By Hadley Wood, MD; David Goldfarb, MD; Herman S. Bagga, MD; Songhua Lin; Alun Williams; and Jesse Schold, PhD
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Kidney transplantation remains the gold standard for treating children with end-stage renal disease (ESRD), providing a known survival advantage compared with hemodialysis management.
Congenital disorders, such as anomalies of the upper and lower urinary tract and hereditary nephropathies, are disproportionately responsible for the development of chronic kidney disease (CKD) in children. In the United States, approximately 60 percent of pediatric CKD is attributed to such congenital disorders.2
We hypothesized that advancements in the management of patients with congenital urinary tract disorders may slow renal demise and result in delayed renal transplant within these patients. Furthermore, such advances could translate into improved renal transplant graft and patient survival.
Checking transplant recipient data
To test our hypothesis, we used the Scientific Registry of Transplant Recipients (SRTR) database of transplant statistics collected by the Organ Procurement and Transplantation Network, which is a collection of hospitals and organ procurement organizations across the United States. Since 1987, the SRTR has maintained comprehensive information on all solid organ transplants in the country, and includes current and past information on the full spectrum of transplant activity. Data include information on organ donors, candidates and recipients; as well as organ-specific and patient outcomes.
The SRTR was queried to identify first renal transplant and graft and patient survival data within congenital uropathy (CU) and patients with congenital pediatric kidney disease (CPKD) between 1996 and 2012.
Those in the CPKD group were substantially older at age of first transplant than were those with CU, resulting in differences between the two groups in renal transplant donor and recipient variables. On age-matched comparison, most variables were not significantly different between the two groups, including cognitive ability, body mass index and rates of diabetes across all age groups. A notable exception was hypertension. Among those 35 to 49 years old, individuals with CPKD had higher rates of hypertension compared with CU patients (72 percent vs 81 percent, P < 0.0001). Among those 12 to 17 years old, those with CU had higher rates of hypertension compared with CPKD patients (46 percent vs 40 percent, P = 0.018).
Trend toward later age at first transplant
The average age of first transplant did not significantly change during the study interval (Figure 1). However, analysis of individual age groups reveals several significant trends (Figures 2 and 3).
When considering graft survival (Figure 4) at 5 years, both groups demonstrated approximately 90 percent survival; however, at 10-year follow-up, CU patients had better graft survival than did CPKD patients (80.7 percent vs 75.9 percent, P < 0.001). When considering patient survival after renal transplant, the groups again had similar survival at 5 years (93.2 percent for CU patients vs 95 percent for CPKD patients, P > 0.05). Correspondingly, at 10 years, CU patients had significantly better patient survival than did CPKD patients (82.3 percent vs 77 percent, P < 0.001). When comparing CU and CPKD patients within age groups, however, graft and patient survival differences were not significant.
This study demonstrates that patients with congenital uropathies and nephropathies indeed trended toward later age at first transplant during the 14-year period we examined in the SRTR database. Furthermore, after matching CU and CPKD patients for age, we demonstrated equivalent 10-year graft survival between the two groups.
What’s behind the improved outcomes?
We postulate that these findings can be explained by one or more of the following changes during the study period:
Among patients with CPKD, subsequent management strategies include appropriate hypertension management, hormone supplementation, protein replacement, nutritional supplementation and, when appropriate, medical therapies such as steroid or immunosuppressive agents. Care for patients with CU such as those with posterior urethral valves, prune belly syndrome, congenital neuropathic bladders, obstructive megaureters and significant ureteral reflux includes appropriate use of anticholinergics, intermittent catheterization, antibiotics and appropriate surgical intervention.
Dr. Wood is a Staff Physician in Cleveland Clinic’s Center for Genitourinary Reconstruction.
Dr. Goldfarb is Surgical Director, Renal Transplantation Program, in Cleveland Clinic’s Glickman Urological & Kidney Institute.