Data Analysis

We used IBM SPSS Statistics 20.0 to conduct data analysis. Data entries were double-checked, with inconsistencies reconciled by reference to the original documents. An error rate of 1.9% was identified. The 1-year prevalence of primary headache disorders was reported as a percentage with 95% CIs. An adjusted prevalence for gender and school grade according to the participation of Kuwaiti students was also reported. Duration of headache was recorded as continuous data in hours. Headache frequency was recorded in days over the preceding 3 months, and typical headache intensity was reported on a verbal rating scale (“not bad,” “quite bad,” and “very bad”). We used proportions, 95% CIs, means, and SDs to summarize the distributions of variables and chi-square for significance of differences. P < 0.05 was considered as statistically significant.