Background: Lyme disease is the most common vector-borne disease in the United States, and the number of reported cases has more than doubled between 1992 and 2008. Few studies have explicitly examined sex-based differences in the clinical presentation of or serologic response to early Lyme disease. It is unknown whether the sex-based variability observed in other infectious diseases is relevant to this clinical setting.
Objective: This study retrospectively examined clinical and serologic differences by sex among a community case series of patients with a current or past episode of confirmed early Lyme disease.
Methods: This was a retrospective, consecutive case series of adult patients in Maryland enrolled from August 2002 to August 2007 meeting criteria for a current or past episode of confirmed early Lyme disease. Clinical variables and patients' self-report surrounding illness onset were abstracted through chart review. All serologic tests drawn within 3 months of illness onset were interpreted using Centers for Disease Control and Prevention criteria.
Results: In a total of 125 patients, there were no significant differences in clinical presentation by sex. The initial self-misdiagnosis rates for men and women were 10% and 18%, respectively (P = NS). Among the 62 patients with a serologic test as part of their clinical evaluation, 50% of men had a positive, 2-tier result compared with 32% of women (P = NS). Among the 41 patients with a positive ELISA, median ELISA values (3.4 vs 2.0; P = 0.03) and median number of immunoglobulin G (IgG) bands (4 vs 2; P = 0.03) were significantly higher among men.
Conclusions: In this small, retrospective sample, we found evidence for sex-based differences in the magnitude of ELISA and IgG serologic response to early Lyme disease. Such differences could have implications for appropriate diagnosis, treatment, and disease classification. Larger, prospective studies are needed to replicate the results found in this study and to examine their relationship to sex-based immunologic variability.
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