Kidney function and aortic valve and mitral annular calcification in the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND: Aortic valve calcification (AVC) and mitral annular calcification (MAC) are highly prevalent and predictive of mortality in end-stage renal disease populations. Whether less severe kidney dysfunction is associated with AVC and MAC is uncertain. STUDY
DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: Ethnically diverse middle-aged adults without clinically apparent cardiovascular disease who participated in the Multi-Ethnic Study of Atherosclerosis. PREDICTOR: Estimated glomerular filtration rate (eGFR), cystatin C, and microalbuminuria. OUTCOMES & MEASUREMENTS: AVC and MAC were determined by means of computed tomography. Multivariable logistic regression evaluated the association of kidney function with AVC and MAC.
RESULTS: Of 6,785 participants, 10% had an eGFR less than 60 mL/min/1.73 m(2) (<1.0 mL/s/1.73 m(2)), mean cystatin C level was 0.9 +/- 0.2 mg/L, 7% had microalbuminuria (albumin >or= 30 mg/g), 15% had diabetes, 13% had AVC, and 9% had MAC. In adjusted analyses for AVC, eGFR less than 60 mL/min/1.73 m(2) (adjusted odds ratio, 1.23; 95% confidence interval, 0.99 to 1.14) and greater cystatin C concentrations (per SD increase; adjusted odds ratio, 1.06; 95% confidence interval, 0.99 to 1.14) had modest associations. Microalbuminuria was not associated independently with AVC (adjusted odds ratio, 1.11; 95% confidence interval, 0.89 to 1.40). For the MAC end point, associations of eGFR less than 60 mL/min/1.73 m(2) and greater cystatin C level differed by diabetes status (P for interaction = 0.1 and 0.02, respectively). In persons with diabetes, eGFR less than 60 mL/min/1.73 m(2) (adjusted odds ratio, 2.03; 95% confidence interval, 1.26 to 3.25) and greater cystatin C level (adjusted odds ratio, 1.38; 95% confidence interval, 1.14 to 1.68) were associated strongly, whereas no association was observed in subjects without diabetes (eGFR < 60 mL/min/1.73 m(2): adjusted odds ratio, 1.13; 95% confidence interval, 0.86 to 1.49; cystatin C: adjusted odds ratio, 1.03; 95% confidence interval, 0.93 to 1.13). The association of microalbuminuria with MAC (adjusted odds ratio, 1.37; 95% confidence interval, 1.06 to 1.76) did not differ by diabetes status (P for interaction = 0.2). LIMITATIONS: There were few participants with severe kidney disease.
CONCLUSIONS: Impaired kidney function had only a modest association with AVC, whereas its association with MAC was observed only in persons with diabetes. Future studies should evaluate whether associations of kidney impairment with dystrophic calcification differ by diabetes status in other clinical settings and vascular beds.