METHODS: NH’s ED data system, which includes data from all 26 acute care hospitals in NH, was queried for tick bite and LD-related encounters. Chief complaint text was queried for words related to tick bites or erythema migrans. ICD-9 codes were queried for the LD diagnosis code (088.81). Probabilistic linkage (using date of birth, sex, resident town, and encounter date) was used to link ED patients to reportable disease data where possible to determine the proportion of ED patients reported to DHHS as a LD case. Data were analyzed to calculate frequencies for key demographic and reporting characteristics using Microsoft Excel.
RESULTS: A total of 13,125 tick bite or LD-related ED encounters were identified in NH from 2010 to 2014. The majority of ED visits were for tick bites alone (n = 10,122, 77%); 23% of visits had a corresponding LD ICD-9 diagnosis code (n = 3,003). During this same time period, 14,081 suspected LD cases were reported to DHHS. Among all 13,125 ED encounters, 837 (6%) of patients were reported to DHHS as having LD. Among ED patients with a LD ICD-9 diagnosis code, 723 (24%) were reported to DHHS as having LD. The sex and geographic distributions of ED patients were similar to reported LD cases with males in southeastern NH most affected. Seasonal distribution of ED encounters peaked earlier than reported LD cases. While age was similar among ED visits and reported LD cases, the proportion of young adults and adults >65 years was greater for ED encounters.
CONCLUSIONS: Patients frequently visit the ED to seek care for tick bites and illnesses suspected to be associated with LD. DHHS will use the results of these analyses to increase and target public and provider knowledge, in particular for ED providers, through promotion of evidence-based clinical guidelines and distribution of educational materials and training programs.