Table 3.

Multivariate model of predictors of longitudinal post-bronchodilator FEV1 (mL)

	Main effect	Age Interaction effect
Baseline Predictors
Post-BD tdFEVl Max BD	−7.8 [−10.8,−4.7]‡	-
reversibility FEV1 (Max Post% - Pre%)	3.5 [−3.1,10.1]	0.3 [−0.8,1.4]
Female	−34 [−211,143]	-
Race/ethnicity (Black=reference)		-
White	14 [−81,109]	-
Hispanic	−26 [−160,108]	-
Other	68 [−119,256]	-
Time-varying Predictors
Age	−33 [−64,−2]*	NA
Severe asthma	51 [−34,135]	−9 [−20,1]
Exacerbations	Main effect Boys	Age interaction Boys	Main effect Girls	Age interaction Girls
1–2	61 [−53,175]	−11 [−25,4]	72 [−60,205]	−9 [−25,7]
3+	100 [−56,255]	−22 [−44,−0.2]*	38 [−169,245]	6 [−21,34]
Exacerbations 1- year lag	Main effect Boys	Age interaction Boys	Main effect Girls	Age interaction Girls
1–2	28 [−78,135]	−6 [−19,7]	33 [−95,162]	−7 [−22,9]
3+	121 [−24,265]	−30 [−51,−10]†	−16 [−187,154]	6 [−15,27]
BMI percentile
Overweight	71 [−43,185]	−7 [−21,7]
Obese	140 [25,255]*	−19 [−35,−4]*
Height Predicted FEV1	5.2 [−0.2,10.6] 1.01 [0.87,1.15]†	-

^*P<0.05

^†P<0.01

^‡P<0.001

Multivariate linear mixed model clustered at the participant level. A random intercept and random slope for age were allowed to correlate. Unit of change for continuous predictors: Post-BD tdFEV1, one percent absolute change in percent predicted; Max BD reversibility FEV1, one percent absolute change in percent predicted; age, 1 year. Age in years was recoded to be age minus six so that coefficients for age and age interactions could be interpreted in terms of years since age six years (the youngest age at baseline). The interpretation of the main effect can be 1) the effect of the variable at age 6 years if an age interaction term is present, or 2) the effect of the variable at every age if an interaction term is not present.