Chronic kidney disease (CKD) is prevalent in older individuals, but the risk implications of low estimated glomerular filtration rate (eGFR) and high albuminuria across the full age range are controversial.
To evaluate possible effect modification (interaction) of age on the association of estimated GFR and albuminuria with clinical risk examining both relative and absolute risk.
Design, Setting, Participants
We investigated 2,051,244 participants from 33 general population or high-risk (of vascular disease) cohorts and 13 CKD cohorts from Asia, Australesia, Europe, and North/South America conducted during 1972–2011 with mean follow-up time of 5.8 years (range 0–31 years).
Main Outcome Measures
Hazard ratios (HRs) of mortality and end-stage renal disease (ESRD) according to eGFR and albuminuria were meta-analyzed across age categories after adjusting for sex, race, cardiovascular disease, diabetes, systolic blood pressure, cholestserol, body mass index, and smoking. Absolute risks were estimated using HRs and average incidence rates.
Mortality (112,325 deaths) and ESRD (8,411 events) risk were higher at lower eGFR and higher albuminuria in every age category. In general/high-risk cohorts, relative mortality risk for reduced eGFR decreased with increasing age: e.g., adjusted HRs (95% CI) at eGFR 45 vs. 80 ml/min/1.73m2 were 3.50 (2.55–4.81), 2.21 (2.02–2.41), 1.59 (1.42–1.77), and 1.35 (1.23–1.48) in age categories 18–54, 55–64, 65–74 and 75+ years, respectively (P-values for age interaction <0.05). Absolute risk differences for the same comparisons were higher at older age (9.0 [95% CI, 6.0–12.8], 12.2 [10.3–14.3], 13.3 [9.0–18.6], and 27.2 [13.5–45.5] excess deaths per 1,000 person-years, respectively). For increased albuminuria, reduction of relative risk with increasing age were less evident, while differences in absolute risk were higher in the older age categories (7.5 [95% CI, 4.3–11.9], 12.2 [7.9–17.6], 22.7 [15.3–31.6], and 34.3 [19.5–52.4] excess deaths per 1,000 person-years, respectively by age category, at ACR 300 mg/g compared to 10 mg/g). In CKD cohorts, adjusted relative hazards of mortality did not decrease with age. In all cohorts, ESRD relative risks and absolute risk differences at lower eGFR or higher albuminuria were comparable across age categories.
Both low eGFR and high albuminuria were independently associated with mortality and ESRD regardless of age across a wide range of populations. Mortality showed lower relative risk but higher absolute risks differences at older age.