Table 1.
Baseline Characteristics of the Study Population According to Socioeconomic Status, National Health and Nutrition Examination Survey, 2007–2008 and 2009–2010a
| Characteristic | Total (n = 9,823) |
Socioeconomic Statusb |
P Value | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Low (n = 3,289) |
Medium (n = 3,262) |
High (n = 3,272) |
|||||||
| % | Median (IQR) | % | Median (IQR) | % | Median (IQR) | % | Median (IQR) | ||
| Age, years | 49 (35–64) | 44 (31–61) | 51 (36–68) | 51 (38–63) | <0.001 | ||||
| Male sex | 49.0 | 44.5 | 49.9 | 52.7 | <0.001 | ||||
| Race/ethnicity | <0.001 | ||||||||
| Non-Hispanic white | 50.1 | 39.9 | 46.7 | 63.5 | |||||
| Non-Hispanic black | 18.0 | 17.9 | 20.2 | 15.9 | |||||
| Mexican-American | 17.2 | 24.2 | 18.8 | 8.5 | |||||
| Otherc | 14.7 | 17.9 | 14.3 | 12.1 | |||||
| Less than high school education | 35.1 | 55.1 | 34.2 | 10.8 | <0.001 | ||||
| Current smokingd | 22.1 | 32.9 | 19.1 | 14.3 | <0.001 | ||||
| High alcohol intakee | 20.4 | 26.3 | 21.1 | 14.7 | <0.001 | ||||
| Physical inactivityf | 53.4 | 67.3 | 57.8 | 41.2 | <0.001 | ||||
| Unhealthy dietg | 76.7 | 82.5 | 79.3 | 72.4 | <0.001 | ||||
| Sedentary time ≥4 hours/day | 32 | 41 | 33 | 24 | <0.001 | ||||
| Obesityh | 40.6 | 46.9 | 41.5 | 35.8 | <0.001 | ||||
| Abdominal obesityi | 51 | 58.7 | 51.9 | 40.5 | <0.001 | ||||
| Hypertension | 21.2 | 23.3 | 23.1 | 18.4 | <0.001 | ||||
| Diabetes mellitus | 14.6 | 17.4 | 15.1 | 11.5 | <0.001 | ||||
| Hypercholesterolemia, ≥6.2 mmol/L | 14.3 | 14.4 | 14.8 | 13.6 | 0.04 | ||||
| Health insurance | 23.5 | 39.3 | 23.9 | 7.3 | <0.001 | ||||
| No health-care visits in last year | 15.9 | 21.5 | 16.2 | 9.2 | <0.001 | ||||
| Serum creatinine level, mg/dL | 0.84 (0.72–1.01) | 0.82 (0.69–0.96) | 0.83 (0.72–1.02) | 0.88 (0.74–1.02) | 0.006 | ||||
| eGFR, mL/minute/1.73 m2 | 95.7 (78.4–111.1) | 92.6 (77.1–106.4) | 95.3 (75.5–111.6) | 101.5 (83.9–115.9 | <0.001 | ||||
| Low eGFR, <60 mL/minute/1.73 m2 | 9.2 | 8.7 | 7.7 | <0.001 | |||||
| Albumin:creatinine ratio, mg/g | 7.0 (4.5–13.6) | 7.7 (4.7–6.1) | 7.2 (4.5–14.4) | 6.3 (4.2–10.9) | <0.001 | ||||
| Moderate albuminuria, ≥30 mg/g | 12.1 | 13.1 | 9.2 | <0.001 | |||||
| Chronic kidney disease | 18.4 | 17.5 | 14.8 | <0.001 | |||||
Abbreviations: eGFR, estimated glomerular filtration rate; IQR, interquartile range.
a There was no significant difference in age and sex between the participants who were excluded because of missing income information and the final study participants.
b Socioeconomic status was defined as tertile of poverty income ratio (≤1.36 (low), 1.37–3.29 (middle), or 3.30–5.00 (high)). The poverty income ratio is calculated by dividing household income by the US federal poverty threshold.
c “Other” included other Hispanics as well as persons of other ethnicities, including multiracial individuals.
d Having smoked ≥100 cigarettes in one's lifetime and smoking every day or on some days of the week at the time of the interview.
e Having consumed ≥20 alcoholic drinks per month in the previous 12 months.
f Engaging in moderate-to-vigorous recreational physical activity less than 3 times per week.
g Consuming fruits or vegetables fewer than 5 times per week or reporting that fruits or vegetables were never or rarely available at home.
h Body mass index (weight (kg)/height (m)2) ≥30.
i Waist circumference ≥88 cm in women and ≥102 cm in men.