The Diet Gout Trial (DIGO)

Dietary Approaches to Stop Hypertension (DASH) Diet Effects on Serum Uric Acid (SUA) in Adults With Hyperuricemia and Gout

Massachusetts General Hospital, Beth Israel Deaconess Medical Center, Harvard Medical School (HMS and HSDM), Rheumatology Research Foundation

Unhealthy diet has long been associated with high uric acid levels and gout. The DASH diet may lower uric acid levels. This study will examine the effects of the DASH diet on uric acid in adults with a history of gout.

The public health burden of gout is substantial. Several lines of evidence suggest that a DASH diet might lower uric acid. However, there are no trials of the DASH diet in adults with gout. This trial is a cross-over study of the effects of a DASH-like diet on uric acid in adults with gout and hyperuricemia, who are not taking urate-lowering therapy. Perpetuated by the "Western" lifestyle and resulting obesity epidemic, the prevalence of gout has increased over the past few decades to 3.9% of US adults (8.3 million individuals). This prevalence increases with age to 9.3% of US adults over 60 years (4.7 million). Participants will be community-dwelling adults, aged 18+ with a baseline serum uric acid level of 7 mg/dL, who have a self-reported history of gout and are not taking urate lowering medications (e.g. allopurinol, febuxostat, probenecid). This trial is comprised of two study periods: (1) a dietitian-directed diet (DD) or (2) self-directed usual diet (SD). Each period lasts 4 weeks. All participants will participate in both periods, but half will undergo the dietitian-directed diet first while the other half will undergo the self-directed diet first. During the dietitian-directed diet, participants will receive $105/week of foods in a pattern that conforms to the DASH diet. The DASH diet emphasizes fruit, vegetables, lean meat, low fat dairy, and high fiber, while restricting red meat, sweets, and sugary beverages. During the self-directed diet, participants will be asked to eat their typical diet outside of the study. Investigators anticipate 40 participants in this study. The primary outcome is uric acid. Secondary outcomes of this study include: body mass index, systolic and diastolic blood pressure, fasting cholesterol, and fasting blood glucose. Both primary and secondary outcomes will be measured 3 times: (1) before the study begins (baseline), (2) after period 1 (at 4 weeks), and (3) after period 2 (at 8 weeks). Patient-reported outcomes, dietary compliance, and urine electrolytes will be assessed throughout the study as well. The primary comparison will be serum uric acid concentrations measured after the 4-week dietitian-directed diet versus uric acid concentrations measured after the 4-week self-directed diet (DD vs. SD). Comparisons will be made within person using generalized estimating equations (GEE) with and without adjustment for baseline uric acid concentration. Investigators will use GEE models for secondary outcomes as well.

Diet, Nutrition, DASH, Gout, Hyperuricemia, Potassium, Uric acid, Trial, Blood pressure, Glucose, Lipid, Cholesterol, Weight, Arthritis, BMI, Body mass index, Fruit, Vegetable, Low fat dairy, Lean meat, Fiber

Half of participants will be randomly assigned 1 of 2 potential sequences. All participants will ultimately participate in each study period, but the order will be randomly assigned 1:1.

Investigators will not know which assignment the participants were given. The laboratory measuring uric acid will not know which intervention the participants were assigned.

Participants will be provided $105/week ($15/day) to purchase foods in servings that correspond to the DASH diet and thus include fruits, vegetables, lean meat, low fat dairy, and high fiber foods. Participants will also be asked to restrict red meat, sweets, and sugary beverages during this intervention period. A dietitian will help participants order foods from a digital supermarket. Foods will be delivered to the Johns Hopkins ProHealth Research Clinic for weekly pick-up. This study period will last 4 weeks.

Participants will be asked to consume their typical diet for 4 weeks. There will be no subsidy during this period.

$105/wk of DASH-like foods over 4 weeks purchased with the help of a dietitian in a proportion that reflects the DASH diet.

Inclusion Criteria: Age > 18-100 years Self-reported gout diagnosis Serum Uric Acid > 7 mg/dL Exclusion Criteria: Recent or planned changes to urate lowering therapies (e.g. allopurinol, febuxostat, probenecid) Recent or planned changes to hypertension, lipid, or diabetes medications Patients with hyperkalemia (>5 mmol/L) Chronic kidney disease (GFR < 30 cc/min), kidney transplant, dialysis Gastro-intestinal conditions (e.g. history of gastric bypass surgery, active inflammatory bowel disease, malabsorption, or major GI resection) Active cancer treatment (e.g. radiation or chemotherapy) Diagnosis of any of the following in the past 6 months: heart attack, heart failure, angina, coronary bypass or angioplasty, or Chronic Obstructive Pulmonary Disease (COPD) Alcohol use over 14 drinks per week Inability to give informed consent Active use of warfarin, insulin, or chronic steroids (like prednisone) Terminal or mental illness

Ghazi L, Drawz PE, Pajewski NM, Juraschek SP. The Association of Orthostatic Hypotension With Ambulatory Blood Pressure Phenotypes in SPRINT. Am J Hypertens. 2021 May 22;34(5):511-520. doi: 10.1093/ajh/hpaa184.

Miller HN, Charleston J, Wu B, Gleason K, White K, Dennison Himmelfarb CR, Ford DE, Plante TB, Gelber AC, Appel LJ, Miller ER 3rd, Juraschek SP. Use of electronic recruitment methods in a clinical trial of adults with gout. Clin Trials. 2021 Feb;18(1):92-103. doi: 10.1177/1740774520956969. Epub 2020 Sep 15.