Incidence of Lyme Disease Diagnosis in a Maryland Medicaid Population, 2004-2011

Abstract

The epidemiology of Lyme disease has been examined utilizing insurance claims from privately insured individuals; however, it is unknown whether reported patterns vary among the publically insured. We examined incidence rate trends of first Lyme disease diagnosis among 384,652 Maryland Medicaid members enrolled from July 2004-June 2011. Age, gender, county, season, and year-specific incidence rates were calculated, and mixed effects multiple logistic regression models were used to study the relationship between diagnosis and these variables. The incidence rate in our sample was 97.65 per 100,000 person-years (95% confidence interval (CI): 91.53, 104.06), and there was a 13% average annual increase in odds of diagnosis (odds ratio: 1.13, 95% CI: 1.09, 1.17, P < 0.001). Incidence rates for males and females were not significantly different, though males were significantly more likely to be diagnosed during high season months (relative risk [RR]: 1.24, 95% CI: 1.06, 1.44) and less likely to be diagnosed during low season months (RR: 0.63, 95% CI: 0.46, 0.87) than females. Additionally, adults were significantly more likely to be diagnosed during low season months (RR: 1.59, 95% CI: 1.19, 2.12) than children. While relatively rare, Lyme disease diagnoses do occur in a Medicaid population in a Lyme-endemic state.