Variability and Risk Factors for Kidney Disease Progression and Death Following Attainment of Stage 4 CKD in a Referred Cohort

Background

The outcomes of patients referred to nephrologists are not well described in large cohorts. The objectives of this analysis are to describe the predictors of rapid progression of kidney disease and death in patients followed up by nephrologists.

Study Design

Retrospective study.

Setting & Participants

A cohort derived from all patients registered in the provincial database was formed that included all patients with index estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m², at least 3 subsequent eGFR values, and 4 months of follow-up between January 2000 and January 2004.

Predictors

Variables used to predict outcomes included baseline eGFR, duration of follow-up before eGFR less than 30 mL/min/1.73 m², age, sex, ethnicity, presence of diabetes, blood pressure, level of proteinuria, hemoglobin level, phosphate level, calcium level, parathyroid hormone level, and use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, erythropoiesis-stimulating agents, and vitamin D.

Outcomes

Key outcomes of interest were death, dialysis therapy start, or loss of GFR greater than 5 mL/min/1.73 m²/y.

Results

4,231 patients met inclusion criteria. Mean age was 67 years. Median follow-up was 31 months. During the first 2 years of follow-up, 24% started dialysis therapy, 1% received a transplant, 7% died, and 1% was lost to follow-up. Statistically significant variables associated with more rapid kidney disease progression differ from those that predict death. Younger age, male sex, higher eGFR, higher systolic and diabolic blood pressure, lower hemoglobin level, higher phosphorus and parathyroid hormone levels, and greater proteinuria are associated with more rapid kidney disease progression, and use of angiotensin-converting enzymes/angiotensin receptor blockers are protective. Older age, lower diastolic blood pressure, lower hemoglobin level, and higher phosphorous and parathyroid hormone levels are associated with death, whereas vitamin D use is protective.

Limitations

Results cannot be generalized to unreferred patients with eGFR less than 30 mL/min/1.73 m².

Conclusion

The clinical course of patients with chronic kidney disease stage 4 is variable. Targeted therapy aimed at modifiable risk factors needs to be evaluated to determine benefits of this approach.

Index Words: Progression, mortality, heterogeneity, chronic kidney disease (CKD), estimated glomerular filtration rate (eGFR)