Importance Lyme disease (LD) is the most common vector-borne illness in the US. Given the increasing prevalence and expanding geographic bounds of LD, in-depth, up-to-date understanding of costs associated with an LD diagnosis, including patient out-of-pocket (OOP) costs, is needed. Objective To assess health care costs in a broad US population diagnosed with LD, overall and stratified by localized disease vs disseminated disease. Design, Setting, and Participants This retrospective cohort study identified patients from Optum’s deidentified Market Clarity Data (Optum Market Clarity) between December 2, 2014, and January 30, 2023 (study period), with an LD diagnosis between January 1, 2016, and December 31, 2022 (identification period), having at least 14 months of continuous health plan enrollment. Optum Market Clarity is an integrated, multisource medical claims, pharmacy claims, and electronic health records data set. Outpatients had a claim with an LD diagnosis plus relevant antibiotics within 30 days, and inpatients had a claim with LD as the primary diagnosis or as a secondary diagnosis with an LD-associated condition as the primary diagnosis. Data were analyzed from February 27, 2023, to October 20, 2025. Exposure The main exposure was LD diagnosis. Case patients were classified as having disseminated, localized, or indeterminate LD based on diagnosis codes for LD and LD-associated conditions, inpatient vs outpatient services, or antibiotic treatment type. Main Outcomes and Measures Health care costs (reported in US dollars) for LD cases overall and stratified by localized disease vs disseminated disease were assessed 4 ways: (1) LD-specific costs per episode, (2) all-cause 6-month baseline vs follow-up costs for case patients with LD, (3) all-cause 6-month follow-up costs for case patients with LD compared with the control group, and (4) multivariable case-control analysis. Costs are reported as estimated direct (standardized) costs and patient OOP costs. Wald 95% CIs were used for means of cost measures. Results A total of 70 531 case patients with LD were included. Their mean (SD) age was 44. 8 (21. 3) years; 51. 3% were female. Estimated direct costs of LD were substantial across assessment methods, including episode cost (mean, 2227 95% CI, 2111-2342), case patients as self-controls analysis (difference, 3304 95% CI, 3117-3491 in mean 6-month costs between baseline and follow-up), case-control analysis (difference, 4098 95% CI, 3888-4307 in mean 6-month follow-up costs), and multivariable-adjusted analysis (case-control difference, 5571 in projected mean 6-month follow-up costs; cost ratio, 1. 96 95% CI, 1. 90-2. 02). OOP costs were available for 10 962 patients (15. 5%) with LD. Mean OOP costs attributed to LD ranged from 188 to 399. Extrapolating to the US population in high-incidence states, annual costs of LD could range between 591 million and 1. 05 billion (2022 dollars), with 411 to 771 million attributable to disseminated disease. Conclusions and Relevance In this retrospective cohort study, LD presented a large financial burden to the health care system and patients, especially for those with disseminated disease. These findings highlight the need for effective preventive measures to reduce costs for patients and the health care system.
Yu et al. (Wed,) studied this question.