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Table 1 Demographics, Socioeconomic Status, and Behavioral Characteristics by Income Levels from NHANES III (1988–1994)

From: Income, inflammation and cancer mortality: a study of U.S. National Health and Nutrition Examination Survey mortality follow-up cohorts

Characteristics Total (N = 7817) Low Income (N = 3420) Middle Income (N = 3014) High Income (N = 1383) P-value
Age (years)      < 0.001a
 Median (Range) 53 (40–89) 58 (40–89) 53 (40–89) 51 (40–89)  
 Younger than 55 yrs 51.6% 40.7% 52.0% 61.0%  
 55 yrs. or older 48.4% 59.3% 48.0% 39.0%  
Race/Ethnicity      < 0.001a
 White 79.0% 64.1% 80.5% 90.5%  
 Black 9.8% 17.7% 8.7% 4.2%  
 Hispanics/Other 11.1% 18.2% 10.7% 5.3%  
Gender      < 0.001a
 Male 47.6% 42.3% 47.3% 52.8%  
 Female 52.4% 57.7% 52.7% 47.2%  
Education      < 0.001a
 Below High School 29.1% 55.6% 29.6% 14.8%  
 High School/Equivalent 32.5% 27.1% 36.6% 26.2%  
 Above High School 38.4% 7.9% 29.2% 62.9%  
Occupation      < 0.001a
 Not Working 2.8% 5.3% 2.4% 1.1%  
 White Collar and Professional 26.7% 11.7% 23.5% 45.0%  
 White Collar, Semi-Routine 22.8% 15.6% 23.7% 27.9%  
 Blue Collar, High Skill 13.3% 14.3% 15.1% 9.6%  
 Blue Collar, Semi-Routine 34.5% 53.1% 35.3% 16.4%  
Body Mass Index (kg/m2)      0.001a
 Median (Range) 26.6 (11.7–67.3) 27.3 (13.3–60.0) 26.5 (11.7–67.3) 25.9 (15.9–55.9)  
 Underweight 1.6% 2.2% 1.5% 1.0%  
 Normal 34.5% 31.3% 35.0% 36.6%  
 Overweight 37.1% 34.3% 37.2% 39.5%  
 Obese 26.9% 32.2% 26.4% 22.8%  
Smoking      < 0.001a
 Never 42.2% 41.8% 43.2% 41.0%  
 Former 33.9% 28.9% 33.4% 39.3%  
 Current 23.9% 29.4% 23.4% 19.7%  
Physical Activityb      < 0.001a
 More Active 37.7% 28.4% 37.9% 45.8%  
 Less Active 21.6% 27.8% 20.5% 17.5%  
 About Same 40.7% 43.8% 41.6% 36.7%  
C-Reactive Protein      < 0.001a
 Mean (Range) 0.45 (0.21–9.79) 0.57 (0.21–9.79) 0.43 (0.21–8.90) 0.38 (0.21–9.20)  
  < 0.22 mg/dL 66.1% 56.0% 67.9% 72.8%  
 0.22–0.99 mg/dL 24.7% 30.7% 23.7% 20.7%  
  > 0.99 mg/dL 9.2% 13.3% 8.4% 6.5%  
Fibrinogen      < 0.001c
 Mean (Range) 303 (19–957) 319 (30–928) 298 (19–957) 294 (85–806)  
  1. a Chi-Square tests were performed for categorical variables
  2. b Physical activity compared to others of the same age
  3. c t-tests were performed for the continuous variables