the other hand,
[34]
Lee et al. did not find any association between race and post-LT outcomes after adjusting for age, gender,
[30]
total bilirubin, creatinine and prothrombin time. In more recent years, Wong et al. analyzed the 2002-
2012 STAR files and concluded that African Americans had significantly lower survival compared with non-
Hispanic whites affected by HCV, alcoholic liver disease, and HCC after adjusting for several demographic
and clinical characteristics. To the best of our knowledge this was the only study that assessed the outcomes
of LT recipients stratified by their ethnicity after the MELD score was introduced in the USA for the
allocation of liver grafts. Although this study had the advantage of including a large number of patients,
it was limited by the fact that several predictors of long-term survival were not included in the final Cox-
regression analysis, and that the study was not specifically designed for patients with HCC. Because of these
limitations, we performed a retrospective analysis of the STAR files with the primary aim of testing the null
hypothesis, that there were no significant differences in the overall survival of patients with documented
HCC and who belonged to different ethnic groups.

Inclusion and exclusion criteria
All adults (age ≥ 18 years) undergoing LT for HCC were candidates for this study. No restriction of race,
citizenship or UNOS region were applied. Recipients of LT for other primary and secondary malignancies
(e.g., cholangiocarcinoma, hepatoblastoma, hemangiosarcoma, neuroendocrine metastasis) were excluded.
Other exclusion criteria were: transplants from grafts recovered from living or donors after cardiac death,
split grafts, multi-visceral or redo transplants, and LT performed across ABO incompatible blood groups.
Additional exclusion criteria were lack of records on short and long-term outcomes, the absence of HCC in
the explanted liver or the presence of variables with values that were deemed implausible for adult recipients
[35]
or for deceased donor LTs . Cutoffs for those values were: recipient height either ≤ 120 cm or ≥ 240 cm, cold
ischemia time ≥ 24 h. No imputations of missing data were performed, and recipients who had more than
10% of unreported values were excluded.

Variables and outcomes
Variable collected for LT recipients were age at the time of transplant, sex, donor and recipient body mass
index (BMI), ethnicity, presence of renal failure requiring hemodialysis before surgery, history of diabetes
(either type I or II), mortality within 30-, 60-, 90-day and 1 year after surgery, main cause of death, date
of death or date of last follow up, cold ischemia time (h), UNOS region where patients were transplanted.
Additional variables collected for the donors were age, sex, height and weight or BMI.

Recipient overall survival was estimated by the difference between the date of transplantation and the date of
death from any cause using the Kaplan-Meier method. Censoring was used for recipients who were still alive