Kidney Transplantation: Which Variables Should Be Improved?

Hypoalbuminemia is a risk factor for invasive fungal infections and poor outcomes in infected kidney transplant recipients

INTRODUCTION

Invasive fungal infections (IFI), are estimated to occur in 2%-14% of kidney transplant recipients (KTRs) in the current era of immune suppression and are associated with high mortality rates. We hypothesized that hypoalbuminemia in KTRs is a risk factor for IFI and would be associated with poor outcomes.

METHODS

In this study, using data from a prospective cohort registry, we describe the frequency of IFI due to Blastomycosis, Coccidioidomycosis, Histoplasmosis, Aspergillosis, and Cryptococcus in KTRs with serum albumin levels measured 3-6 months before diagnosis. Controls were selected based on incidence density sampling. KTRs were divided into three groups based on the pre-IFI serum albumin level: normal (≥4 g/dL), mild (3-4 g/dL), or severe (<3 g/dL) hypoalbuminemia. Outcomes of interest were uncensored graft failure after IFI and overall mortality.

RESULTS

A total of 113 KTRs with IFI were compared with 348 controls. The incidence rate of IFI among individuals with normal, mild, and severe hypoalbuminemia was 3.6, 8.7, and 29.3 per 100 person-years, respectively. After adjustment for multiple variables, the trend for risk of uncensored graft failure following IFI was greater in KTRS with mild (HR = 2.1; 95% CI, .75-6.1) and severe (HR = 4.47; 95% CI, 1.56-12.8) hypoalbuminemia (P-trend < .001) compared to those with normal serum albumin. Similarly, mortality was higher in severe hypoalbuminemia (HR = 1.9; 95% CI, .67-5.6) compared to normal serum albumin (P-trend < .001).

CONCLUSION

Hypoalbuminemia precedes the diagnosis of IFI in KTRs, and is associated with poor outcomes following IFI. Hypoalbuminemia may be a useful predictor of IFI in KTRs and could be incorporated into screening algorithms.

Pre-transplant hypoalbuminemia is not associated with worse short-term outcomes among kidney transplant recipients

INTRODUCTION

Serum albumin is an indicator of overall health status, but it remains unclear how pre-transplant hypoalbuminemia is associated with early post-transplant outcomes.

METHODS

This study included all adult kidney transplant recipients (KTRs) at our center from 01/01/2001-12/31/2017 with serum albumin measured within 30 days before transplantation. KTRs were grouped based on pretransplant albumin level normal (≥4.0 g/dL), mild (≥3.5 - < 4.0g/dL), moderate (≥3.0 - < 3.5g/dL), or severe hypoalbuminemia (<3.0g/dL). Outcomes of interest included: length of hospital stay (LOS), readmission within 30 days, delayed graft function(DGF), and re-operation related to post-transplant surgical complications. We also analyzed rejection, graft failure, and death within 6 months post-transplant.

RESULTS

A total of 2807 KTRs were included 43.6% had normal serum albumin, 35.3% mild, 16.6% moderate, and 4.5% severe hypoalbuminemia. Mild and moderate hypoalbuminemia were associated with a shorter LOS by 1.22 (p < 0.001) and 0.80 days (p = 0.01), respectively, compared to normal albumin. Moderate (HR: 0.58; 95% CI: 0.37-0.91; p = 0.02) and severe hypoalbuminemia (HR: 0.21; 95% CI: 0.07-0.68; p = 0.01) were associated with significantly lower rates of acute rejection within 6 months post-transplant.

CONCLUSION

Patients with pre-transplant hypoalbuminemia have post-transplant outcomes similar to those with normal serum albumin, but with a lower risk of acute rejection based on the degree of hypoalbuminemia.

Serum Albumin Level Before Kidney Transplant Predicts Post-transplant BK and Possibly Cytomegalovirus Infection

INTRODUCTION

Opportunistic viral infections cause extensive morbidity and mortality in kidney transplant recipients (KTRs). Low serum albumin levels before and after transplant have been associated with negative outcomes. However, it is uncertain whether serum albumin levels before transplantation are associated with the risk for post-transplantation opportunistic BK polyomavirus (BKV) or cytomegalovirus (CMV).

METHODS

We reviewed all KTRs transplanted at our institution between 1 January 2005 and 31 December 2015 with serum albumin measured within 45 days before transplantation in a retrospective observational cohort study. Selected patients were stratified into 3 groups: normal albuminemia (≥3.5 g/dl), moderate hypoalbuminemia (3.49-2.5 g/dl), and severe hypoalbuminemia (<2.5 g/dl). Patients were observed for post-transplantation BKV or CMV according to standard of care.

RESULTS

We included 1717 patients in this study; 72.3% had normal serum albumin, 26.3% had moderate hypoalbuminemia, and 1.5% had severe hypoalbuminemia. Moderate and severe hypoalbuminemia incurred a higher risk for BKV compared with normal serum albumin levels in univariable analysis (moderate hypoalbuminemia: hazard ratio [HR] = 1.5; 95% confidence interval [CI], 1.14-1.90; P = .003); severe hypoalbuminemia: HR = 2.15; 95% CI, 1.01-4.56; P = 0.05). Although not significant after multivariable adjustment, there was still 18% increased risk in moderate hypoalbuminemia and 64% in severe hypoalbuminemia for BKV compared with the normal albumin group. Moderate hypoalbuminemia was associated with a higher risk for CMV infection than normal serum albumin levels in multivariable analysis, although it was not statistically significant (HR = 1.15; 95% CI, 0.36-3.64; P = 0.81).

CONCLUSIONS

These findings suggest that pretransplantation hypoalbuminemia is associated with a higher risk for post-transplantation BKV and possibly CMV. More intense screening is warranted for these viruses in recipients with pretransplant hypoalbuminemia.

Perioperative hemoglobin decrement as an independent risk of poor early graft function in kidney transplantation

OBJECTIVE

Perioperative change of hemoglobin concentration (Hb) was associated with acute kidney injury in patients who underwent non-cardiac surgery, but has never been investigated in kidney transplant patients. This study aimed to observe the effects of perioperative Hb change on early graft function in kidney transplant recipients.

RESULTS

A total of 269 kidney transplant patients were enrolled, of whom 98 (36.4%) developed poor early graft function (PEGF), and 171 (63.6%) had immediate graft function. Comparing two groups, patients with PEGF had a greater decremental change of Hb (-1.60 [-2.38,-0.83] vs. -0.70 [-1.35,0.20] g/dL, respectively; p < 0.001). A Hb cut-point of -1.35 g/dL was obtained from ROC analysis. Multivariate analysis showed that perioperative Hb decrement greater than 1.35 g/dL was an independent risk of PEGF (adjusted OR of 2.52, 95% CI 1.11-5.72; p = 0.026). Subgroup analysis revealed deceased donor kidney transplant (DDKT; n = 126) (adjusted OR of 2.89, 95% CI 1.11-7.55; p = 0.029), but not living donor kidney transplantation (LDKT; n = 143) (adjusted OR of 1.68, 95% CI 0.23-12.15; p = 0.606), was influenced by the perioperative Hb decrement. In conclusion, this study suggests that decremental change in perioperative Hb greater than 1.35 g/dL may serve as a modifiable factor of PEGF in DDKT.

Diffusion-Weighted imaging and diffusion tensor imaging detect delayed graft function and correlate with allograft fibrosis in patients early after kidney transplantation

PURPOSE

To combine diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for detection of allograft dysfunction in patients early after kidney transplantation and to correlate diffusion parameters with renal function and renal histology of allograft biopsies.

MATERIALS AND METHODS

Between day 4 and 11 after kidney transplantation 33 patients with initial graft function and 31 patients with delayed graft function (DGF) were examined with a 1.5T magnetic resonance imaging (MRI) scanner. DTI and DWI sequences were acquired and fractional anisotropy (FA), apparent diffusion coefficient (ADCmono), pure diffusion (ADCdiff ), and the perfusion fraction (Fp) were calculated. Kidney biopsies in 26 patients were analyzed for allograft pathology, ie, acute tubular injury, inflammation, edema, renal fibrosis, and rejection. Histological results were correlated with MRI parameters.

RESULTS

In the renal medulla FA (0.25 ± 0.06 vs. 0.29 ± 0.06, P < 0.01) and ADCmono (1.73 ± 0.13*10(-3) vs. 1.93 ± 0.16*10(-3) mm(2) /s, P < 0.001) were significantly reduced in DGF patients compared with patients with initial function. For ADCdiff and Fp similar reductions were observed. FA and ADCmono significantly correlated with renal function (r = 0.53 and r = 0.57, P < 0.001) and were inversely correlated with the amount of renal fibrosis (r = -0.63 and r = -0.65, P < 0.05).

CONCLUSION

Combined DTI and DWI detected allograft dysfunction early after kidney transplantation and correlated with allograft fibrosis. J. Magn. Reson. Imaging 2016;44:112-121.