Use of Rescue Medication
The type of rescue medication (RM) varied across the eligible trials, including antihistamines, naphazoline nitrate, topical antihistamines, topical nasal corticosteroids, systemic corticosteroids, tramazoline hydrochloride and levocabastine hydrochloride. We assessed the use of RM in two different ways, depending on type of data that eligible studies provided. First, a daily mean score was calculated by adding the total number of different kinds of rescue medications used each day during the pollen season divided by the total number of days in the pollen season. Five studies with a total of 1,098 randomized patients provided enough data to allow for a quantitative evidence synthesis based on the RM as a daily mean score. In two studies10, 11, rescue medication score was defined as daily usage on a 4-point scale (0= no rhinitis medication; 1= topical nasal, ocular, or lung treatment apart from corticosteroids; 2= systemic antihistamines; 3= systemic or topical corticosteroids for nose or lung). When more than one rescue medication was used on the same day, only the maximal score medication was recorded. In the other three studies12-14, it was measured on a 4-point scale (0-3 points), but it was not described sufficiently how the score was generated. Overall, in the studies with appropriate data, omalizumab statistically significantly reduced the use of rescue medication mean score by a summary standardized mean difference of -0.11 points (95% CI: -0.16, -0.05; p<0.001; I2 = 62.9%) (Figure 4a).
Moreover, we assessed the use of rescue medication as daily mean consumption, i.e. the average daily rescue antihistamine tablets consumed by patients. Three studies with 797 randomized patients provided enough data to allow for a quantitative evidence synthesis based on the use of rescue medication assessed as mean daily consumption. Overall, omalizumab statistically significantly reduced the mean daily consumption of rescue medication with antihistamines by a summary standardized mean difference of -0.21 (95% CI, -0.41, -0.01; p=0.036; I2 = 85.7%) (Figure 4b).