TABLE II.

Pre-enrollment disease activity (AIMS cohort) among episodes that were or were not treated with OCSs

Covariate	Episodes that were not treated with OCSs (n = 646)	Episodes that were treated with OCSs (n = 152)	Wald statistic before propensity adjustment (Pvalue)*	Wald statistic after propensity adjustmenty† (Pvalue)*
Demographics and AIMS study covariates
Age (mo)	30 (0.84)	29 (0.84)	4.3 (.04)*	0.2 (.65)
Male sex (%)	63	57	0.4 (.55)	0.7 (.40)
Race (O/AA/W [%])	10/7/83	3/16/81	18.8 (<.001)*	0.5 (.79)
Ethnicity (Hispanic [%])	17	16	4.4 (.04)*	0.8 (.37)
Drug arm (LTRA, ICS, albuterol [%])	36/44/19	45/35/20	3.3 (.19)	0.5 (.79)
Asthma history (past 12 mo before randomization)
No. of physician’s office visits for wheezing	4.04 (0.23)	4.68 (0.57)	0.9 (.34)	0.01 (.92)
No. of ED visits for wheezing	1.01 (0.16)	0.96 (0.34)	0.01 (.91)	0.2 (.63)
≥4 Wheezing exacerbations (%)	70	77	7.2 (.01)*	0.1 (.76)
Receive ≥1 course of OCS (%)	60	74	7.6 (.01)*	0.3 (.61)
Atopic characteristics (on randomization)
Positive skin test response to aeroallergen (%)	46	57	3.8 (.05)	1.9 (.17)
Positive API response (%)	61	72	8.5 (.01)*	0.2 (.70)

Data are presented before and after adjustment by the propensity model and expressed as means (SEs), except as noted. Repeated-measures models were used to adjust for multiple events within subjects. Propensity score adjustment was performed based on the natural log transformation (to improve normality) of the maximal score in each episode.

AA, African American; API, Asthma Predictive Index; ED, emergency department; LTRA, leukotriene receptor antagonist; O, other; W, white.

^*P < .05.

^†Statistics after propensity model adjustment were included to demonstrate effective adjustment of baseline covariate differences between the groups by using the propensity score.