Abstract
OBJECTIVES: Serologic testing is a useful adjunct for the diagnosis of Lyme disease, a major public health problem in certain US regions. We aimed to determine whether Lyme disease serologic testing and results differed by sex and age group. METHODS: We identified 2 cohorts of individuals across all ages who underwent serologic testing for Lyme disease at a national reference laboratory in 2019 (cohort 1) and 2022 (cohort 2). If an individual had multiple tests in the same year, we included only the first test. We excluded individuals who had been tested in the previous 5 years. RESULTS: Cohorts 1 and 2 consisted of 578 052 and 550 674 people, respectively. Fewer males than females were tested in cohort 1 (42.7% vs 57.3%) and cohort 2 (42.3% vs 57.7%), although similar numbers were tested for both sexes among nonadults. More males than females had a positive test result in cohort 1 (53.9% more males) and cohort 2 (52.9% more males). The odds ratio of receiving a positive test result among males versus females was 2.09 (95% CI, 2.01-2.17) in cohort 1 and 2.12 (95% CI, 2.05-2.19) in cohort 2. Among people with positive test results, females (except children) were more likely than males to have positive immunoglobulin M and negative immunoglobulin G results, which can serve as a marker of early infection (odds ratio = 1.43 [95% CI, 1.31-1.55] in cohort 1 and 1.38 [95% CI, 1.29-1.47] in cohort 2). CONCLUSIONS: Further studies are needed to understand whether the observed differences in Lyme disease testing and positivity result from sex- and age-associated disparities in social behavior, health care seeking, clinical practice, or other factors.