Browsing by Author "Tyson, Crystal C"
Now showing 1 - 9 of 9
Results Per Page
Sort Options
Item Open Access Apparent treatment-resistant hypertension and chronic kidney disease: another cardiovascular-renal syndrome?(Adv Chronic Kidney Dis, 2014-11) Vemulapalli, Sreekanth; Tyson, Crystal C; Svetkey, Laura PTo identify patients at increased risk of cardiovascular (CV) outcomes, apparent treatment-resistant hypertension (aTRH) is defined as having a blood pressure above goal despite the use of 3 or more antihypertensive therapies of different classes at maximally tolerated doses, ideally including a diuretic. Recent epidemiologic studies in selected populations estimated the prevalence of aTRH as 10% to 15% among patients with hypertension and that aTRH is associated with elevated risk of CV and renal outcomes. Additionally, aTRH and CKD are associated. Although the pathogenesis of aTRH is multifactorial, the kidney is believed to play a significant role. Increased volume expansion, aldosterone concentration, mineralocorticoid receptor activity, arterial stiffness, and sympathetic nervous system activity are central to the pathogenesis of aTRH and are targets of therapies. Although diuretics form the basis of therapy in aTRH, pathophysiologic and clinical data suggest an important role for aldosterone antagonism. Interventional techniques, such as renal denervation and carotid baroreceptor activation, modulate the sympathetic nervous system and are currently in phase III trials for the treatment of aTRH. These technologies are as yet unproven and have not been investigated in relationship to CV outcomes or in patients with CKD.Item Open Access Association of a reduction in central obesity and phosphorus intake with changes in urinary albumin excretion: The PREMIER study(American Journal of Kidney Diseases, 2013-11-01) Chang, Alex; Batch, Bryan C; McGuire, Heather L; Vollmer, William M; Svetkey, Laura P; Tyson, Crystal C; Sanguankeo, Anawin; Anderson, Cheryl; Houston, Jessica; Appel, Lawrence JBackground: Excess adiposity and dietary factors may be important determinants of urinary albumin excretion (UAE). Study Design: Observational analysis of PREMIER, a randomized trial designed to lower blood pressure using behavioral interventions (counseling on weight loss, healthy diet, and exercise). Setting & Participants: 481 participants with normal kidney function who provided adequate 24-hour urine collections at baseline and 6 months. Predictors: Change in waist circumference; 24-hour urine sodium, potassium, and phosphorus excretion; and protein intake estimated from urea nitrogen. Outcomes & Measurements: The primary outcome was change in log-transformed 24-hour UAE over 6 months. Results: After 6 months, the proportion of individuals with UAE ≥10 mg/d decreased from 18.7% to 12.7% (P < 0.001). Changes in mean waist circumference (-4.2 ± 6.6 [SD] cm), 24-hour excretion of sodium (-28.2 ± 71.7 mmol/d), potassium (+8.4 ± 27.8 mmol/d), phosphorus (-27.7 ± 314.1 mg/d), and protein intake (-1.7 ± 19.4 g/d) were observed. After adjustment for relevant covariates, the following variables were associated significantly with reduction in ln(UAE) in separate models: decrease in waist circumference (P = 0.001), decrease in 24-hour urine phosphorus excretion (P < 0.001), and decrease in protein intake (P = 0.01). In a multivariable model including these 3 predictors, decreases in waist circumference (P = 0.002) and 24-hour urine phosphorus excretion (P = 0.03), but not change in protein intake (P = 0.5), remained associated significantly with reduction in ln(UAE). These associations remained significant even after adjustment for changes in blood pressure and insulin resistance. Baseline UAE and metabolic syndrome modified the relationship of waist circumference with ln(UAE); specifically, individuals with higher UAE and baseline metabolic syndrome experienced greater reductions in ln(UAE) from decreases in waist circumference. Limitations: Observational study with potential for confounding. Conclusions: In adults with normal kidney function, decreases in waist circumference and 24-hour urine phosphorus excretion are associated with reductions in UAE. These findings support the rationale for clinical trials to determine whether reducing dietary phosphorus intake or waist circumference could prevent chronic kidney disease or slow its progression. © 2013 National Kidney Foundation, Inc.Item Open Access Cell phone intervention for you (CITY): A randomized, controlled trial of behavioral weight loss intervention for young adults using mobile technology.(Obesity (Silver Spring, Md.), 2015-11) Svetkey, Laura P; Batch, Bryan C; Lin, Pao-Hwa; Intille, Stephen S; Corsino, Leonor; Tyson, Crystal C; Bosworth, Hayden B; Grambow, Steven C; Voils, Corrine; Loria, Catherine; Gallis, John A; Schwager, Jenifer; Bennett, Gary GObjective
To determine the effect on weight of two mobile technology-based (mHealth) behavioral weight loss interventions in young adults.Methods
Randomized, controlled comparative effectiveness trial in 18- to 35-year-olds with BMI ≥ 25 kg/m(2) (overweight/obese), with participants randomized to 24 months of mHealth intervention delivered by interactive smartphone application on a cell phone (CP); personal coaching enhanced by smartphone self-monitoring (PC); or Control.Results
The 365 randomized participants had mean baseline BMI of 35 kg/m(2) . Final weight was measured in 86% of participants. CP was not superior to Control at any measurement point. PC participants lost significantly more weight than Controls at 6 months (net effect -1.92 kg [CI -3.17, -0.67], P = 0.003), but not at 12 and 24 months.Conclusions
Despite high intervention engagement and study retention, the inclusion of behavioral principles and tools in both interventions, and weight loss in all treatment groups, CP did not lead to weight loss, and PC did not lead to sustained weight loss relative to Control. Although mHealth solutions offer broad dissemination and scalability, the CITY results sound a cautionary note concerning intervention delivery by mobile applications. Effective intervention may require the efficiency of mobile technology, the social support and human interaction of personal coaching, and an adaptive approach to intervention design.Item Open Access Erratum: Cell phone intervention for you (CITY): A randomized, controlled trial of behavioral weight loss intervention for young adults using mobile technology.(Obesity (Silver Spring, Md.), 2016-02) Svetkey, Laura P; Batch, Bryan C; Lin, Pao-Hwa; Intille, Stephen S; Corsino, Leonor; Tyson, Crystal C; Bosworth, Hayden B; Grambow, Steven C; Voils, Corrine; Loria, Catherine; Gallis, John A; Schwager, Jenifer; Bennett, Gary GItem Open Access Impact of 5-year weight change on blood pressure: Results from the weight loss maintenance trial(Journal of Clinical Hypertension, 2013) Tyson, Crystal C; Appel, Lawrence J; Vollmer, William M; Jerome, Gerald J; Brantley, Phillip J; Hollis, Jack F; Stevens, Victor J; Ard, Jamy D; Patel, Uptal D; Svetkey, Laura PIn this secondary analysis of the Weight Loss Maintenance trial, the authors assessed the relationship between blood pressure (BP) change and weight change in overweight and obese adults with hypertension and/or dyslipidemia who were randomized to 1 of 3 weight loss maintenance strategies for 5 years. The participants were grouped (N=741) based on weight change from randomization to 60 months as: (1) weight loss, (2) weight stable, or (3) weight gain. A significant positive correlation between weight change and systolic BP (SBP) change at 12, 30, and 60 months and between weight change and diastolic BP (DBP) change at 30 months was observed. From randomization to 60 months, mean SBP increased to a similar degree for the weight gain group (4.2±standard error=0.6 mm Hg; P<.001) and weight stable group (4.6±1.1 mm Hg; P<.001), but SBP did not rise in the weight loss group (1.0±1.7 mm Hg, P=53). DBP was unchanged for all groups at 60 months. Although aging may have contributed to rise in BP at 60 months, it does not appear to fully account for observed BP changes. These results suggest that continued modest weight loss may be sufficient for long-term BP lowering. © 2013 Wiley Periodicals, Inc.Item Open Access Impact of Kidney Function on Effects of the Dietary Approaches to Stop Hypertension (Dash) Diet.(J Hypertens (Los Angel)) Tyson, Crystal C; Kuchibhatla, Maragatha; Patel, Uptal D; Pun, Patrick H; Chang, Alex; Nwankwo, Chinazo; Joseph, Michael A; Svetkey, Laura POBJECTIVES: Although the Dietary Approaches to Stop Hypertension (DASH) diet lowers blood pressure in adults with hypertension, how kidney function impacts this effect is not known. We evaluated whether Estimated Glomerular Filtration Rate (eGFR) modifies the effect of the DASH diet on blood pressure, markers of mineral metabolism, and markers of kidney function. METHODS: Secondary analysis of the DASH-Sodium trial, a multicenter, randomized, controlled human feeding study that evaluated the blood pressure lowering effect of the DASH diet at three levels of sodium intake. Data from 92 participants with pre-hypertension or stage 1 hypertension during the 3450 mg /day sodium diet assignment contributed to this analysis. Stored frozen plasma and urine specimens were used to measure kidney related laboratory outcomes. RESULTS: Effects of the DASH diet on blood pressure, phosphorus, intact parathyroid hormone, creatinine, and albuminuria were not modified by baseline eGFR (mean 84.5 ± 18.0 ml/min/1.73 m(2), range 44.1 to 138.6 ml/min/1.73 m(2)) or the presence of chronic kidney disease (N=13%). CONCLUSIONS: The impact of the DASH diet on blood pressure, markers of mineral metabolism, and markers of kidney function does not appear to be modified by eGFR in this small subset of DASH-Sodium trial participants with relatively preserved kidney function. Whether greater reduction in eGFR modifies the effects of DASH on kidney related measures is yet to be determined. A larger study in individuals with more advanced kidney disease is needed to establish the efficacy and safety of the DASH diet in this patient population.Item Open Access Retrospective cohort study of changes in estimated glomerular filtration rate for patients prescribed a low carb diet.(Current opinion in endocrinology, diabetes, and obesity, 2021-08-12) Mitchell, Nia S; Batch, Bryan C; Tyson, Crystal CPurpose of review
Obesity and diabetes contribute to chronic kidney disease (CKD) and accelerate the loss of kidney function. Low carbohydrate diets (LCDs) are associated with weight loss and improved diabetes control. Compared to the typical Western diet, LCDs contain more protein, so individuals with CKD are not included in studies of LCDs. Therefore, there are no studies of LCDs for weight loss and their effects on kidney function.Recent findings
Obesity, hyperglycemia, and hyperinsulinemia can be detrimental to kidney function. LCDs may improve kidney function in patients with obesity and diabetes because they are associated with weight loss, improve blood sugar control, and decrease endogenous insulin production and exogenous insulin requirements.Summary
In this study, for patients with mildly reduced and moderately to severely reduced kidney function who were prescribed an LCD, their estimated glomerular filtration rate (eGFR) was either unchanged or improved. For those with normal or elevated eGFR, their kidney function was slightly decreased. For those without diabetes, greater weight loss was associated with improved eGFR. Future studies should prospectively measure low carbohydrate dietary adherence and physical activity and directly measure changes in GFR and albuminuria for participants with CKD before and during that diet.Item Open Access Short-term effects of the DASH diet in adults with moderate chronic kidney disease: a pilot feeding study.(Clinical kidney journal, 2016-08) Tyson, Crystal C; Lin, Pao-Hwa; Corsino, Leonor; Batch, Bryan C; Allen, Jenifer; Sapp, Shelly; Barnhart, Huiman; Nwankwo, Chinazo; Burroughs, Jasmine; Svetkey, Laura PAlthough the Dietary Approaches to Stop Hypertension (DASH) diet lowers blood pressure (BP) for adults with normal kidney function, evidence is lacking regarding its safety and efficacy in chronic kidney disease (CKD). We aimed to test the effects of the DASH diet on serum electrolytes and BP in adults with moderate CKD.In a prospective before-after feeding study, 11 adults with an estimated glomerular filtration rate of 30-59 mL/min/1.73 m(2) and medication-treated hypertension were provided a reduced-sodium, run-in diet for 1 week followed by a reduced-sodium, DASH diet for 2 weeks. Changes in serum electrolytes and BP were compared pre-post DASH.Eleven participants underwent feeding; 1 completed 1 week and 10 completed 2 weeks of DASH. Compared with baseline, DASH modestly increased serum potassium at 1 week (mean ± standard deviation, +0.28 ± 0.4 mg/dL; P = 0.043) but had no significant effect on potassium at 2 weeks (+0.15 ± 0.28 mg/dL; P = 0.13). Serum bicarbonate was reduced (-2.5 ± 3.0 mg/dL; P = 0.03) at 2 weeks. Neither incident hyperkalemia nor new onset metabolic acidosis was observed. Clinic BP and mean 24-h ambulatory BP was unchanged. DASH significantly reduced mean nighttime BP (-5.3 ± 5.8 mmHg; P = 0.018), and enhanced percent declines in both nocturnal systolic BP (-2.1% to -5.1%; P = 0.004) and diastolic BP (-3.7% to -10.0%; P = 0.008).These pilot data suggest that a reduced-sodium DASH dietary pattern does not cause acute metabolic events in adults with moderate CKD and may improve nocturnal BP. Definitive studies are needed to determine long-term effects of DASH in CKD.Item Open Access The Dietary Approaches to Stop Hypertension (DASH) eating pattern in special populations.(Curr Hypertens Rep, 2012-10) Tyson, Crystal C; Nwankwo, Chinazo; Lin, Pao-Hwa; Svetkey, Laura PThe Dietary Approaches to Stop Hypertension (DASH) trial showed that a diet rich in fruits, vegetables, low-fat dairy products with reduced total and saturated fat, cholesterol, and sugar-sweetened products effectively lowers blood pressure in individuals with prehypertension and stage I hypertension. Limited evidence is available on the safety and efficacy of the DASH eating pattern in special patient populations that were excluded from the trial. Caution should be exercised before initiating the DASH diet in patients with chronic kidney disease, chronic liver disease, and those who are prescribed renin-angiotensin-aldosterone system antagonist, but these conditions are not strict contraindications to DASH. Modifications to the DASH diet may be necessary to facilitate its use in patients with chronic heart failure, uncontrolled diabetes mellitus type II, lactose intolerance, and celiac disease. In general, the DASH diet can be adopted by most patient populations and initiated simultaneously with medication therapy and other lifestyle interventions.