Chronic Kidney Disease Stage and Cardiovascular and Mortality Events Among Older Adults: The SPRINT Trial

Rationale & Objective

The risk implications of the Kidney Disease: Improving Global Outcomes (KDIGO) chronic kidney disease classification in older adults are controversial. We evaluated the risk of adverse outcomes in this population across categories of estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR).

Study Design

Prospective cohort.

Settings & Participants

In total, 2,509 participants aged ≥75 years in the Systolic Blood Pressure Intervention Trial (SPRINT).

Exposure

KDIGO eGFR and UACR categories. We combined KDIGO categories G1 and G2, G3b and G4, as well as A2 and A3.

Outcomes

Primary SPRINT outcome (composite of myocardial infarction, other acute coronary syndromes, stroke, heart failure, or death from cardiovascular causes), and all-cause death.

Analytical Approach

Multivariable Cox proportional hazard models.

Results

Mean age was 79.8 years, and 37.4% were female. The mean eGFR was 64.0 mL/min/1.73 m², and the median UACR was 13.1 mg/g. In multivariable Cox proportional hazard analysis, compared with participants with eGFR ≥ 60 mL/min/1.73 m² and UACR < 30 mg/g, there was no statistically significant difference in the risk of the primary outcome among participants with eGFR 45-59 or 15-44 mL/min/1.73 m² and UACR < 30 mg/g. However, those with eGFR 45-59 or 15-44 mL/min/1.73 m² and UACR ≥ 30 mg/g had higher risk of the primary outcome (HR [95% CI], 1.97 [1.27-3.04] and 3.32 [2.23-4.93], respectively). The risk for all-cause death was higher for each category of abnormal eGFR and UACR, with the highest risk observed among those with eGFR 15-44 mL/min/1.73 m² and UACR ≥ 30 mg/g (3.34 [2.05-5.44]).

Limitations

Individuals with diabetes and urine protein >1 g/day were excluded from SPRINT.

Conclusion

Among older adults SPRINT participants, low eGFR without albuminuria was associated with higher mortality but not with increased risk of cardiovascular events. Additional studies are needed to evaluate an adapted chronic kidney disease stage-based risk stratification for older adults.

Plain-Language Summary

Using data from participants in the SPRINT trial, we evaluated the association of chronic kidney disease stage with adverse clinical outcomes among adults older than 75 years without diabetes. We found that low level of kidney function determined by a low estimated glomerular filtration rate with moderately or severely increased urine albumin excretion was associated with increased risk for cardiovascular events and all-cause mortality. However, low estimated glomerular filtration rate with normal or mildly increased urinary albumin excretion was not consistently associated with these adverse outcomes. This finding supports the need for additional studies to evaluate an age-adapted classification of chronic kidney disease to improve risk stratification among older adults.