HEALTHCARE COSTS ATTRIBUTABLE TO LYME DISEASE: A POPULATION-BASED MATCHED COHORT STUDY IN ONTARIO, CANADA

Purpose: To determine incidence-based healthcare costs attributable to Lyme disease from the healthcare payer perspective.

Method:

We conducted an incidence-based cost-of-illness study using individually linked laboratory, reportable disease and health administrative data from Ontario, Canada (population ~13 million). We established a cohort of incident confirmed Lyme disease cases (infected subjects) between 01/01/2006 and 31/12/2013. We matched infected subjects to uninfected subjects (1:3) using a combination of hard and propensity-score matching.

We used the phase-of-care approach to estimate attributable acute and long-term costs. We organized each subject’s observation time into 2 phases: acute infection and continuing care. Based on graphing costs, the literature and expert opinion we determined the length of acute illness to be 30 days; the remaining observation time was assigned to continuing care. We stratified costs by resource type (e.g., hospitalization, physician visits, ED visits), age and sex. Costs are reported in 2012 Canadian dollars, standardized to 10-days.

Result:

We identified 648 subjects with confirmed Lyme disease in the linked laboratory and reportable disease dataset, 641 were linked to health administrative data and 477 had follow-up data available. The mean age was 44.9 years (SD±20.1), 51.0% were female, 4.6% were hospitalized (any diagnosis, 2.0% with Lyme disease as most responsible diagnosis) and overall mortality was 1.7%. Mean follow-up time was 3 years. Mean 10-day phase 1 and 2 costs (95%CI) per infected subject were $291.53 ($209.57; $373.49) and $54.12 ($39.99; $68.24), respectively. Mean 10-day phase 1 and 2 costs (95%CI) per uninfected subject were $92.49 ($75.61; $109.37) and $51.94 ($43.85; $60.03), respectively. Mean 10-day phase 1, and 2 attributable costs were $199.10 ($115.70; $282.50) and $2.60 (-$13.30; $18.50), respectively. Attributable phase 1 costs were greater for males and those aged <20 years.

Expected mean attributable 1- and 3-year costs were $684.40 and $874.40, respectively.

Conclusion: Lyme disease is associated with increased acute but not long-term healthcare costs in confirmed cases compared with general population controls. However, further investigation of probable cases and those with possible Lyme disease-related sequelae such as Post-Treatment Lyme disease syndrome (PTLDS) is warranted to quantify implications of inappropriate antibiotic use and long-term impact in sub-populations. High-quality healthcare costs attributable to Lyme disease are important for healthcare planning and the evaluation of intervention strategies, including novel vaccines.