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

Background: The burden of chronic and end stage kidney disease (CKD and ESKD) is exceedingly high amongst American Indians (AI). We sought to examine the relationship of diet quality, a modifiable risk factor, and kidney outcomes in AI adolescents and young adults, hypothesizing that healthier diets are associated with lower odds of incident albuminuria and eGFR decline in this population.Methods: This is a secondary analysis of data 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=1721, mean age 39 +/- 16 years, 16% adolescents 14-21 years old, 61% female, 28% with hypertension, 13% with diabetes, 52% with obesity, 4% with CKD at baseline). Participants completed two exams (baseline: 2001-2003; follow-up: 2007-2009). The primary exposure (at baseline) was the Alternative Healthy Eating Index 2010 (AHEI), a measure of diet quality on a 110-point scale (assessed using a 119-item Block food frequency questionnaire). The primary outcomes (at follow-up) were: 1) incident albuminuria (albumin to creatinine ratio 30mg/g or greater); 2) eGFR decline of 30% or greater. Generalized estimating equations were used to examine the association of AHEI (in quartiles) with incident albuminuria and eGFR decline. Results: In total, 10% of participants (6% of adolescents) had incident albuminuria and 6% of participants (10% of adolescents) had eGFR decline of 30% or greater. Median AHEI for the least healthy diet quartile was 34 compared to 56 for the healthiest diet quartile. 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. Discussion: These results suggest an association of diet quality and incident albuminuria in AI with normal fasting glucose levels. Given the high burden of CKD in this population, further research is required to determine whether interventions to improve diet quality may improve kidney outcomes, particularly in those with normal fasting glucose levels such as adolescents and young adults.