Table 1.
Associations of selected characteristics of the study population with FeNO*
| Year 1 | Year 2 | Mean FeNO (ppb) (95% CI) † | P-value‡ | |||
|---|---|---|---|---|---|---|
| N | % | N | % | |||
| Age (years) [mean (range)]§ | 2298 | 7.9 (6–10) | 2515 | 8.8 (7–11) | 34.9% (34.5%–35.2%) | <0.0001 |
| Sex | ||||||
| Girls | 1173 | 51.0 | 1283 | 51.0 | 12.66 (12.29, 13.05) | 0.61 |
| Boys | 1125 | 49.0 | 1232 | 49.0 | 12.53 (12.15, 12.91) | |
| Ethnicity | ||||||
| Non-Hispanic White | 905 | 39.4 | 975 | 38.8 | 11.99 (11.59, 12.41) | 0.0003 |
| Hispanic White | 1393 | 60.6 | 1540 | 61.2 | 12.99 (12.64, 13.35) | |
| Asthma | ||||||
| No | 2091 | 91.0 | 2200 | 87.5 | 12.16 (11.89, 12.44) | <0.0001 |
| Yes | 207 | 9.0 | 315 | 12.5 | 16.61 (15.63, 17.66) | |
| Respiratory allergy | ||||||
| No | 1101 | 47.9 | 1108 | 44.1 | 11.51 (11.16, 11.87) | <0.0001 |
| Yes | 1196 | 52.1 | 1405 | 55.9 | 13.60 (13.22, 14.00) | |
| Exposure to secondhand smoke | ||||||
| No | 2047 | 90.6 | 2244 | 89.6 | 12.54 (12.24, 12.84) | 0.08 |
| Yes | 212 | 9.4 | 259 | 10.4 | 13.37 (12.48, 14.34) | |
| BMI percentile | ||||||
| Underweight (<5th percentile) | 52 | 2.3 | 56 | 2.2 | 12.55 (11.13, 14.14) | 0.38 |
| Normal (5th to <85th percentile) | 1407 | 61.2 | 1543 | 61.4 | 12.70 (12.37, 13.04) | |
| Overweight (85th to<95th percentile) | 407 | 17.7 | 385 | 15.3 | 12.17 (11.63, 12.73) | |
| Obese (≥95th percentile) | 432 | 18.8 | 531 | 21.1 | 12.67 (12.12, 13.26) | |
| Respondent education | ||||||
| <12th grade | 475 | 21.6 | 516 | 21.5 | 13.59 (12.96, 14.24) | 0.0005 |
| 12th grade | 404 | 18.4 | 456 | 19.0 | 12.42 (11.80, 13.06) | |
| Some college | 838 | 38.1 | 908 | 37.7 | 12.68 (12.24, 13.14) | |
| College | 263 | 11.9 | 281 | 11.7 | 11.84 (11.11, 12.63) | |
| Some graduate | 221 | 10.0 | 244 | 10.1 | 11.54 (10.76, 12.38) | |
| Annual family income | ||||||
| <$15,500 | 297 | 15.0 | 320 | 14.9 | 13.49 (12.71, 14.31) | 0.003 |
| $15,000 – $49,999 | 663 | 33.4 | 708 | 33.0 | 12.86 (12.37, 13.38) | |
| ≥$50,000 | 1025 | 51.6 | 1119 | 52.1 | 12.11 (11.72, 12.50) | |
*
Sample included Hispanic and Non-Hispanic white children in the Children’s Health Study with available genetic and FeNO data, the latter collected between October 2004 and June 2005 (Year 1; N = 2298) and October 2005 and June 2006 (Year 2; N = 2515). Numbers do not always add up because of missing data.
†
Geometric mean and 95% CIs are obtained from a univariate repeated measure analysis of variance (PROC MIXED in SAS).
‡
P-values from repeated measure analysis of variance testing overall association of the variable with FeNO level.
§
For age (continuous), mean and range and percent difference in FeNO per year is presented with 95% CIs.