Creatinine and Cystatin C eGFR Discordance in Relation to Metabolic Burden and Physical Impairment Across NHANES Surveys

This archive contains reproducibility materials for a cross-sectional investigation of creatinine–cystatin C estimated glomerular filtration rate discordance in relation to metabolic burden and physical impairment using publicly available National Health and Nutrition Examination Survey (NHANES) data. The primary analyses include NHANES 1999–2004, with objective gait-speed and quadriceps-force analyses restricted to 1999–2002. NHANES III (1988–1994) was analyzed separately as a historical comparison. Materials include analytic code, public NHANES source data files, derived analytic datasets, data-processing documentation, and statistical analysis outputs. Manuscript drafts and journal submission materials are excluded. The primary exposure is the cystatin C–based minus creatinine-based eGFR difference, expressed per 10 mL/min/1.73 m² lower difference. Original NHANES data were obtained from the US Centers for Disease Control and Prevention. Reproducibility materials are located in the “expanded” folder.