Dietary Approaches to Stop Hypertension - class presentation

Transcript

1. Diet  Blood Pressure Change a Randomized Clinical Trial Dietary Approaches to Stop Hypertension (DASH) Intisar Ghleilib Rafael Widjajahakim CI 790 Spring 2013
2. Blood Pressure (BP) • The force of blood pushing against the walls of arteries. • Measured indirectly with a special cuff over the brachial or femoral artery • There are two pressures measured: • the systolic pressure • the diastolic pressure Healthy individual: Systolic: <140 mmHg Diastolic <90 mmHg
3. Normal Blood Pressure Control sympathetic division of the autonomic nervous system and the kidneys.  blood volume  changes in diameter of arteries  speed and force the heart in pumping.
4. Hypertension (HTN) • The American Heart Association define the HTN as BP of 140/90 or higher. • It is a common disorder affect 24% of U.S. population.( 1997) • HTH is a systemic disease with no symptoms for years(silent killer). • It can be primary or essential ( 90- 95%) or secondary (5-10%).
5. Pathophysiology of HTN Overstretch vessels Weak vessels Tear &scars Block vessels Clot formation Stroke , heart attack,& end organ damage
6. Stages of HTN Classification Systolic mmHg Diastolic mmHg Normal <120 <80 Prehypertension 120-139 80-89 Stage 1 140-159 90-99 Stage 2 >160 >100
7. Risk factor of HTN • Over 45 years old • Overweight • African American • Family History • Eat a diet high in salt • Drink too much alcohol • Smoke While some of these risk factors can not change, but the others can change.
8. 1997 National Guide Line Recommendation to Decrease BP: • Weight control • Reduce intake of salt • Reduce alcohol consumption • Possible increase potassium intake
9. Food and BP • More salt intake lead to more thirsty  volume overload. • More K decrease BP and decrease stroke by 24%. • Fruits, vegetables, unprocessed meat and fish rich in K. • Processes food removes potassium and adds salt. • Fat intake cause obesity which stimulate adrenal aldosterone • Calcium decrease intestinal absorption of lipids.
10. Previous studies Observational Study • Vegetarians were observed to have lower BP • Inverse relationship of BP and the intake of Mg, K, Ca, fibers Clinical Trial • Trials for each Mg, K, Ca, fibers nutrients as supplements, results are inconsistent
11. Dietary Approaches to Stop Hypertension (DASH) • Started from 1993 • 1st group: Sept. 1994 • Funded by • NHLBI • Office of Research on Minority Health • National Center for Research Resources of the National Institutes of Health • Design: Clinical trial Clinical center : Baltimore Baton Rouge Durham Boston John Hopkins University Louisiana University Brigham and Women’s Hospital John Hopkins University Recruitment strategy - Mass mailing - Work-based - Community-based Targeted to have 2/3 participants as minority
12. DASH -the idea behind the design • Effects of a single molecule is hard to detect • Combining all nutrients = observable effects • Unknown nutrients/molecules • Unknown interactions • Natural > artificial The study also investigates the effects of the dietary interventions on changes in levels of serum lipids, renin, ionized and calcium. Also explores the effects of several baseline characteristics, Outcomes Ambu -latory Rest Systolic Diastolic Systolic Diastolic 1⁰ 2⁰ 2⁰ 2⁰ What is the effect of 3 different dietary pattern on the blood pressure in persons with high-normal and mild HTN? Study Question
13. Choice of Diets Control diets • Typical American diets • Follow average American diet composition • Keep K+, Mg++, and Ca++ similar (25th percentile) 37 48 15 Total Fat Carbohydrates Protein Combination diets • Rich in fruits and vegetables • Lower total fat and cholesterol composition • Higher fiber and protein • K+, Mg++, and Ca++ (75th percentile) 27 55 18 Total Fat Carbohydrates Protein Fruits and Vegetables diets • Primarily fruits and vegetables • Fat, carbohydrates and protein are similar to control • K+, Mg++, and Ca++ (75th percentile) 37 48 15 Total Fat Carbohydrates Protein
14. 37 35.7 37 35.7 27 25.6 16 14.1 16 12.7 6 7 13 12.4 13 13.9 13 9.9 8 6.2 8 7.3 8 6.8 48 50.5 48 49.2 55 56.5 15 13.8 15 15.1 18 17.9 0 10 20 30 40 50 60 Expected Found Expected Found Expected Found control Veggie Ideal Nutrients (% per Kcal) total fat saturated fat monounsaturated polyunsaturated Carbohydrates Protein
15. 1700 1752 4700 4101 4700 4415 165 176 500 423 500 480 450 443 450 534 1240 1265 3000 3028 3000 2816 3000 2859 EXPECTED FOUND EXPECTED FOUND EXPECTED FOUND CONTROL VEGGIE IDEAL Nutrients (mg/day) K⁺ Mg⁺⁺ Ca⁺⁺ Na⁺
16. Controlled feeding 4 Caloric levels • 1600 • 2100 • 2600 • 3100 7-day menu cycle (21 meals) Commonly available forms/variety • Fresh • Frozen • Canned • Dried Standardization: - Same brand - Prepared on the center kitchen Procedure: • On-site: lunch (weekdays) • Off-site: breakfast and dinner - provided with cooler and meal during visitation - Meals for weekend (received on Friday)  Recording beverages and salt intakes; non-study foods  Provided with 2 salt/day  Weight measured/weekday
17. Hypotheses and their inferences If Then Ideal > Veggie > Control Efficacy from all minerals + macronutrients from ideal diet (Ideal = Veggie) > Control Efficacy from minerals from fruits and vegetables Ideal > Control Veggie = X Efficacy from either  High Ca++ in dairy foods  Dairy food <-> fruits & vegetables  Macronutrients distribution of ideal diet Blood pressure lowering effect
18. 3 weeks 8 weeks 3 Visits (1 week in between) Within 4 mo. immediately Screened= 8813 Run-In= 502 Randomized= 459 Control= 154 147 Veggie= 154 150 Ideal= 151 149 Ineligible= 8311 Non-adhered= 43
19. Screening Age: ≥22 years • Not on anti HTN Medication. • Systolic BP: <160mm.Hg • Diastolic BP: 80- 95mm.Hg Exclusion criteria χ Unwillingness or inability to modify current diet. χ Significant morbidity. χ Uncontrolled DM or hyperlipidemia. χ cardiovascular event within previous 6 months χ Medication affecting BP χ Pregnancy and lactation. χ BMI > 35. χ Alcoholic-beverage intake > 14 drinks /wk. χ Renal insufficiency. N screened = 8813 Nstart run-in = 502
20. Screening Blood pressure measurement: 3 visitations - 1 week in between rest for 5 min. -Blood pressure (2x/visit) : - in seated position - by trained/certified staff - Random-zero sphygmomanometer -General dietary info -Stanford 7-Day Physical Activity Recall questionnaire Procedure:
21. Run-In Measurements <last 2 weeks>: • Blood pressure = 4 separate days • Urine sample = 1x 24-hour • Symptoms questionnaire Exclusionbefore randomization - Non adherence to the protocol (Fail to attend 1x on-site OR 3x meals) Participants were randomized at the 3rd week Duration = 3 weeks Control diet only N started = 502 Nrandomized = 459 Randomized
22. Sample population being randomized distribution 0 10 20 30 40 50 60 Control Veggie Ideal Age distribution 0% 50% 100% Control Veggie Ideal Sex distribution M F 0% 50% 100% Control Veggie Ideal Race distribution Nonminority Black other 0 50 100 150 Systolic Diastolic Systolic Diastolic Resting Ambulatory Blood pressure distribution Control Veggie Ideal
23. Duration = 8 weeks Control vs. Veggie vs. Ideal Total: N ITT = 459 NPP = 446 Intervention Measurement with staffs blinded • 1st 6 weeks: • Blood pressure (Rest) = 1x/wk • Last 2 wks: • Blood pressure = 5 separate days • Urine sample = 1x/24-hour • 1x questionnaire on symptoms • 1x Stanford 7-Day Physical Activity Recall questionnaire Begin: immediately after Run-In period
24. Duration = 8 weeks Control vs. Veggie vs. Ideal Total: N ITT = 459 NPP = 446 Intervention Measurement of ambulatory BP: - done only to the last 4/5 groups - At the end of Run-in & Intervention - Mean of 24-hour data/30-min interval - Space Labs 90207 device
25. Statistical analysis plan H0 = No difference between all diets 3 alternate hypothesis: 1. Ideal ≠ Control 2. Fruits & vegetables ≠ Control 3. Ideal ≠ Fruits & vegetables Power =85% ∆ =2 mm.Hg of Diastolic BP Analysis population: Statistical test: Statistical significance: Intention-to-treat 2-way ANOVA at P<0.025 (97.5% CI) Test (table 4): 1. ∆Ideal - ∆Control 2. ∆Fruits & vegetables - ∆Control 3. ∆Ideal - ∆Fruits & vegetables
26. -300 200 700 1200 1700 2200 2700 3200 Control Veggie Ideal Changes of excreted minerals -based on urine samples K⁺ Mg⁺⁺ Urea N⁺ Ca⁺⁺ P⁺⁺⁺ Na⁺
27. -250 -200 -150 -100 -50 0 50 100 150 Control Veggie Ideal Changes of excreted minerals - Mg, Ca, P, Na Mg⁺⁺ Ca⁺⁺ P⁺⁺⁺ Na⁺
28. -8 -7 -6 -5 -4 -3 -2 -1 0 1 Systolic Diastolic Systolic Diastolic Resting Ambulatory mmHg The change of BP between each dietary group I-C I-V V-C
29. 131.3 84.7 129.6 84.8 133 84.5 131.5 84.8 130.9 84.5 126.2 83 143.7 88.8 Systolic Diastolic Baseline BP of each subgroup HTN Non-HTN Non-minority Minority Female Male All -10 -8 -6 -4 -2 0 2 Systolic Diastolic Systolic Diastolic Male Female -10 -8 -6 -4 -2 0 2 Systolic Diastolic Systolic Diastolic Minority Non-minority -16 -14 -12 -10 -8 -6 -4 -2 0 2 Systolic Diastolic Systolic Diastolic HTN Non-HTN I-C I-V V-C
30. 120 122 124 126 128 130 132 Baseline 1 2 3 4 5 6 7&8 Systolic Control Systolic Veggie Systolic Ideal 74 76 78 80 82 84 86 88 Baseline 1 2 3 4 5 6 7&8 Diastolic Control Diastolic Veggie Diastolic Ideal Progress of BP changes for each diet -means of each week
31. Safety consideration Persons whose BP rise to levels necessitating referral are excluded from further participation if they are treated with medications. If BP: Systolic: > 170 mmHg Diastolic: > 105 mmHg OR Systolic: > 180 mmHg Diastolic: > 110 mmHg OR Rechecked: next visit (following week) Remain above limit: Physician referral Immediate referral
32. Conclusion • The most effective diet is rich in fruits, vegetable, low fat dairy, less saturated & total fat. • Ideal diet has similar effect of monotherapy used in mild HTN. • Applied for the prevention & treatment of HTN. • Ideal diet may reduce the occurrence of HTN-related cardiovascular diseases. Observation • Reduction of BP • started by 2nd week • But varied/increased around the last few weeks • Why smoking was not mentioned? • Unexpected Ca++ excretion on Veggie and Ideal diets
33. Strength • Multicenter and large number of subjects. • Provision of foods to the participants is intended to maximize adherence. • Blindness of BP observers and subjects. • Standardized protocol and centralized training of food service. • Same menus offered in all field centers (validated and monitoring). • 60% of subjects were black (high risk population).
34. Strength, cont. • Study the effect of the 3 different food pattern on the BP. • Meals available in 4 different energy levels according to the requirement to maintain the wt. • BP measured by same way and method by training staff in all center. • Assays related to study outcomes are measured in a central laboratory. • Subjects adherence to assigned diets was excellent. • Abstract is accurate. • Measurement of ambulatory BP add a confirmation of BP study measurement .
35. Limitation • the participants do have to make some life-style changes effort to accommodate the requirements of the study. Is it possible? • Procedure for evaluating of adherence (self report). • Trial was not design to identify the effective and ineffective component of diets. Limitation or strength?
36. Weakness • Generalizability. • No control of smoke. • 8 weeks intervention study is short period.
37. Future plan • Assess the affect of the diets on the BP > 8 weeks. • Assess the effect of the diets and cardiovascular diseases. • Assess the effect of the diet control on stage 2 HTN beside the medication. • DASH trial for non smoker.
38. Discussion after the study prove the effect of dietary pattern on BP, do you think the prevalence of HTN since 1997 is increase, decrease, or same?
40. Public health implication of trial results • Prevention of HTN • In HTN pts. Ideal diet alternative of the medication in stage 1 HTN. • Reduction of the occurrence of HTN-related cardiovascular disease by 15% and stroke by 27%
41. As 0f 2013 Based on NHLBI guideline: • Healthy diet • Lower Na+ and salts • Healthy weight • Physically active • Limit alcohol • Quit smoking Na+ Thank you for listening