Results
Recipient Characteristics by Infection Groups: HCV Mate Analysis
The study population consisted of 3400 kidney transplant recipients (1700 HCV+ and 1700 HCV−). Transplant recipients in the HCV+ group were similar in age (52.6 vs. 52.1 years) and more likely to be male (70.8% vs. 60.8%), African-American (51.9% vs. 33.8%), sensitized with peak PRA >30% (31.1% vs. 26.9%), re-transplants (17.8% vs. 12.4%), nonprivately insured (79.8% vs. 75.6%), dialysis duration >3 years (67.5% vs. 57.0%) and less likely to be obese (29.5% vs. 35.8%) compared to the HCV− group. The two groups were similar in terms of the other characteristics evaluated (Table 1a).
Patient and Graft Survival: HCV Mate Analysis
Time to event curves are provided in Figure 1 for HCV+ versus HCV− cases. Unadjusted 3-year patient survival was 87.5% in the HCV+ and 89.1% in the HCV− groups. Unadjusted 3-year DCGS was 88.3% and 90.5%, respectively. On multivariate analysis, HCV+ was significantly associated with DCGS (adjusted hazard ratio [aHR] 1.24; 95% CI 1.04–1.47) and patient survival (aHR 1.24; 95% CI 1.06–1.45) compared to the HCV− group (Table 2a).
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Figure 1.
Kaplan–Meier plots of (a) overall patient survival and (b) death-censored graft survival for hepatitis C virus positive (HCV+) and negative (HCV−) kidney transplant recipients.
1-year Acute Rejection: HCV Mate Analysis
Acute rejection at 1 year occurred in 11.4% of HCV+ and 10.8% of HCV− cases. On multivariate analysis, HCV+ was not a risk factor for acute rejection (adjusted odds ratio [aOR] 1.04; 95%CI 0.82–1.31) (Table 2a).
Recipient Characteristics by Infection Groups: HIV Mate Analysis
There were 486 kidney transplant recipients (243 HIV+ and 243 HIV−). Recipients in the HIV+ group were also HCV+ in 14.8%. The control group comprised recipients without HIV or HCV. Transplant recipients in the HIV+ group were significantly younger (48.1 vs. 53.2 years) and significantly more likely to be African-American (81.5% vs. 42.0%), male (77.0% vs. 66.3%), have a dialysis duration >3 years (83.5 vs. 60.5%), CIT >24 h (30.6% vs. 22.4%) and to be nonprivately insured (87.2% vs. 79.8%) compared to HIV− recipients. HIV+ recipients were significantly less likely to be obese (23.0% vs. 34.9%), re-transplanted (2.9% vs. 13.2%), have a comorbidity (6.2% vs. 13.2%) and to have diabetes as the primary etiology of ESRD (11.1% vs. 30.9%); compared to the HIV− group. The two groups were similar in terms of HLA mismatch and sensitization (Table 1b).
The coinfected recipients were significantly more likely to have diabetes as the primary etiology of ESRD (22.2% vs. 9.2%) and had a higher mean age (51.1 vs. 47.5 years) compared to HIV monoinfected recipients (Table 1c).
Patient and Graft Survival: HIV Mate Analysis
Time-to-event curves are provided in Figure 2 for HIV+ (HIV+ with or without HCV) versus HIV− cases and further stratified in Figure 3 for the, HIV+/HCV−, HIV+/HCV+ and HIV−/HCV−groups. The HIV+ group graft survival curves demonstrate similar attrition from early posttransplantation through follow-up. The HIV+/HCV+ group patient survival curves also demonstrate similar attrition starting early posttransplantation; however, differences in attrition of graft survival in the coinfected group manifest themselves after the second year posttransplantation. Unadjusted 3-year patient survival in the HIV+ and HIV− groups was 85.1% and 89.6% and unadjusted 3-year DCGS was 86.9% and 86.4%, respectively. On multivariable analysis, HIV+ conferred comparable DCGS (aHR 0.85, 95% CI 0.48, 1.51) and patient survival (aHR 0.80, 95% CI 0.39, 1.64) compared to the HIV−/HCV− group. The presence of HCV coinfection was a significant independent risk factor for DCGS (aHR 2.33; 95% CI 1.06, 5.12) and for patient survival (aHR 2.88; 95% CI 1.35, 6.12) (Table 2b).
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Figure 2.
Kaplan–Meier plots of (a) overall patient survival and (b) death-censored graft survival for HIV+ (with or without HCV) compared to HIV− kidney transplant recipients.
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Figure 3.
Kaplan–Meier plots of (a) overall patient survival and (b) death-censored graft survival for HIV+/HCV+, HIV+/HCV− and HIV−/HCV− kidney transplant recipients
1-year Acute Rejection: HIV-mate Analysis
Acute rejection at 1 year occurred in 21.2%, 18.5% and 8.3% of the patients in the HIV+/HCV−, HIV+/HCV+, HIV−/HCV−, groups, respectively. On multivariable analysis, neither HIV+ (aOR 2.01, 95% CI 0.91–4.43) nor HCV coinfection (aOR 1.10, 95% CI 0.36–3.32) was a significant risk factor for 1-year acute rejection (Table 2b).
Sensitivity Analyses
Additional analyses were conducted to evaluate the robustness of the primary results. There was little impact on the magnitude of the hazard ratio or the significance of the findings of DCGS after exclusion of cases with missing data. Additionally, a univariate comparison of time-to-event curves of 36 coinfected patients (HIV+/HCV+) directly with their respective 36 noninfected (HIV−/HCV−) mate kidney recipients revealed similar findings to the full analysis (3-year patient survival 79.2% vs. 91.5%; 3-year graft survival 71.9% vs. 87.7%, respectively). A multivariable analysis could not be performed because of small sample size.
Additional analyses were performed to confirm the acute rejection findings. The results were robust to (1) application of a multivariable generalized estimating equation to account for the possibility of clustering due to the mate analysis design and to (2) a model including only patients with at least 1 year of graft survival based on their status as being at-risk for these events and given that no exact date is available for these outcomes in the database.