Diet and Hypertension Management in African Americans With Chronic Kidney Disease

The purpose of this study is to determine cultural and disease-related barriers and facilitators to following the Dietary Approaches to Stop Hypertension (DASH) dietary pattern among Black Americans with moderate chronic kidney disease (CKD) and test the impact of a behavioral diet counseling intervention on DASH diet adherence, blood pressure, and CKD-relevant outcomes.

Excess cardiovascular disease (CVD) mortality among Black Americans with CKD is a significant US public health disparity. Compared to their White counterparts, Blacks develop CKD earlier in life and Blacks with CKD are 3 times more likely to progress to kidney failure necessitating dialysis or kidney transplantation, and are 1.5 times more likely to die prematurely from CVD. Hypertension, which is also more prevalent, more severe, and less often controlled in Blacks with CKD compared to Whites, is a leading cause of CKD and CVD, and a major contributor to the racial disparity in CVD mortality. Thus, improving hypertension in Blacks with CKD could have a profound positive impact on an important minority health issue. The DASH diet lowers BP and reduces CVD risk in patients with hypertension and has a greater effect on BP in Blacks compared to Whites. However, the effect of the DASH diet on BP in Blacks with CKD has not been established. First, investigators will conduct a qualitative study to identify self-perceived barriers and facilitators of DASH diet adherence among Blacks with moderate CKD. Then, investigators will conduct feasibility, acceptability, and preliminary efficacy testing of a disease-sensitive, culturally-appropriate diet counseling intervention on DASH adherence and blood pressure in Blacks with CKD. Prior to the clinical trial portion of this project Qualitative Focus Groups were held to identify self-perceived barriers and facilitators of DASH diet adherence among African Americans with CKD. Three to 4 groups of 6-8 participants were asked semi-structured questions to determine self-perceived sociocultural barriers and facilitators of DASH diet adherence and disease-specific factors that may influence their ability and willingness to follow a DASH-style diet. The information in the rest of this record pertains to the clinical trial portion of the project.

Groups of 4-6 participants will attend 12 weekly dietitian-led counseling sessions and receive coaching on practical strategies to enhance DASH diet adherence and reduce daily sodium intake.

Participants will meet one-on-one with the study dietitian for a single 30- minute encounter and be advised to limit daily sodium intake per current clinical practice guidelines for hypertension in patients with CKD. Educational handouts and tip sheets about practical strategies to reduce dietary sodium will be distributed.

Culturally-appropriate, disease-sensitive counseling intervention to enhance DASH diet adherence in Blacks with CKD compared to standard of care condition

Completion will be measured by the number of group counseling sessions attended by participants randomized to the treatment arm.

Completion will be measured by the number of randomized participants who provide blood and urine biospecimens, clinic and 24-hour ambulatory blood pressure measurements, and 24-hour dietary recall data during scheduled data collection visits at baseline, 1 month, 3 months, and 6 months.

Change will be measured by comparing the 24-hr mean systolic blood pressures (mmHg) obtained at baseline and at 12 weeks (end of treatment.)

Change will measured by comparing serum potassium concentration levels obtained at baseline and at 12 weeks (end of treatment.)

Change will be measured by comparing sodium concentration levels (mmol/24 hr) obtained from 24 hour urine samples collected at baseline and 12 weeks (end of treatment.)

Change will be measured by comparing potassium concentration levels (mmol/24 hr) obtained from 24 hour urine samples collected at baseline and 12 weeks (end of treatment.)

Change will be measured by comparing phosphorus concentration levels (mg/24 hr) obtained from 24 hour urine samples collected at baseline and 12 weeks (end of treatment.)

Change will be measured by comparing phosphorus concentration levels (g/24 hr) obtained from 24 hour urine samples collected at baseline and 12 weeks (end of treatment.)

Change will be measured by comparing clinic systolic blood pressures (mgHH) obtained at baseline and at 12 weeks (end of treatment.)

Change will be measured by comparing body weights (kg.) obtained at baseline and at 12 weeks (end of treatment.)

Change will be measured by comparing the 24-hour mean systolic blood pressures (mmHg) obtained at 12 weeks (end of treatment) and at 24 weeks (3-months post-treatment.)

Change will be measured by comparing body weights (kg.) obtained at 12 weeks (end of treatment) and at 24 weeks (3-months post-treatment.)

Number of participants who sustained their end of treatment DASH diet adherence scores for 3 months after intervention.

Sustained DASH diet scores will be measured by comparing scores derived from 24-hour dietary recall data obtained at 12 weeks (end of treatment) and at 24 weeks (3-months post-treatment.)

Inclusion Criteria: Black race (self-identified) ≥21 years old CKD defined as an eGFR of 30-59 ml/min/1.73m2 Exclusion Criteria: History of kidney transplant Pregnant of breast-feeding Risk factors for hyperkalemia including insulin-dependent diabetes mellitus, diabetes with poor blood glucose control (A1C >10), baseline serum potassium ≥4.8 mg/dl, and serum bicarbonate <18 mg/dl History of hypertension in the preceding 6 months defined as serum potassium greater than 5.1 mg/dl Risk for hypotension or severe hypertension (SBP <120 or ≥180 or DBP ≥110 mmHg) History of kidney transplant Lack of English language proficiency

Tyson CC, Davenport CA, Lin PH, Scialla JJ, Hall R, Diamantidis CJ, Lunyera J, Bhavsar N, Rebholz CM, Pendergast J, Boulware LE, Svetkey LP. DASH Diet and Blood Pressure Among Black Americans With and Without CKD: The Jackson Heart Study. Am J Hypertens. 2019 Sep 24;32(10):975-982. doi: 10.1093/ajh/hpz090.

Tyson CC, Barnhart H, Sapp S, Poon V, Lin PH, Svetkey LP. Ambulatory blood pressure in the dash diet trial: Effects of race and albuminuria. J Clin Hypertens (Greenwich). 2018 Feb;20(2):308-314. doi: 10.1111/jch.13170. Epub 2018 Jan 31.

Tyson CC, Lin PH, Corsino L, Batch BC, Allen J, Sapp S, Barnhart H, Nwankwo C, Burroughs J, Svetkey LP. Short-term effects of the DASH diet in adults with moderate chronic kidney disease: a pilot feeding study. Clin Kidney J. 2016 Aug;9(4):592-8. doi: 10.1093/ckj/sfw046. Epub 2016 Jun 5.

Tyson CC, Kuchibhatla M, Patel UD, Pun PH, Chang A, Nwankwo C, Joseph MA, Svetkey LP. Impact of Kidney Function on Effects of the Dietary Approaches to Stop Hypertension (Dash) Diet. J Hypertens (Los Angel). 2014;3:1000168. doi: 10.4172/2167-1095.1000168.