Table 4.
Baseline Characteristics of National Health and Nutrition Examination Survey (NHANES) III Participants with Chronic Kidney Disease Stages 3 or 4 [Defined using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation], Overall and by Race/Ethnicity
| Characteristic | All (n=991) % |
Non-Hispanic Blacks (n=309) % |
Non-Hispanic Whites (n=682) % |
P-value |
|---|---|---|---|---|
| Mean age in years (SD) | 73.2 (11.8) | 67.7 (12.7) | 74.5 (11.2) | 0.03 |
| 20-50 | 4.0 | 6.7 | 3.3 | |
| 50-70 | 27.5 | 48.8 | 22.2 | |
| >70 | 68.5 | 44.5 | 74.5 | |
| Male sex | 42.9 | 46.3 | 42.0 | 0.27 |
| Poverty Income Ratio | <0.0001 | |||
| <=1 | 17.1 | 39.6 | 11.5 | |
| 1-2 | 32.2 | 29.3 | 32.9 | |
| 2-3 | 19.8 | 15.2 | 20.9 | |
| 3-4 | 14.0 | 9.8 | 15.0 | |
| >4 | 16.9 | 6.1 | 19.6 | |
| Education | <0.0001 | |||
| <High School | 50.6 | 67.8 | 46.4 | |
| Some College | 37.4 | 27.3 | 39.9 | |
| >College | 12.0 | 5.0 | 13.7 | |
| Diabetes (yes) | 18.0 | 32.9 | 14.3 | 0.0001 |
| Hypertension (yes) | 80.4 | 88.4 | 78.5 | 0.003 |
| Estimated GFR, median in ml/min per 1.73m2 (IQR) | 47.3 (41.6-55.5) | 50.2 (41.1-55.2) | 50.8 (44.5-55.6) | 0.04 |
| Albuminuria (>30 mg/gm) | 29.9 | 45.1 | 26.1 | <0.0001 |
| Total Calories >2000 Kcal/day | 21.7 | 16.5 | 23.1 | 0.09 |
| Net Acid Excretion, median in mEq/day (IQR) | 47.3 (41.6-53.6) | 47.4 (41.2-52.9) | 47.2 (41.7-53.8) | 0.67 |
*
CKD-EPI equation was used in sensitivity analysis to define chronic kidney disease, given its reported greater precision over the Modification of Diet in Renal Disease study equations51. Poverty income ratio is the ratio of family income to poverty threshold. Hypertension was defined by self-report, average systolic blood pressure >140 or average diastolic blood pressure >90 mmHg, or use of medication.