Validation of Claims-Based Algorithm for Lyme Disease, Massachusetts, USA

L yme disease is the most commonly reported vec- torborne disease in the United States (1) and is an economic burden for patients and society (2-4).As a notifiable disease, standard Lyme disease case definitions and reporting criteria have identified ≈30,000 cases annually via traditional surveillance (5).Several jurisdictions have used alternative methods to approximate Lyme disease incidence, including sampling (6), estimation techniques (7), and supplementing laboratory-based surveillance data with information from electronic health records (8).To complement traditional surveillance, the Centers for Disease Control and Prevention (CDC) used a commercial health care administrative claims database to estimate Lyme disease incidence in the United States.In 2015, claims-based algorithms were developed for inpatient and outpatient settings; the outpatient algorithm combined diagnosis codes from the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), for Lyme disease with dispensing of an antimicrobial drug within 30 days (9).That study estimated that ≈329,000 annual cases of Lyme disease occurred during 2005-2010 after applying several correction factors to account for database limitations.The analysis was repeated for cases during 2010-2018 after the addition of diagnosis codes from the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM), for Lyme disease, estimating that ≈476,000 Lyme disease cases occurred annually during this period (10).However, the accuracy of the algorithms is unknown (11).We validated this outpatient algorithm by assessing algorithm performance across age groups, healthcare facility type, and periods in a single Lyme disease-endemic state. Methods Study PopulationWe used Harvard Pilgrim Health Care (HPHC) administrative claims data to identify the initial Lyme disease cohort in Massachusetts, USA.HPHC is a notfor-profit health insurance company serving >3 million members primarily in the New England region of the United States.HPHC members are approximately Validation of Claims-Based Algorithm for Lyme Disease,Massachusetts, USA