Diet Quality and Kidney Outcomes in Adolescent and Adult American Indians: the Strong Heart Family Study.

Background: The burden of kidney disease is exceedingly high among American Indians (AIs). We sought to examine the relationship of diet quality, a modifiable risk factor, and kidney outcomes in AI adolescents and adults, hypothesizing that healthier diets are associated with lower odds of incident albuminuria and eGFR decline.

Methods: This is an analysis from the Strong Heart Family Study, a longitudinal study of cardiovascular disease and its risk factors among AIs from Arizona, North and South Dakota, and Oklahoma (n = 1720, mean age 39 + / - 16 years, 16% adolescents at baseline). Participants completed two exams (baseline: 2001-2003; follow-up: 2007-2009). The primary exposure was diet quality, expressed as the Alternative Healthy Eating Index 2010 (AHEI), on a 110-point scale (assessed using a 119-item Block food frequency questionnaire). The primary outcomes were as follows: 1) incident albuminuria (albumin to creatinine ratio 30 mg/g or greater); and 2) eGFR decline of 30% or greater. Generalized estimating equations were used to examine the association of AHEI (in quartiles) with outcomes.

Results: Ten percent of participants (6% of adolescents) had incident albuminuria and 2% of participants (2% of adolescents) had eGFR decline. For those with normal fasting glucose levels, the odds ratio (OR) for incident albuminuria comparing extreme quartiles of diet quality (least healthy [reference] versus healthiest quartiles) was 0.48 (95% CI 0.28, 0.81) after adjustment for demographics and comorbidities.

Conclusions: For American Indians with normal fasting glucose, higher diet quality decreases the odds of developing albuminuria. These findings inform future efforts to prevent CKD in American Indian adolescents and young adults.