Table 1 Baseline characteristics of the study population.

From: The estimated mediating roles of anemia-related variables in the association between kidney function and mortality: a National Health and Nutrition Examination Survey (NHANES) study

Characteristic

Total (N = 44,099)

Anemia (N = 4727)

Age (years)

 20–45

19,965 (45.3)

1912 (40.4)

 46–64

13,360 (30.3)

1102 (23.3)

 64 or older

10,774 (24.4)

1713 (36.2)

Sex

 Male

21,288 (48.3)

1520 (32.2)

 Female

22,811 (51.7)

3207 (67.8)

Race/Hispanic origin

 Mexican American

8040 (18.2)

724 (15.3)

 Other Hispanic

3580 (8.1)

360 (7.6)

 Non-Hispanic White

20,152 (45.7)

1392 (29.4)

 Non-Hispanic Black

8773 (19.9)

1868 (39.5)

 Other race

3554 (8.1)

383 (8.1)

BMI (kg/m2)

 < 18.5

686 (1.6)

73 (1.5)

 18.5–25

12,310 (27.9)

1291 (27.3)

 25–30

14,811 (33.6)

1350 (28.6)

 30 or over

15,529 (35.2)

1840 (38.9)

Comorbidities

 Diabetes

6247 (14.2)

1135 (24.0)

 Hypertension

18,313 (41.5)

2441 (51.6)

Current smoking

 No

23,790 (53.9)

2909 (61.5)

 Yes

20,309 (46.1)

1818 (38.5)

Current drinking*

 Yes

28,471 (64.6)

2468 (52.2)

 No

12,081 (27.4)

1769 (37.4)

 Unknown

30 (0.1)

4 (0.1)

Laboratory tests

 Hemoglobin (Hb; g/dl)

14.1 (1.6)

11.4 (1.0)

 Hematocrit (Hct;%)

41.6 (4.4)

34.4 (2.9)

 Mean corpuscular hemoglobin (MCV; fL)

89.5 (5.8)

85.2 (9.4)

 Mean corpuscular hemoglobin (MCHC; pg)

30.4 (2.4)

28.4 (3.8)

 Albumin (g/dl)

4.2 (0.4)

3.9 (0.4)

 eGFR (ml/min/1.73 m2)

94.5 (23.2)

87.0 (32.1)

Family income to poverty ratio

2.5 (1.6)

2.2 (1.5)

Patients with anemia

4727 (10.7)

–

Patient with early CKD

15,645 (35.5)

4727 (21.2)

Patients with CKD

3614 (8.2)

1048 (22.2)

  1. The data are presented as the mean ± standard deviation or number (%). *Current drinking status was based on a questionnaire regarding the consumption of at least 12 alcoholic drinks per year.
  2. BMI body mass index, Egfr estimated glomerular filtration rate.
  3. Early CKD patients were grouped according to the following criteria: eGFR ≥ 90 ml/min/1.73 m2 and ACR ≥ 30 or 60 ≤ eGFR ≤ 90. CKD was defined as an eGFR ≤ 60 ml/min/1.73 m2 in this study. Anemia was defined as a Hb level less than 13.0 g/dl for men and 12.0 g/dl for women according to the World Health Organization (WHO) guidelines.
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