Table 3.

Multinomial Logistic Regression Models for Airway Hyperresponsiveness as Measured from Age 11 to Age 26 Years^*

Airway Hyperresponsiveness	z-Score CC16	All Participants (n Subjects = 555; n Observations = 1,228)		No Asthma (n Subjects = 493; n Observations = 1,033)		Nonsmoker (n Subjects = 485; n Observations = 894)
		adjRRR (95% CI)	P Value	adjRRR (95% CI)	P Value	adjRRR (95% CI)	P Value
	Continuous CC16†
No drop		(Base outcome)
Mild		0.92 (0.77–1.10)	0.352	0.89 (0.73–1.09)	0.270	0.88 (0.70–1.09)	0.232
Moderate		0.75 (0.63–0.89)	0.001	0.76 (0.62–0.92)	0.006	0.63 (0.50–0.80)	<0.001
Severe		0.66 (0.55–0.81)	<0.001	0.63 (0.50–0.79)	<0.001	0.58 (0.45–0.73)	<0.001
	Category†
No drop		(Base outcome)
Mild	High CC16	(Reference group)
	Middle CC16	1.18 (0.80–1.73)	0.404	1.22 (0.81–1.82)	0.343	1.41 (0.91–2.18)	0.126
	Low CC16	1.19 (0.77–1.84)	0.426	1.21 (0.77–1.91)	0.405	1.38 (0.82–2.32)	0.221
Moderate	High CC16	(Reference group)
	Middle CC16	1.25 (0.84–1.86)	0.274	1.25 (0.81–1.94)	0.317	1.53 (0.94–2.48)	0.088
	Low CC16	1.86 (1.22–2.85)	0.004	1.88 (1.19–2.98)	0.007	2.62 (1.57–4.39)	<0.001
Severe	High CC16	(Reference group)
	Middle CC16	1.45 (0.96–2.18)	0.078	1.80 (1.12–2.89)	0.015	1.52 (0.97–2.39)	0.067
	Low CC16	2.30 (1.46–3.61)	<0.001	2.64 (1.54–4.51)	<0.001	3.05 (1.80–5.18)	<0.001

Definition of abbreviations: adjRRR = adjusted relative risk ratio; CC16 = club cell secretory protein 16; CI = confidence interval.

^*Subject-clustered sandwich estimators of SE were used in multinomial logistic regression models to adjust for within-subject correlation. All models were adjusted for sex, survey year, ethnicity, parental education, and maternal smoking at Year 6. Airway hyperresponsiveness severity (mild, moderate, severe) was defined at each survey based on tertiles of provocative concentration of methacholine causing a 20% fall in FEV₁ (see Methods section for more information).

^†Circulating CC16 levels were included as z-scores in the model.