The Dietary Approaches to Stop Hypertension (DASH) diet score and its association with the Risk of Kidney Function Decline and Mortality among Veterans in the Million Veteran Program

Background: The dietary approaches to stop hypertension (DASH) diet is often recommended to patients with chronic kidney disease, although evidence regarding its efficacy in this population is limited. Our study tested the hypothesis that increased adherence to the dietary approaches to stop hypertension (DASH) diet score would be associated with longer time to kidney function decline among Veterans. Methods: We conducted a retrospective cohort study of 251,921 Veterans enrolled in the Million Veteran Program (MVP). The DASH diet score was calculated from the food frequency questionnaire and categorized into tertiles. The primary outcome was a composite of: Kidney event or death, where a kidney event was defined as a sustained 40% decline in estimated glomerular filtration rate (eGFR) or end-stage kidney disease (ESKD). Cox regression models compared the hazard for both outcomes by DASH score tertiles. We examined modification by ancestry, sex and other clinical characteristics Results: The median age was 67 years and 90% of Veterans were men. There were 59,269 (23.5%) who experienced the primary composite outcome, during the maximum follow-up of 10 years (median 6.1 years). Crude incidence rates for the kidney event and death outcome were 43.3, 40.4, and 36.8 per 1000 person-years of DASH score by tertiles. DASH score was associated with a lower hazard ratio (HR) for the primary composite outcome; third vs first tertile 0.81 (95% Confidence Interval (CI) 0.80 - 0.83) and second vs first tertile HR 0.90 [95% CI 0.88 - 0.92]. In subgroup analysis for individuals of African ancestry, Admixed American, and Females, only the third tertile of the DASH score was associated with a statistically significant reduction in composite outcome. Conclusion: Beneficial associations of the DASH diet were observed across subgroups. Future research is needed to understand gene and environmental factors that influence the observed subgroup differences