Chronic kidney disease defined by cystatin C predicts mobility disability and changes in gait speed: The Framingham Offspring Study

Abstract

Background: As creatinine-based estimates of renal function are inaccurate in older adults, an alternative is an estimated glomerular filtration rate (eGFRcys) based on cystatin C. We examined the prospective association between chronic kidney disease (CKDcys) as determined by eGFRcys with the primary outcome of incident mobility disability and the secondary outcome of change in gait speed. Methods: Framingham Offspring Study participants older than 60 years and free of mobility disability at baseline (1998-2001) were eligible. Baseline CKDcys was defined as eGFRcys less than 60 mL/min/1.73 m2. At follow-up (2005-2008), the outcomes of mobility disability, defined as self-reported inability to walk 1/2 mile and/or climb a flight of stairs, and gait speed were measured. Logistic and linear regression models were adjusted for age, sex, body mass index, smoking, diabetes, C reactive protein, and physical activity. Results: Of 1,226 participants, 230 (19%) had CKDcys at baseline. After a mean follow-up of 6.6 years, 185 (15%) developed mobility disability. Of those with CKDcys, 60 (26%) developed mobility disability. Those with CKDcys had greater odds of mobility disability in the age- and sex-adjusted (odds ratio [OR] 1.91, 95% CI 1.32, 2.75) and fully adjusted (OR 1.55, 95% CI 1.05, 2.31) models compared with those without CKDcys. In fully adjusted models, participants with CKDcys had greater gait speed declines than those without CKDcys (β = 0.07 [SE 0.02], p =.0022). Conclusion: CKDcys was associated with higher odds of incident mobility disability and greater decline in gait speed, highlighting the loss of physical independence in elders with CKD. © The Author 2013.