Abstract: FR-PO913

Kidney Function Is Not Associated with an Accelerated Decline in Objective Tests of Physical Performance in Older Adults

Session Information

  • Geriatric Nephrology
    November 03, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Geriatric Nephrology

  • 901 Geriatric Nephrology

Authors

  • Canney, Mark, Trinity College Dublin, Dublin, Ireland
  • Carey, Daniel, Trinity College Dublin, Dublin, Ireland
  • Kenny, Rose Anne M., Trinity College Dublin, Dublin, Ireland
  • Little, Mark Alan, Trinity College Dublin, Dublin, Ireland
  • O'Seaghdha, Conall M., Beaumont Hospital, Dublin, Ireland
Background

Cross-sectional studies in older adults have identified an association between diminished estimated glomerular filtration rate (eGFR) and frailty. Whether kidney function is driving frailty, or both conditions have shared risk factors, is not well understood. Longitudinal studies could inform this question. We sought to examine whether baseline eGFR predicted an accelerated decline in gait speed or timed-up-and-go (TUG) in a large representative sample of older adults.

Methods

Prospective analysis from the first 3 waves (2009-2015) of The Irish Longitudinal Study on Ageing, a nationally representative cohort of community-based adults aged ≥50 years. Gait speed was measured at waves 1 and 3 in 3140 participants (mean age 60.9 years). TUG was measured at all 3 waves in 4930 participants (mean age 62.6 years). We calculated eGFR at wave 1 from cystatin C using the Chronic Kidney Disease Epidemiology equation. We used mixed effects linear regression to examine the association between categorical eGFR (>90, 60-89, <60mL/min/1.73m2) and each outcome. Models were adjusted for age, sex, height, waist circumference, smoking, diabetes, pulse pressure, cardiovascular disease, polypharmacy, chronic health conditions. Each covariate was included as a main effect and its interaction with time (wave). The parameter of interest was the time*eGFR interaction. Analyses were weighted to account for differential non-response and attrition across waves.

Results

For gait speed the unadjusted time*eGFR interaction was strongly statistically significant (p<0.001) but did not retain significance after adjustment for age, sex and comorbidites (p=0.22). A similar pattern was observed for TUG: p<0.001 for unadjusted interaction, p=0.43 for multivariable-adjusted interaction. In a subgroup analysis, participants with eGFR<50mL/min/1.73m2 (the median eGFR in the <60mL/min/1.73m2 category) had some evidence of worse TUG over time compared to those with eGFR>60mL/min/1.73m2, however the effect size was modest (0.3 seconds longer).

Conclusion

In this large cohort of older adults, a diminished eGFR did not predict an accelerated decline in objectively measured tests of physical performance. The strong association between eGFR and markers of frailty may be best explained by comorbidity rather than reduced kidney function per se.

Funding

  • Government Support - Non-U.S.