The relationship between kidney function and quality of life among community-dwelling adults varies by age and filtration marker.

Background: The impact of a diminished level of kidney function on the well-being of an older individual is poorly understood. We sought to determine the association between estimated glomerular filtration rate (eGFR) and overall quality of life (QoL) among older adults.

Methods: Cross-sectional analysis of 4293 participants from the Irish Longitudinal Study on Ageing, a population-based study of community-dwelling adults ≥50 years of age. We used multivariable negative binomial regression to model the relationship between categories of cystatin C eGFR (eGFRcys ) or creatinine eGFR (eGFRcr ) and the number of QoL deficits from the Control, Autonomy, Self-realization and Pleasure (CASP-19) scale, a holistic measure of QoL among older adults (range 0-57). We further explored this relationship across age strata.

Results: Median age was 61 [interquartile range (IQR) 55-68] years, 53% were female, mean (SD) CASP-19 score was 44.8 (7.4) and median eGFRcys was 81 (IQR 68-93) mL/min/1.73 m2 . After multivariable adjustment, participants with eGFRcys <45 mL/min/1.73 m2 had 14% greater QoL deficits {incidence rate ratio 1.14 (95% confidence interval 1.03-1.25)] relative to the reference group (eGFRcys ≥90 mL/min/1.73 m2 ). This relationship appeared linear across eGFRcys categories and was more pronounced in younger (50-64 years) compared with older participants (65-74 or ≥75 years). There was no substantive relationship between eGFRcr and CASP-19.

Conclusions: Cystatin C but not creatinine eGFR was associated with clinically modest declines in QoL among a large sample of community-dwelling older adults. This relationship varied by age, suggesting that a diminished eGFR contributes little to overall QoL beyond middle age in this population.