Advanced CKD Study

1. Advanced CKD Study Daniel Ford UKRR Annual Audit MeetingJune 2009

2. Overview Data collection issues • Definition of the date of start of dialysis Pre-RRT study results • Associations with the rate of kidney function decline in the final year pre-RRT

3. Pre-RRT Study Objectives To look at what factors are associated with: • eGFR decline • Hb decline • Survival during the final year prior to starting RRT Methods 4,722 incident RRT patients from 7 centres from 2001-2006 Extracted laboratory data • 0, 1, 2, 3, 4, 5, 6, 12 months pre-RRT

6. n=826

7. Distinction between “acute” and “chronic” HD • Definition of start of PD

8. Definition of “acute HD” Of 826 records checked, 14.9% started RRT on “acute” HD with no retrospective timeline change

9. Definition of “acute HD” “If a patient started as ‘acute’ renal failure and did not recover, the date of start of renal replacement should have been backdated to the start of acute dialysis.”

10. “If a patient started as ‘acute’ renal failure and did not recover, the date of start of renal replacement should have been backdated to the start of acute dialysis.” Appendix B of Annual Report (online only) Methodology or instruction to clinicians? Definition of “acute HD”

11. Definition of start of PD • 75/826 had some evidence of PD exchanges prior to documented start date • What is the date of start of PD?

12. Definition of start of PD • 75/826 had some evidence of PD exchanges prior to documented start date • What is the date of start of PD? • Insertion of PD catheter? • First fluid exchange after PD catheter? • Date of start of CAPD training? • Date of PD independence?

13. Dubious eGFR trend pre-RRT Existing eGFR at start studies Survival data Late presentation data Consequences of inaccurate RRT start date

14. What needs to be done? • UKRR • Redefine date of start of HD (acute/chronic) • National • Consensus on date of start of PD

15. If a patient started as ‘acute’ renal failure and did not recover, the date of start of renal replacement should have been backdated to the start of acute dialysis. Many nephrologists do not do this and where this period of acute dialysis has been recorded in local systems, the UKRR will use this data to backdate the start of RRT. Date of start of HD Appendix B UKRR 11th Annual Report, December 2008

16. If a patient started as ‘acute’ renal failure and did not recover, the date of start of renal replacement should have been backdated to the start of acute dialysis. Many nephrologists do not do this and where this period of acute dialysis has been recorded in local systems, the UKRR will use this data to backdate the start of RRT. Date of start of HD Appendix B UKRR 11th Annual Report, December 2008 Letter to RA membership C Tomson, M Raftery, 23rd March 2009

17. If a patient started as ‘acute’ renal failure and did not recover, the date of start of renal replacement should have been backdated to the start of acute dialysis. Many nephrologists do not do this and where this period of acute dialysis has been recorded in local systems, the UKRR will use this data to backdate the start of RRT. Date of start of HD Appendix B UKRR 11th Annual Report, December 2008 Letter to RA membership C Tomson, M Raftery, 23rd March 2009

18. Date of start of PD The date of start of peritoneal dialysis is defined as the date of first PD fluid exchange given with the intention of causing solute or fluid clearance This contrasts with an exchange solely for confirming or maintaining catheter patency. In general, exchanges which are part of PD training should be considered as the start of PD. Chapter 7: Survival in UK RRT patients. UKRR 11th Annual Report, December 2008

19. Summary of timeline issues Inaccurate timeline returns are common This has implications for a number of UKRR analyses, including: • Survival • Rates of late presentation • eGFR at start of RRT This may not be unique to the UKRR Efforts are being made to re-define and publicise problematic definitions

20. Pre-RRT Study Results

21. Pre-RRT study • 7 centres • 2001-2006 • n=4,722 • Excluded patients • presenting late (<3m) • with missing data from relevant analyses • with anomalous timeline data • with fewer than 4 eGFR results

22. eGFR statistical analyses- Retha Steenkamp • Least-square analysis • Linear regression line fitted on an individual-patient basis • Mean rate of eGFR decline calculated • Multi-level model • Quadratic model Adjusted for: • Age, gender, ethnicity, PRD

23. Results • Age • Ethnicity • Primary renal disease • Systolic BP • Diastolic BP • Time from first renal presentation

24. Rate of eGFR decline pre-RRT by age group (adjusted for gender, ethnicity and PRD) (95% CIs) • Hunsicker LG, et al. Kidney Int 1997;51:1908-1919. • Levin A, et al. American Journal of Kidney Diseases 2008;52:661-671. • Eriksen BO, et al. Kidney Int 2006;69:375-382.

25. Modelled eGFR pre-RRT by age group

26. Modelled eGFR pre-RRT by age group

27. Modelled eGFR pre-RRT by age group

28. Modelled eGFR pre-RRT by age group

29. Modelled eGFR pre-RRT by age group

30. Rate of eGFR decline pre-RRT by ethnicity (adjusted for age, gender and PRD) (95% CIs) • McClellan W, et al. J Am Soc Nephrol 2006;17:1710-1715. • Clase CM, et al. J Am Soc Nephrol 2002;13:1338-1349. • Coresh J, et al. American Journal of Kidney Diseases 2003;41:1-12. • Hsu C-Y, et al. J Am Soc Nephrol 2003;14:2902-2907.

31. Modelled eGFR pre-RRT by ethnicity (adjusted for age, gender and PRD)

32. Rate of eGFR decline pre-RRT by primary renal disease (adjusted for age, gender and ethnicity) (95% CIs) • Hemmelgarn BR, et al. Kidney Int 2006;69:2155-2161. • Levin A, et al. American Journal of Kidney Diseases 2008;52:661-671. • Jungers P, et al. Nephrol Dial Transplant 1995;10:1353-1360.

33. Modelled eGFR pre-RRT by primary renal disease (adjusted for age, gender and ethnicity)

34. Rate of eGFR decline by systolic BP at 6 months pre-RRT (adjusted for age, gender, ethnicity and PRD) (95% CIs)

35. Rate of eGFR decline by diastolic BP at 6 months pre-RRT (adjusted for age, gender, ethnicity and PRD) (95% CIs)

36. Rate of eGFR decline pre-RRT by time from first presentation (adjusted for age, gender, ethnicity and PRD) (95% CIs)

37. Modelled eGFR pre-RRT by time from first renal presentation (adjusted for age, gender, ethnicity and PRD)

38. Discussion Limitations • Retrospective, only includes patients on RRT • Missing data • Date first seen, PRD, ethnicity, BP, co-morbidity • Timeline issues Strengths • Largest study of patients in the final year pre-RRT (4,722 vs. 159 & 342) • Unselected UK incident cohort • Jungers P, et al. NDT 1995; 10(8): 1353-60 [n=159] • Ambrogi V, et al. Nephron Clin Prac 2009; 111: 95-101 [n=342]

39. Summary of findings • Associations with faster eGFR decline are: • Younger age • Black and South Asian ethnicity • GN & diabetes • Higher systolic and diastolic BP • Late presentation

40. Acknowledgements Statistics Retha Steenkamp Supervisors Damian Fogarty, Yoav Ben-Shlomo, Charlie Tomson, David Ansell Data collection David Bull, Andy Webb and the UKRR systems team UK renal centres and patients