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November 2007

Optic Neuritis and Vaccination Investigation: Failure to Consider Significant Sex Differences and Multiple Vaccine Combinations

Arch Neurol. 2007;64(11):1673-1674. doi:10.1001/archneur.64.11.1673

In follow-up to recent correspondence related to the study of vaccinations and subsequent optic neuritis by the Centers for Disease Control and Prevention (CDC),1,2 we are deeply concerned regarding the lack of consideration of sex differences in incidence of disease for the ICD-9 code 377.3, a common finding for autoimmune disorders, particularly in young adults aged 18 to 39 years. The Defense Medical Surveillance System (DMSS) demonstrates that in the population of service members of greatest concern, there is a consistent pattern, regardless of year for review, of increased disease incidence by first visit in women compared with men. This sex difference is also independent of race. The Figure was extracted from the remote access program to data contained within the DMSS offered by the Army Medical Surveillance Activity.3 Similar sex differences were identified for ICD-9 codes for optic neuritis, unspecified (377.30); optic papillitis (377.31); retrobulbar neuritis, acute (377.32); and optic neuritis, other (377.39) during the period between January 1, 1998, and December 31, 2003. It is of increasing concern in the context of medical evidence and research that sex differences are not adequately considered in both research design and data analysis. Given the mandatory nature of immunizations in the military health system and the fact that most visits involve complex and sometimes new mixtures, concern for sex-based risk differences is not a minor question and merits far more attention on the agenda of vaccine safety surveillance.

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