Kidney Function and Fracture Risk: The Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND: People with end-stage renal disease are at high risk for bone fracture. Less is known about fracture risk in milder chronic kidney disease and whether chronic kidney disease-associated fracture risk varies by sex or assessment with alternative kidney markers.

STUDY DESIGN: Prospective cohort study.

SETTING & PARTICIPANTS: 10,955 participants from the Atherosclerosis Risk in Communities (ARIC) Study followed up from 1996 to 2011.

PREDICTOR: Kidney function as assessed by creatinine-based estimated glomerular filtration rate (eGFRcr), urine albumin-creatinine ratio, and alternative filtration markers.

OUTCOMES: Fracture-related hospitalizations determined by diagnostic code.

MEASUREMENTS: Baseline kidney markers; hospitalizations identified by self-report during annual telephone contact and active surveillance of local hospital discharge lists.

RESULTS: Mean age of participants was 63 years, 56% were women, and 22% were black. During a median follow-up of 13 years, there were 722 incident fracture-related hospitalizations. Older age, female sex, and white race were associated with higher risk for fracture (P<0.001). The relationship between eGFRcr and fracture risk was nonlinear: <60mL/min/1.73m(2), lower eGFRcr was associated with higher fracture risk (adjusted HR per 10mL/min/1.73m(2) lower, 1.24; 95% CI, 1.05-1.47); there was no statistically significant association for ≥60mL/min/1.73m(2) in the primary analysis. In contrast, there was a graded association between other markers of kidney function and subsequent fracture, including albumin-creatinine ratio (HR per doubling, 1.10; 95% CI, 1.06-1.14), cystatin C-based eGFR (HR per 1-SD decrease, 1.15; 95% CI, 1.06-1.25), and 1/β2-microglobulin (HR per 1-SD decrease, 1.26, 95% CI, 1.15-1.37).

LIMITATIONS: No bone mineral density assessment; one-time measurement of kidney function.

CONCLUSIONS: Both low eGFR and higher albuminuria were significant risk factors for fracture in this community-based population. The shape of the association in the upper ranges of eGFR varied by the filtration marker used in estimation.