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. Author manuscript; available in PMC: 2014 Jun 1.
Published in final edited form as: J Allergy Clin Immunol. 2013 Mar 14;131(6):10.1016/j.jaci.2013.01.034. doi: 10.1016/j.jaci.2013.01.034

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.