Lyme disease: Incidence of diagnosis in a Maryland Medicaid Population
Few studies have examined the epidemiology of Lyme disease through the use of health insurance claims, and all have utilized data from privately insured individuals.
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A new study by Johns Hopkins University School of Medicine researchers evaluate overall incidence rates and demographic, seasonal, and geographic trends of first Lyme disease diagnosis among 384,652 Maryland Medicaid members enrolled from July 2004-June 2011 and represents the first analysis of claims data from publicly insured individuals.
The goal of this study was to examine the epidemiology of Lyme disease diagnoses among publicly insured individuals. Specifically, calculations of overall incidence rates as well as age, gender, season, year, and county-level incidence rates of first Lyme disease diagnoses over a 7-year period in Maryland.
All residents enrolled in Priority Partners, a large Medicaid managed care organization in Maryland, at any point during a seven-year period (July 2004 to June 2011) were included in this study. The sample of 384,652 Maryland Medicaid members only included individuals under the age of 65 who had not transitioned to Medicare. Lyme disease diagnoses were identified through paid medical professional claims from office, urgent care, outpatient, inpatient, and emergency room visits.
This study finds that Lyme disease diagnoses do occur in a Medicaid population in the Lyme-endemic state of Maryland. After controlling for other factors, researchers found a 13% average annual increase in Lyme disease diagnoses, consistent with other reports of an increasing number of cases over time. This increase appeared to occur across all sub-groups (age, gender, season, and rurality). Consistent with the observed westward spread of Lyme disease in other reports, we found several counties west of the Chesapeake Bay to have rates comparable to those on the Eastern Shore.
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In adjusted analyses using mixed effects multiple logistic regression models with person as a random intercept, we did not find statistically significant differences by gender. However, urban counties were associated with 61% lower odds of Lyme disease diagnosis, and the odds of a Lyme disease diagnosis in fall/spring and summer months were 118% and 247% higher than those of the winter months. When interaction terms were introduced, we found gender and age differences in season of diagnosis, with increased risk among males compared to females in the summer when Lyme is traditionally diagnosed and increased risk among females compared to males in the winter low season. Similarly, adults had increased risk compared to children in the fall/spring and winter lower season months.
This study’s findings suggest that typical seasonal trends in Lyme disease, such as those found in traditional case reporting, may be more pronounced for certain demographic sub-groups than others, and further research is needed.
A higher percentage of Medicaid beneficiaries report barriers to care, delaying or foregoing care, and increased utilization of emergency departments than the privately insured. Notably, this may place them at increased risk of missed or delayed Lyme disease diagnosis and subsequent progression to more severe manifestations of the disease. Lyme disease education and prevention programs are needed and should be available to physicians who care for both publicly and privately insured individuals in a variety of clinical settings throughout geographically endemic regions.
