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Abstract: TH-PO1091

Referral to Nephrology Care and Mortality Risk in People with Stage 4 CKD: A Population-Based Study

Session Information

Category: CKD (Non-Dialysis)

  • 1901 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

  • Liu, Ping, University of Calgary, Calgary, Alberta, Canada
  • Quinn, Robert R., University of Calgary, Calgary, Alberta, Canada
  • Karim, Mohammad Ehsanul, University of British Columbia, Vancouver, British Columbia, Canada
  • Bello, Aminu K., University of Alberta, Edmonton, Alberta, Canada
  • Ronksley, Paul E., University of Calgary, Calgary, Alberta, Canada
  • Weaver, Robert G., University of Calgary, Calgary, Alberta, Canada
  • Tam-Tham, Helen, University of Calgary, Calgary, Alberta, Canada
  • Hemmelgarn, Brenda, University of Calgary, Calgary, Alberta, Canada
  • Manns, Braden J., Foothills Medical Center, Calgary, Alberta, Canada
  • Tonelli, Marcello, University of Calgary, Calgary, Alberta, Canada
  • Strippoli, Giovanni F.M., University of Bari, Bari, Italy
  • Ravani, Pietro, University of Calgary, Calgary, Alberta, Canada
Background

Guidelines recommend referral for specialist kidney care when estimated glomerular filtration rate (eGFR) is <30 ml/min/1.73m2 (stages 4-5 CKD). These recommendations are largely based on studies in people treated with dialysis showing 40% lower mortality with predialysis care of at least 4 months vs. shorter or no predialysis care. The effects of nephrology referral for the broader population of CKD patients are unknown. We examined the association between referral to nephrology care and mortality risk in people with stage 4 CKD.

Methods

Using population-based administrative and laboratory data, we identified all adults, residing in Alberta, with at least two consecutive outpatient measurements of eGFR ≥15 to <30 ml/min/1.73m2 spanning more than 90 days between 2002 and 2014. Patients were followed from date of the first eGFR after the 90-day qualifying period (study entry) until the earliest of death, out-migration from the province, or March 31, 2015. We used outpatient nephrology visit for at least once as a proxy for referral to nephrology care. We estimated hazard ratios (HRs) and confidence intervals (CIs) for all-cause mortality with nephrology referral (vs. no referral) and whether this effect varied by age, adjusting for baseline demographics and key laboratory and clinical characteristics, and using methods that address immortal time bias and time-varying confounding potentially affected by previous exposure status.

Results

Of the 15,315 study participants, 78% were ≥75 years old; 35% were referred to a nephrologist (median time-to-referral 8 months); and 67% died (median time-to-death 2.6 years). People who were referred were younger and had less comorbidity. Compared to non-referral, referral at any time during follow-up was independently associated with 12% lower mortality (HR 0.88; 95% CI, 0.83-0.93). The association was stronger in people aged <70 years (HR 0.80; 95% CI, 0.68-0.95) and absent in people aged ≥90 years (HR 1.05; 95% CI, 0.88-1.24).

Conclusion

Among people with stage 4 CKD meeting the criterion for nephrology referral, most of them are very old and the survival benefit of nephrology referral may be smaller than expected and become smaller with older age.

Funding

  • Government Support - Non-U.S.