We thank the authors for their letter and appreciate the opportunity to respond to their concerns on our published study evaluating anthrax vaccination and risk of optic neuritis in the US military.1 As the authors point out, there is a consistent pattern of an increased incidence of optic neuritis for women vs men in the military. Approximately 15% of the active duty military population is female; however, in our study population, women constituted 30.7% of the analyzed optic neuritis cases. We estimate that women are about 2.5 times more likely than men to be diagnosed with optic neuritis in the military, consistent with the authors' figure. Because sex is likely a confounder, we controlled for it by including sex as a matched factor in our matched case-control analysis.
Payne DC, Rose CE, Kerrison J, Aranas A, Duderstadt S, McNeil MM. Optic Neuritis and Vaccination Investigation: Failure to Consider Significant Sex Differences and Multiple Vaccine Combinations—Reply. Arch Neurol. 2007;64(11):1674-1675. doi:10.1001/archneur.64.11.1674