Abdominal Obesity, Race and Chronic Kidney Disease in Young Adults: Results from NHANES 1999-2010

<div><p>Objective</p><p>Kidney dysfunction in obesity may be independent of and may precede the development of hypertension and/or diabetes mellitus. We aimed to examine if abdominal obesity is associated with early markers of CKD in a young healthy population and whether these associations differ by race and/or ethnicity.</p><p>Methods</p><p>We analyzed data from the NHANES 1999–2010 for 6918 young adults ages 20–40 years. Abdominal obesity was defined by gender criteria of waist circumference. CKD markers included estimated glomerular filtration rate and albuminuria ≥30 mg/g. Race stratified analyses were done overall and in subgroups with normal blood pressures, normoglycemia and normal insulin sensitivity. Awareness of CKD was assessed in participants with albuminuria.</p><p>Results</p><p>Abdominal obesity was present in over one-third of all young adults and was more prevalent among non-Hispanic blacks (45.4%) versus Mexican-Americans (40.6%) or non-Hispanic whites (37.4%) (P-value = 0.004). Mexican-American young adults with abdominal obesity had a higher odds of albuminuria even among those with normal blood pressure, normal glucose, and normal insulin sensitivity [adjusted odds ratio 4.5; 95% confidence interval (1.6–12.2), p = 0.004]. Less than 5% of young adults with albuminuria of all races and ethnicities had been told they had kidney disease.</p><p>Conclusion</p><p>Abdominal obesity in young adults, especially in Mexican-Americans, is independently associated with albuminuria even with normal blood pressures, normoglycemia and normal insulin levels. Greater awareness of CKD is needed to protect this young population from long-standing exposure to abdominal obesity and early progressive renal disease.</p></div

Association of Uremic Solutes with Outcomes among 394 Hemodialysis Participants of the CHOICE Study.

<p><i>Abbreviations</i>: HR, Hazard Ratio; CI, Confidence Interval.</p><p>Hazard ratio per 1 standard deviation increase in the solute level modeled using Cox proportional hazards regression.</p><p>¹ Model 1: Crude model without adjustment.</p><p>² Model 2: Minimally adjusted: HR adjusted for demographics (age, sex and race).</p><p>³ Model 3: Fully adjusted: HR adjusted for demographics (age, sex and race), clinical characteristics [body mass index, residual kidney function (self-reported ability to produce >1 cup of urine daily), Index of Coexistent Disease (ICED) score, diabetes and cardiovascular disease] and laboratory tests (Kt/V_UREA, albumin, phosphate and creatinine).</p><p>Note: Mean (Standard Deviation) for the free solutes are: P-cresol sulfate 0.196 (0.128) mg/dL; Indoxyl Sulfate 0.126 (0.100) mg/dL; Hippurate 1.5 (2.1) mg/dL and Phenylacetylglutamine 2.3 (1.7) mg/dL.</p><p>Association of Uremic Solutes with Outcomes among 394 Hemodialysis Participants of the CHOICE Study.</p

Association of Combined Solute Index Quintiles and Outcomes among 394 Hemodialysis Participants of the CHOICE Study.

<p><i>Abbreviations</i>: HR, Hazard Ratio; CI, Confidence Interval.</p><p>Hazard ratio per 1 standard deviation increase in the combined solute index in the continuous analysis modeled using Cox proportional hazards regression.</p><p>Note: Mean (Standard Deviation) for combined solute index is 5.5 (2.4).</p><p>¹ Model 1: Crude model without adjustment.</p><p>² Model 2: Minimally adjusted: HR adjusted for demographics (age, sex and race).</p><p>³ Model 3: Fully adjusted: HR adjusted for demographics (age, sex and race), clinical characteristics [body mass index, residual kidney function (self-reported ability to produce >1 cup of urine daily), Index of Coexistent Disease (ICED) score, diabetes and cardiovascular disease] and laboratory tests (Kt/V_UREA, albumin, phosphate and creatinine).</p><p>NOTE: Combined solute index is calculated as follows</p><p>¹⁾ Generate standardized value of each solute with a mean of 0 and standard deviation of 1.</p><p>²⁾ For each standardized solute create deciles based on percentiles of the data (range 1–10)</p><p>³⁾ Calculate the combined solute index by averaging the decile category for each participant</p><p>⁴⁾ Generate quintiles of the combined solute index. The lowest quintile is the reference.</p><p>Association of Combined Solute Index Quintiles and Outcomes among 394 Hemodialysis Participants of the CHOICE Study.</p

Adjusted Relative Hazard of Outcomes in 394 Incident Hemodialysis Patients of the CHOICE Study.

<p><b>Panel 2A:</b> Adjusted hazard of Cardiovascular Mortality. <b>Panel 2B:</b> Adjusted hazard of First Cardiovascular Event. Relative hazard predicted using Cox proportional hazards regression adjusted for demographics (age, sex and race), clinical characteristics [body mass index, residual kidney function (self-reported ability to produce >1 cup of urine daily), Index of Coexistent Disease (ICED) score, diabetes and cardiovascular disease] and laboratory tests (Kt/V_UREA, albumin, phosphate and creatinine). Solutes and combined solute index are modeled as restricted cubic splines with knots at the 10th, 50th, and 90th percentiles. The solid line is the adjusted HR; 10th percentile is used as the reference (HR = 1). The shaded area is the 95% CI of the HR. Bars are the frequency histogram, showing the distribution of each solute and combined solute index. Vertical broken lines mark the 25^th and 75^th percentile of the distribution.</p

Baseline Characteristics of 394 Hemodialysis Participants of the CHOICE Study.

<p>Note: Numbers presented are mean (standard deviation) or percent unless otherwise specified.</p><p>Conversion factors for units: albumin in g/dL to g/L, x 10; calcium in mg/dL to mmol/L, x 0.2495; phosphate in mg/dL to mmol/L, x 0.3229; hemoglobin in g/dL to g/L, x 10; BUN in mg/dL to urea in mmol/L, x 0.357; creatinine in mg/dL to μmol/L, x 88.4; p-cresol sulfate in mg/dL to μmol/L, x 53.1; indoxyl sulfate in mg/dL to μmol/L, x 46.9; hippuric acid in mg/dL to μmol/L, x 55.8; phenylacetylglutamine in mg/dL to μmol/L, x 37.8.</p><p>No conversion is necessary for potassium and bicarbonate in mEq/L to mmol/L.</p><p>Abbreviations: ICED: Index of Coexistent Disease Score; Kt/V: dialysis dose (K-dialyzer clearance of urea, t-dialysis time, V-volume of distribution of urea); CRP: C-Reactive Protein; IL-6: Interleukin 6</p><p>Baseline Characteristics of 394 Hemodialysis Participants of the CHOICE Study.</p

Correlations between Solutes in 394 Incident Hemodialysis Patients of the CHOICE Study.

<p>Scatterplots demonstrate the association between the solutes. Dots represent to concentrations of the two solutes on scatterplot. Line represents the linear fit between the two solutes. Spearman and Pearson correlation coefficients are also reported in a text box. P-values for all correlations were ≤0.001 for both Spearman and Pearson correlations.</p

Weighted baseline characteristics of CKD risk factors and CKD markers in young adults ages 20–40 years by race^¥.

<p>Weighted baseline characteristics of CKD risk factors and CKD markers in young adults ages 20–40 years by race<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0153588#t001fn001" target="_blank">^¥</a>.</p

Association between abdominal obesity and CKD risk Factors in White/Black and Mexican-American young adults 20–40 yrs^£.

<p>Association between abdominal obesity and CKD risk Factors in White/Black and Mexican-American young adults 20–40 yrs<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0153588#t002fn001" target="_blank">^£</a>.</p

Association of abdominal obesity with albuminuria among young adults 20–40 yrs with normal blood pressure and normoglycemia^£.

<p>Association of abdominal obesity with albuminuria among young adults 20–40 yrs with normal blood pressure and normoglycemia<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0153588#t003fn001" target="_blank">^£</a>.</p

Adjusted Effect Measures for the Association of Participant Characteristics with Year One Blood Creatinine Concentration Using Multiple Linear Regression (N = 1,500).

<p>Of N = 1,627 participants with year one creatinine available for analysis, 127 are not included due to missing data (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108094#pone-0108094-t001" target="_blank">Table 1</a>). CI, confidence interval.</p><p>Characteristics chosen for inclusion by backward elimination using the Akaike Information criterion for model selection, with race, Hispanic ethnicity and randomized vitamin D treatment group forced into the model; characteristics are from baseline, except diuretic use (see ²); results for study centers not shown.</p>1<p>Characteristics are modeled as continuous variables with units as shown.</p>2<p>Diuretic use between baseline and year one blood draws.</p>3<p>Change in creatinine (mg/dL) associated with the exposure (mean, coefficient).</p><p>Adjusted Effect Measures for the Association of Participant Characteristics with Year One Blood Creatinine Concentration Using Multiple Linear Regression (N = 1,500).</p