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Table 4 Adjusted change in annual ICS days-of-supply for lower and higher-cost ICS users in 2003: restricted vs. unrestricted coverage

From: The impact of generic-only drug benefits on patients' use of inhaled corticosteroids in a Medicare population with asthma

  Change in ICS Days-of-Supply from 2003 to 2004 Change in ICS Days-of-Supply from 2003 to 2004: Restricted vs. Unrestricted Coverage (Difference-in-difference)
  Restricted Coverage Unrestricted Coverage Restricted vs. Unrestricted (95% CI) p-value
All Subjects (n = 1,802) -30.27 -14.81 -15.47 (-24.98, -5.95) 0.001
Lower-cost ICS Users in 2003 (n = 1,140) -26.38 -13.55 -12.84 (-24.34, -1.33) 0.029
   Continued using lower-cost ICS in 2004 (n = 960) -13.08 0.63 -13.71 (-25.52, -1.90) 0.023
   Switched to higher-cost ICS in 2004 (n = 25) -54.24 29.51 -83.75 (-171.58, 4.07) 0.060
Higher-cost ICS Users in 2003 (n = 662) -37.40 -15.60 -21.80 (-38.46, -5.13) 0.010
   Continued using higher-cost ICS in 2004 (n = 354) -39.81 -1.19 -38.62 (-56.96, -20.28) < .001
   Switched to lower-cost ICS in 2004 (n = 212) 0.71 -18.04 18.75 (-27.46, 64.96) 0.425
  1. Notes: Each row represents a separate OLS regression model. Among lower-cost ICS users in 2003, 155 subjects had no ICS drug use in 2004, among higher-cost ICS users in 2003, 96 subjects had no ICS drug use in 2004. We calculated mean changes in ICS days-of-supply for each coverage group by using the lincom command in Stata 8.2 and the mean levels of the covariables.