Nephrology consultation and kidney failure in people with stage 4 chronic kidney disease: a population-based cohort study

Background: Guidelines recommend referral for nephrology consultation for people with severe chronic kidney disease (CKD) to improve care and renal outcomes, yet the advocated benefits of nephrology referral on CKD progression in this patient population are unclear. Methods: We linked laboratory and administrative data in Alberta, Canada to identify adults with stage 4 CKD between 2002 and 2014 (follow-up end on March 31, 2017). We studied the association between time-varying receipt of outpatient nephrology consultation and kidney failure (the earlier of renal replacement initiation or eGFR < 10 mL/min/1.73 m2 for more than 3 months), accounting for the competing risk of death. Results: Of the 14,382 participants, 41% were ≥ 85 years old, 33% saw a nephrologist as an outpatient, 9% developed kidney failure, and 53% died over a median of 2.6 years. Compared with people who did not see a nephrologist before or at 7 months (median time to consultation), those who did were more likely to develop kidney failure [5-year risk (95% CI) 0.23 (0.21–0.24) vs 0.07 (0.065–0.075)]. With increasing age or higher eGFR, the 5-year risk of kidney failure became progressively smaller, from 0.24 (0.18–0.29) at age < 65 to 0.01 (0.006–0.015) at age ≥ 85 years and from 0.21 (0.18–0.23) at eGFR 15–19 to 0.066 (0.060–0.072) at eGFR 25–29 mL/min/1.73 m2; yet, the hazard ratio of kidney failure (1.6–4.3) increased following nephrology consultation in people who were older or had higher eGFR. Conclusions: Adults with stage 4 CKD who see a nephrologist are more likely to develop kidney failure than those who don’t, especially within lower absolute risk categories. Although selective referral may explain these findings, there is no evidence of an association between nephrology care and reduced risk of kidney failure in people with severe CKD. Studies are needed to assess the benefits of nephrology consultation in people with moderate CKD