TABLE 2.
LONGITUDINAL RANDOM EFFECTS MODELS OF LUNG FUNCTION AT AGES 11 AND 16 yr FOR PRESCHOOL WHEEZE PHENOTYPES, CURRENT WHEEZE, AND SEX*
| FEF25–75 (ml/s)
|
FEV1 (ml)
|
FEV1:FVC Ratio (%)
|
||||
|---|---|---|---|---|---|---|
| Coefficient§ (95% CI) | p Value | Coefficient§ (95% CI) | p Value | Coefficient§ (95% CI) | p Value | |
| Preschool wheeze phenotype† | ||||||
| Never wheeze | Ref | — | Ref | — | Ref | — |
| Transient early wheeze | −259 (−392 to −127) | < 0.001 | −75 (−139 to −11) | 0.02 | −1.9 (−3.1 to −0.7) | 0.002 |
| Late-onset wheeze | −99 (−248 to 50) | 0.2 | −23 (−95 to 49) | 0.5 | −0.8 (−2.2 to 0.5) | 0.2 |
| Persistent wheeze | −260 (−419 to −101) | 0.001 | −87 (−164 to −9.4) | 0.03 | −2.5 (−3.9 to −1.0) | 0.001 |
| Current wheeze‡ | ||||||
| No wheeze | Ref | — | Ref | — | Ref | — |
| Infrequent | −69 (−171 to 34) | 0.2 | −66 (−120 to −12) | 0.02 | 0.03 (−0.9 to 0.9) | 0.9 |
| Frequent | −341 (−492 to −191) | < 0.001 | −136 (−215 to −58) | 0.001 | −2.8 (−4.1 to −1.5) | < 0.001 |
| Sex | ||||||
| Male | Ref | Ref | Ref | |||
| Female | 24 (−79 to 128) | 0.6 | −153 (−204 to −103) | < 0.001 | 2.1 (1.2 to 3.0) | < 0.001 |
Definition of abbreviations: CI = confidence interval; FEF25–75 = forced expiratory flow between 25 and 75% of the FVC; Ref = reference.
Adjusted for height, weight, and age. Time-dependent covariates included in the model were height (cm), weight (kg), age (yr), and current wheeze. Preschool wheeze phenotypes and sex were included as fixed covariates. For the models, the number of observations was 955, the number of groups was 591, and the average number of observations per group was 1.6 (minimum, 1; maximum, 2).
Preschool wheeze phenotypes were defined as follows: no wheeze from birth to age 6 yr (never wheeze), wheezing lower respiratory illness (LRI) before age 3 yr only (transient early wheeze), wheeze at age 6 yr only (late-onset wheeze), and wheezing LRI before age 3 yr and wheeze at age 6 yr (persistent wheeze).
Infrequent wheeze was defined as one to three episodes of wheeze during the previous year and frequent wheeze was defined as four or more episodes of wheeze during the previous year.
Model-based coefficients represent deviations from the reference group; for example, persistent wheezers had a predicted FEF25–75 that was –259 ml/s lower than that of never wheezers and, if they were also frequent wheezers, these children had a predicted FEF25–75 that was –341 ml/s lower than that of children with no wheeze during the previous year, for an estimated total deficit of –600 ml/s.