Table 1.
Characteristics of study participants by dust endotoxin and serum vitamin D levels, NHANES 2005 – 2006 (N = 5,924)
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| Dust Endotoxin / Serum Vitamin D | Low / Normal | Low / Inadequate | High / Normal | High / Inadequate | P | All participants |
| Prevalence, % | 13.0 | 43.0 | 10.7 | 33.7 | 100 | |
| Age, median (IQR), years | 36 (22–54) | 41 (25–54) | 24 (8–46) | 35 (16–52) | 37 (20–53) | |
| Gender, % | ||||||
| Men | 45.9 | 49.8 | 51.7 | 48.1 | .22 | 48.9 |
| Women | 54.1 | 50.2 | 48.3 | 51.9 | 51.1 | |
| Race/ethnicity, % | < .001 | |||||
| Non-Hispanic Whites | 89.5 | 64.4 | 84.7 | 62.9 | 69.3 | |
| Non-Hispanic Blacks | 1.7 | 15.6 | 1.8 | 14.4 | 11.9 | |
| Hispanics | 5.0 | 12.4 | 8.2 | 16.7 | 11.9 | |
| Other | 3.8 | 7.6 | 5.3 | 6.0 | 6.3 | |
| BMI, % | < .001 | |||||
| Underweight | 10.6 | 7.3 | 27.7 | 13.3 | 11.9 | |
| Normal | 43.8 | 28.8 | 33.3 | 28.4 | 31.1 | |
| Overweight or obese | 43.4 | 62.5 | 34.9 | 55.9 | 54.9 | |
| Missing | 2.3 | 1.4 | 4.1 | 2.4 | 2.1 | |
| PIR, mean (SE) | 3.33 (0.13) | 3.01 (0.09) | 2.83 (0.13) | 2.51 (0.09) | < .001 | 2.86 (0.09) |
| Smoker in household, % | 18.9 | 17.8 | 23.0 | 23.0 | .06 | 20.2 |
| MET, mean (SE) | 17.43 (0.70) | 15.17 (0.26) | 25.60 (1.26) | 17.95 (0.61) | < .001 | 17.48 (0.29) |
| Years lived in house | ||||||
| <1 | 15.4 | 19.4 | 12.8 | 17.6 | .18 | 17.6 |
| 1 – 2 | 22.5 | 18.1 | 19.9 | 19.7 | 19.4 | |
| 3 – 5 | 17.7 | 18.4 | 20.1 | 19.9 | 19.0 | |
| 6 – 10 | 15.9 | 16.4 | 13.2 | 16.6 | 16.1 | |
| > 10 | 28.5 | 27.6 | 33.9 | 26.2 | 27.9 | |
| Mildew or musty smell in home, % | 17.5 | 15.8 | 16.8 | 17.3 | .86 | 16.6 |
| Cockroaches in home, % | 8.8 | 12.7 | 10.5 | 20.6 | < .001 | 14.6 |
| Pets in home, % | 58.4 | 44.5 | 64.9 | 55.3 | < .001 | 52.1 |
| Sensitization to aeroallergens, % | 39.0 | 44.5 | 33.8 | 40.8 | .001 | 41.4 |
| Asthma outcomes, % | ||||||
| Asthma diagnosis | 12.2 | 14.0 | 13.2 | 17.1 | .07 | 14.7 |
| Past asthma | 4.7 | 5.5 | 4.9 | 6.5 | .25 | 5.7 |
| Current asthma | 7.3 | 8.2 | 7.9 | 10.5 | .03 | 8.8 |
| Wheeze outcomes, % | ||||||
| Any wheeze | 13.0 | 15.9 | 14.4 | 19.4 | .002 | 16.5 |
| ≥ 2 wheezing episodes | 8.5 | 10.9 | 10.6 | 14.5 | < .001 | 11.8 |
| Combined wheeze and asthma, % | ||||||
| Recurrent wheeze & asthma diagnosis | 15.9 | 19.9 | 19.2 | 24.7 | .02 | 20.9 |
| Recurrent wheeze & current asthma | 12.4 | 15.0 | 14.4 | 19.1 | .02 | 16.0 |
Abbreviations: NHANES, National Health and Nutrition Examination Survey; IQR, Interquartile Range; SE, Standard Error; BMI, Body Mass Index; PIR, Poverty Income ratio; MET, Metabolic Equivalent Task. P-values indicate statistical significance of characteristics by exposure status. Low endotoxin is <19.1 EU/mg dust; normal serum vitamin D is ≥ 30 ng/ml.