Predicting survival of older community-dwelling individuals according to five estimated glomerular filtration rate equations: The InChianti study.

AIMS: There is uncertainty about which estimated glomerular filtration rate eGFR equation to use in older people with respect to the prediction of prognosis. Our aim was: (i) to compare the discriminative capacity of eGFR estimated by different equations with respect to all-cause mortality; and (ii) to identify the eGFR threshold at which the risk of mortality starts to increase for each equation.

METHODS: We used data from 828 community-dwelling older adults aged >65 years enrolled in the InCHIANTI study. The outcome measure was all-cause mortality at 9 years. GFR was estimated by five different equations: Chronic Kidney Disease Epidemiological Collaboration (creatinine equation [CKD-EPIcre ], and creatinine and cystatin C equation [CKD-EPIcre-cys ]), Berlin Initiative Study (BIScre and BIScre-cys ) and full age spectrum. Sensitivity, specificity, areas under receiver operating curve (AUC) and C-statistics were used to compare their predictive capacity.

RESULTS: The best mix of sensitivity, specificity, AUC and C-statistic value in predicting mortality was observed with BIS equations. BIScre (AUC 0.65, 95% CI 0.61-0.69) outperformed both CKD-EPIcre (AUC 0.60, 95% CI 0.56-0.64; P = 0.005) and full age spectrum (AUC 0.63, 95% CI 0.59-0.67; P = 0.002) in terms of predictivity. Similarly, BIScre-cys (AUC 0.67, 95% CI 0.63-0.71) outperformed CKD-EPIcre-cys (AUC 0.63, 95% CI 0.59-0.67; P = 0.01). AUC obtained with equations also including cystatin C were not significantly different compared with their creatinine-based counterparts. The risk of long-term mortality began to increase at under 65.6 mL/min/1.73 m2 for CKD-EPIcre-cys , 60.5 for CKD-EPIcre , 60 for BIScre-cys , 56.3 for BIScre and 55.2 for full age spectrum.

CONCLUSIONS: The BIS equation discriminates the risk of all-cause mortality better than other equations in older community-dwelling individuals. The eGFR threshold under which mortality starts to increase could change as a function of the equation used. Geriatr Gerontol Int 2018; 18: 607-614.