CKD

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To define characteristics of uninephric patients with CKD in five public renal specialty ... Argueso, L.R., et al., Prognosis of patients with unilateral renal agenesis.
Characteristics of Uninephric Chronic Kidney Disease (CKD) Patients A. Mallett , A. Salisbury , Z. Wang , H. Healy for the CKD.QLD Collaborative 1,2,3

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"CKD.QLD (Chronic Kidney Disease in Queensland), now approaching its fifth year, is a collaborative, multidisciplinary research and practice improvement network, developed as an initiative of the University of Queensland, Queensland University of Technology, and Queensland Health. CKD.QLD has four major research platforms: 1. A CKD Surveillance Registry, encompassing CKD patients referred to all major public renal units within the State of Queensland 2. Practice Improvement 3. Biomarker Research, and 4. Clinical Trials To learn more, please visit our website: www.ckdqld.org.

, G. John , W.E. Hoy

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CKD.QLD 2 Centre of Chronic Disease, School of Medicine, University of Queensland, Brisbane, Australia 3 Department of Renal Medicine, Royal Brisbane and Women’s Hospital, Brisbane, Australia 1

Aim

Figure 1. Uninephric CKD.QLD Patients Fig 1b. Uninephric Subgroups

Fig 1a. Identified Cases

To define characteristics of uninephric patients with CKD in five public renal specialty practices in Queensland.

n=2359

n=136

3.6% 0.8% 1.3%

Background

7.4%

55.9%

CKD due to uninephria is infrequently reported. Absolute nephron number has however been demonstrated to have clinically relevant implications [1]. This effect is observed in those with either one or two functioning kidneys [2].

2.9%

11.8%

9.6%

Cohort studies of congenitally uninephric patients have demonstrated an increased risk of proteinuria, hypertension and renal dysfunction [3, 4]. Whilst these patients may physiologically compensate with their contralateral normally functioning kidney [5] this adaptation may not be entirely durable into adulthood [6]. Renal function however often remains preserved during childhood and young adulthood [7]. Long term follow up of thse patients is presently receommended [8-10] continuing into and throughout adulthood. For those undergoing nephrectomy similar outcomes have been demonstrated [6] and followup regimens suggested [11]. This includes study of those undergoing nephrectomy in childhood [12], partial vs radical nephrectomy in adulthood [13, 14] and living kidney donation [15]. Even thouh living kidney donors represent a highly selected population, a minority of living kidney donors develop hypertension or proteinuria post-donation [16]. Despite this, renal function does not necessarily decline disproportionatley either in the acute post-donation period [17] nor more chronically [16]. There is a lack of precision associated with glomerular filtration rate estimates based upon serum creatinine measurements in uninephric patients [18]. This highlights the need for conscientious longterm followup of these patients regardless of the etiology of uninephria. 0.9% of Australian and New Zealand patients starting renal replacement therapy (RRT) in 2011 had either “Loss of Single Kidney” (n=6) or “Congenital Renal Hypoplasia and Dysplasia” (n=20) [19]. Its frequency in the general CKD population is undefined. We propose that this group has distinct characteristics compared to the broader Australasian CKD population.

94.2%

12.5% 1a. Nephrectomy (Surgical) 1b. Nephrectomised (Functional) 2a. Partial Nephrectomy 2b. Atrophic/Dysplastic 3a. Congenital Single Kidney 3c. Congenital Malformation

1. Nephrectomised 2. Partial Nephrectomy/Atrophic 3. Congenital All Others

Figure 2. CKD Stages of Uninephric CKD.QLD Populations 50%

Nephrectomised Partial/Atrophic Congenital

45%

n=86 n=20 n=30

40% 35% 30% 25% 20% 15% 10% 5%

Methods

0%

CKD.QLD is a registry and research platform involving all consenting patients in public renal practices in Queensland (~10,800). Uninephric patients among the first 2,359 enrolled at 5 hospital sites were sought through primary renal disease coding for nephrectomy, hypo/dysplastic, atrophic, and congenital kidneys. They were compared to all patients in the CKD.QLD registry.

1

2

3A

3B

4

CKD Stage Partial Nephrectomy/Atrophic

Nephrectomised

Congenital

Figure 3. Age Groups of Uninephric and Total CKD.QLD Patients 3a. Uninephric CKD.QLD Subgroups

Results 136 uninephric patients were identified, or 5.8% of the total CKD cohort (Figure 1). Of these 76 (56%) had a surgical nephrectomy, 17 (12.5%) had a congenital malformation, 16 (11.7%) had an atrophic/dysplastic kidney, 13 (9.5%) had congenital single kidney, 10 (7.3%) had a functional nephrectomy, and 4 (3%) had a partial nephrectomy. Uninephric patients in total and by subgroups were most commonly CKD stage 3b (30%) and 4 (26%) (Figure 2). Their mean age was 64.2 years, compared to 65.5 years for CKD.QLD (Figure 3). 47% of uninephric patients were female vs 45% of the CKD.QLD registry (Figure 4).

45% 40% 35%

Nephrectomised n=86 Mean=66.8yrs

Partial/Atrophic n=20 Mean=73.2yrs

3b. Total CKD.QLD Cohort Total n=136 Mean=64.2yrs

Congenital n=30 Mean=49.9yrs

25%

20%

20%

15%

15%

10%

10%

5%

5%

0%

0%

0-4

5 - 14

15 - 24 25 - 34 35 - 44 45 - 54 55 - 64 65 - 74 75 - 84

10. 11.

15. 16. 17. 18. 19.

Unknown

0-4

5 - 14

Female n=1071 Mean=64.4yrs

Total n=2359 Mean=65.5yrs

15 - 24 25 - 34 35 - 44 45 - 54 55 - 64 65 - 74 75 - 84

85

Unknown

Age Group (yrs)

Figure 4. Gender of Uninephric and Total CKD.QLD Populations Fig 4a. All Uninephric

Fig 4b. Total CKD.QLD

n=136

n=2359

47%

45%

53%

55%

Male

Female

Figure 5. Living Kidney Donors and Nephrectomised Patients Surgically Nephrectomised Patients n=76 Non-Living Kidney Donors

Living Kidney Donors Gender

n=6

Gender

92%

Mean Age 63yrs

Mean Age 67.5yrs

37%

8%

100%

n=6

63%

CKD Stage 60% 50% 40% 30% 20% 10% 0%

CKD Stage Living Kidney Donor Other Reason for Nephrectomy

1

2

3a

3b

CKD Stage

4

5

Male

Female

60% 50% 40% 30% 20% 10% 0%

1

2

3a

3b

4

5

CKD Stage

Great state. Great opportunity.

HMMU Sep’13 1185_jk_P3

12. 13. 14.

85

Male n=1288 Mean=66.4yrs

Age Group (yrs)

References

8. 9.

35%

25%

There are substantial numbers of uninephric patients in this CKD group and a greater proportion than represented in RRT data. They are younger that the broader CKD.QLD population and have greater prevalence in CKD stages 2 to 5. The identification of 6 living kidney donors is of concern. These findings support the suggestion for ongoing clinical follow up of uninephric patients.

3. 4. 5. 6. 7.

40% 30%

Conclusions

Hoy, W.E., et al., Nephron number, hypertension, renal disease, and renal failure. J Am Soc Nephrol, 2005. 16(9): p. 2557-64. Hoy, W.E., et al., Reduced nephron number and glomerulomegaly in Australian Aborigines: a group at high risk for renal disease and hypertension. Kidney Int, 2006. 70(1): p. 104-10. Argueso, L.R., et al., Prognosis of patients with unilateral renal agenesis. Pediatr Nephrol, 1992. 6(5): p. 412-6. Westland, R., et al., Renal injury in children with a solitary functioning kidney--the KIMONO study. Nephrol Dial Transplant, 2011. 26(5): p. 1533-41. van Vuuren, S.H., et al., Compensatory enlargement of a solitary functioning kidney during fetal development. Ultrasound Obstet Gynecol, 2012. Abou Jaoude, P., et al., Congenital versus acquired solitary kidney: is the difference relevant? Nephrol Dial Transplant, 2011. 26(7): p. 2188-94. Vu, K.H., et al., Renal outcome of children with one functioning kidney from birth. A study of 99 patients and a review of the literature. Eur J Pediatr, 2008. 167(8): p. 885-90. Chevalier, R.L., When is one kidney not enough? Kidney Int, 2009. 76(5): p. 475-7. Zaffanello, M., et al., Are children with congenital solitary kidney at risk for lifelong complications? A lack of prediction demands caution. Int Urol Nephrol, 2009. 41(1): p. 127-35. Stefanowicz, J., et al., Renal function and solitary kidney disease: Wilms tumour survivors versus patients with unilateral renal agenesis. Kidney Blood Press Res, 2012. 35(3): p. 174-81. Provoost, A.P. and B.M. Brenner, Long-term follow-up of humans with single kidneys: the need for longitudinal studies to assess true changes in renal function. Curr Opin Nephrol Hypertens, 1993. 2(4): p. 521-6. Baudoin, P., A.P. Provoost, and J.C. Molenaar, Renal function up to 50 years after unilateral nephrectomy in childhood. Am J Kidney Dis, 1993. 21(6): p. 603-11. Mariusdottir, E., et al., Kidney function following partial or radical nephrectomy for renal cell carcinoma: A population-based study. Scand J Urol, 2013. Kaushik, D., et al., Overall Survival and Development of Stage IV Chronic Kidney Disease in Patients Undergoing Partial and Radical Nephrectomy for Benign Renal Tumors. Eur Urol, 2013. 64(4): p. 600-6. Goldfarb, D.A., et al., Renal outcome 25 years after donor nephrectomy. J Urol, 2001. 166(6): p. 2043-7. Fehrman-Ekholm, I., et al., No evidence of accelerated loss of kidney function in living kidney donors: results from a cross-sectional follow-up. Transplantation, 2001. 72(3): p. 444-9. Krohn, A.G., D.A. Ogden, and J.H. Holmes, Renal function in 29 healthy adults before and after nephrectomy. JAMA, 1966. 196(4): p. 322-4. Tan, J.C., et al., Imprecision of creatinine-based GFR estimates in uninephric kidney donors. Clin J Am Soc Nephrol, 2010. 5(3): p. 497-502. ANZDATA, The 35th Annual Report: ANZDATA Registry Report 2012, 2012, Australia and New Zealand Dialysis and Transplant Registry: Adelaide.

45%

30%

Among the 76 surgically nephrectomised patients, 6 were living kidney donors while 70 were for “other/non-living kidney donor” reasons (Figure 5). All living donors were female compared to 37% of the “other” group. CKD stage 3a was most common in living donors (50%) and CKD stage 3b most common in the “other” group (34%). Living donor mean age was 63 years vs 67.5 years in the non-living kidney donor group.

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