Addendum to "Migraine prevention with a supraorbital transcutaneous stimulator: a randomized controlled trial"
Jean ESchoenen, Co-Director Headache Research Unit
Published October 01, 2015
Additional statistical analyses were performed on the outcome measures presented in Schoenen et al. [1] to account for covariates. A rank analysis of covariance was performed, using the non-parametric Spearman's rank correlation coefficient. [2] The results showed that age and disease duration does not impact on study outcomes. However, the number of migraine days during the 1-month baseline period had an influence on the decrease in migraine days during the 3rd month of treatment. In the original publication, the difference between verum and sham groups in the reduction of migraine days (respectively -29.7% and -4.9%) just missed the significance threshold (p=0.054). [1] However, when baseline migraine days are considered as a covariate, this difference becomes significant (p=0.044). This analysis therefore suggests that the beneficial effect of Cefaly for migraine prevention might be greater in patients with more frequent migraines, which is of interest for clinical practice.
1. Schoenen J, Vandersmissen B, Jeangette S, et al. Migraine prevention with a supraorbital transcutaneous stimulator: a randomized controlled trial. Neurology 2013; 80:697-704.
2. Stokes ME, Davis CS, Koch GG. Categorical Data Using the SAS System, 2nd ed. Cary, NC: SAS Institute Inc.; 2000.
For disclosures, please contact the editorial office at journal@neurology.org.
Editor's Note: An update related to this letter will be published in an upcoming print issue.
Additional statistical analyses were performed on the outcome measures presented in Schoenen et al. [1] to account for covariates. A rank analysis of covariance was performed, using the non-parametric Spearman's rank correlation coefficient. [2] The results showed that age and disease duration does not impact on study outcomes. However, the number of migraine days during the 1-month baseline period had an influence on the decrease in migraine days during the 3rd month of treatment. In the original publication, the difference between verum and sham groups in the reduction of migraine days (respectively -29.7% and -4.9%) just missed the significance threshold (p=0.054). [1] However, when baseline migraine days are considered as a covariate, this difference becomes significant (p=0.044). This analysis therefore suggests that the beneficial effect of Cefaly for migraine prevention might be greater in patients with more frequent migraines, which is of interest for clinical practice.
1. Schoenen J, Vandersmissen B, Jeangette S, et al. Migraine prevention with a supraorbital transcutaneous stimulator: a randomized controlled trial. Neurology 2013; 80:697-704.
2. Stokes ME, Davis CS, Koch GG. Categorical Data Using the SAS System, 2nd ed. Cary, NC: SAS Institute Inc.; 2000.
For disclosures, please contact the editorial office at journal@neurology.org.
Editor's Note: An update related to this letter will be published in an upcoming print issue.