Nearly 500K Americans diagnosed with Lyme disease each year, analysis finds
An average of nearly half a million Americans are estimated to have received a diagnosis of Lyme disease each year from 2010 to 2018, according to a new analysis published in Emerging Infectious Diseases.
Lyme disease in commonly underreported in the United States. In 2017, for example, the U.S. reported a record number of tickborne diseases — nearly 60,000, most of them Lyme disease — but the CDC noted that the actual number of cases was much larger.
To get a better estimate, Kiersten J. Kugeler, PhD, MPH, an epidemiologist in the CDC’s Bacterial Diseases Branch, and colleagues used the IBM Watson Health MarketScan Commercial Claims and Encounters Databases to identify Lyme disease diagnoses by linking specific billing codes for patient encounters with antimicrobial prescriptions.
A similar analysis published in 2015 found that around 329,000 people in the U.S. were diagnosed with Lyme disease annually from 2005 to 2010.
In the new analysis, Kugeler and colleagues identified 118,780 individuals with a requisite code for Lyme disease from 2010 to 2018. Of these diagnoses, 81% occurred among residents of 14 high-incidence states in the Northeast, Mid-Atlantic and upper Midwest, and another 8% among residents of adjoining states.
The investigators reported that an average of 205,000 patients were coded and treated for Lyme disease each year. But upon further correction for omission of Lyme disease-specific codes in patient records, they estimated that an average of about 476,000 individuals received a Lyme disease diagnosis annually from 2010 to 2018 (95% CI, 405,000-547,000) — a significant increase over the 2005-2010 estimate.
“Although both estimates were calculated by using similar methods, we implemented a slightly more restrictive approach that prohibited any patient with a diagnosis of Lyme disease from being counted more than once during the 9-year study period,” Kugeler and colleagues wrote. “The observed increase in Lyme disease diagnoses between these two periods parallels increases in cases reported through surveillance.”
They said the estimates “underscore the large clinical burden associated with Lyme disease diagnoses in the United States.”
“Evolving electronic medical and laboratory systems should help fill demonstrable data gaps and enable more robust and reliable monitoring of changes in the magnitude and spread of the disease,” they wrote. “Effective interventions are needed, and improved awareness among clinicians and the public is paramount to foster early and accurate diagnosis and appropriate treatment.”
A second study by Amy M. Schwartz, MPH, also an epidemiologist in the CDC’s Bacterial Diseases Branch, and colleagues assessed MarketScan as a source of information on Lyme disease diagnosis in the U.S. and found that it “provide(s) a stable data source to monitor trends in Lyme disease diagnoses, but certain important characteristics”— such as which conditions, signs or symptoms are commonly mistaken for Lyme disease in some areas — “warrant further investigation.”
“As access to electronic data sources for health-related information increases, more diverse data can be queried to more comprehensively inform the epidemiology of Lyme disease,” the authors wrote. “However, when using novel data sources, the volume, stability, and representativeness must be considered before drawing inference.”
Clinical guidelines for Lyme disease were recently updated for the first time in 14 years.