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Table 3 Number of dropouts and days with headache and migraine per 4 weeks related to treatment sequence and use of placebo in baseline period (N = 264)

From: The crossover design for migraine preventives: an analyses of four randomized placebo-controlled trials

 Placebo given in baseline periodPlacebo not given in baseline periodAll
Treatment sequencePlacebo in first periodActive treatment in first periodPlacebo in first periodActive treatment in first periodPlacebo in first periodActive treatment in first period
Number included60606084120144
Dropouts during first period25111316
Migraine days/month, mean (SD)
 Baseline period6.0 (2.9)6.2 (3.4)5.5 (2.4)5.2 (2.9)5.8 (2.7)5.6 (3.1)
 Placebo treatment period5.0 (3.0)5.5 (3.2)3.9 (2.2)3.9 (2.7)4.4 (2.6)4.6 (3.0)
 Washout period4.6 (3.9)15.9 (4.3)13.8 (3.1)24.0 (2.7)24.2 (3.5)24.8 (3.6)2
 Number of responders (% of eligible)416 (27.6)515 (27.3)516 (27.1)524 (32.9)532 (27.4)539 (30.5)5
Headache days/month, mean (SD)
 Baseline period8.4 (3.7)9.8 (5.3)6.8 (3.0)7.7 (4.1)7.6 (3.5)8.5 (4.8)
 Placebo treatment period7.0 (4.1)7.4 (4.1)4.9 (2.8)5.7 (3.9)5.9 (3.6)6.4 (4.1)
 Washout period6.1 (4.3)39.1 (6.5)34.5 (3.5)15.6 (4.2)15.3 (4.0)37.1 (5.6)3
 Number of responders (% of eligible)413 (22.4)513 (23.6)516 (27.1)519 (26.0)529 (24.8)532 (25.0)5
  1. Washout headache/migraine according to treatment sequence compared by Students t-test: 1P ≥ 0.08 2P ≥ 0.16 3P ≤ .005
  2. 4 Responders are defined as having at least 50% reduction in number of days/month. Eligible is defined as number included minus dropouts
  3. Number of responders related to treatment sequence compared by Chi-square test: 5P ≥ 0.47
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