Multiple statistical comparisons increase the chance that significant findings are due to

chance. Readers should be aware of this limitation when interpreting the clinical significance of the findings. Although our findings are generally consistent with those of other studies, no adjustment was made to the nominal alpha level. Thus, these results are best viewed as descriptive and hypothesis-generating rather than conclusive. Interpretation of the results should emphasize the width of the CIs rather than their corresponding P values. Third, we did not correct for potential correlations stemming from the possibility that multiple members of a single household contributed data to our analyses. However, this is unlikely

to have an effect on prevalence statistics or other main findings. Fourth, although some VX-809 cell line of the results are presented as both unadjusted and adjusted for sociodemographic variables, for the sake of parsimony, ABT-888 cost only unadjusted results are presented in Tables 5-7. It is possible that some of the outcomes such as healthcare resource utilization are affected by socioeconomic variables in addition to sex. These relationships have been explored in other AMPP Study based manuscripts and are also targets for future analyses. Finally, the analysis was cross-sectional in design, which limits our ability to examine causal relationships or longitudinal trajectories. Strengths of this study include its large sample size, population-based format, and symptom items that allow for assignment of ICHD-2 headache diagnoses. In addition, several validated instruments were used including the MIDAS questionnaire. These findings extend previous research showing that migraine and PM are not only more prevalent in females, the but also more disabling and associated with more

symptoms and greater healthcare resource utilization. For the most part, we did not find corresponding sex differences in other (nonmigraine spectrum) severe headache. Future research into sex differences in migraine and other severe headache types should continue to explore both biologic and psychosocial hypotheses. It is imperative that females are included in both basic science and clinical studies of sex differences in headache biology and expression. Greater understanding of biologic and psychosocial factors will shed light on observed sex differences in prevalence, treatment seeking, diagnosis and treatment of migraine and nonmigraine spectrum headache and will create opportunities to improve care and outcomes for both sexes. The authors would like to thank C. Mark Sollars, MS, and Jelena M. Pavlovic, MD, PhD, for editorial support, Christa A. Bruce, MS, for editorial support and project management and Michael T. Lynch for assistance with graphics. (a)  Conception and Design (a)  Drafting the Manuscript (a)  Final Approval of the Completed Manuscript “
“Objective.