Lyme borreliosis in Finland: a register-based linkage study

Mikko Virtanen,Jukka Hytönen,Jussi Sane,Eeva Feuth,Otto Helve

doi:10.1186/s12879-020-05555-w

Abstract

BackgroundIn Finland, the routine surveillance of Lyme borreliosis (LB) is laboratory-based. In addition, we have well established national health care registers where countrywide data from patient visits in public health care units are collected. In our previous study based on these registers, we reported an increasing incidence of both microbiologically confirmed and clinically diagnosed LB cases in Finland during the past years. Here, we evaluated our register data, refined LB incidence estimates provided in our previous study, and evaluated treatment practices considering LB in the primary health care.MethodsThree national health care registers were used. The Register for Primary Health Care Visits (Avohilmo) and the National Hospital Discharge Register (Hilmo) collect physician-recorded data from the outpatient and inpatient health care visits, respectively, whereas the National Infectious Diseases Register (NIDR) represents positive findings in LB diagnostics notified electronically by microbiological laboratories. We used a personal identification number in register-linkage to identify LB cases on an individual level in the study year 2014. In addition, antibiotic purchase data was retrieved from the Finnish Social Insurance Institution in order to evaluate the LB treatment practices in the primary health care in Finland.ResultsAvohilmo was found to be useful in monitoring clinically diagnosed LB (i.e. erythema migrans (EM) infections), whereas Hilmo did not add much value next to existing laboratory-based surveillance of disseminated LB. However, Hilmo gave valuable information about uncertainties related to physician-based surveillance of disseminated LB and the total annual number of EM infections in our country. Antibiotic purchases associated with the LB-related outpatient visits in the primary health care indicated a good compliance with the recommended treatment guidelines.ConclusionsAvohilmo and laboratory-based NIDR together are useful in monitoring LB incidence in Finland. A good compliance was observed with the recommended treatment guidelines of clinically diagnosed LB in the primary health care. In 2018, Avohilmo was introduced in the routine surveillance of LB in Finland next to laboratory-based surveillance of disseminated LB.

Highlights

In Finland, the routine surveillance of Lyme borreliosis (LB) is laboratory-based
We investigated the epidemiology of LB in Finland for the period 1995–2014 by using the data of these health care registers [17]
We focused on two main hospital districts (HD) in Finland, Helsinki and Uusimaa HD and Varsinais-Suomi HD, which locate in the highly endemic LB area in south coast of Finland [17]

Summary

Introduction

In Finland, the routine surveillance of Lyme borreliosis (LB) is laboratory-based. In addition, we have well established national health care registers where countrywide data from patient visits in public health care units are collected. In our previous study based on these registers, we reported an increasing incidence of both microbiologically confirmed and clinically diagnosed LB cases in Finland during the past years. We evaluated our register data, refined LB incidence estimates provided in our previous study, and evaluated treatment practices considering LB in the primary health care. In Finland, EM is typically diagnosed and treated by general practitioners (GP) in the primary health care, whereas disseminated LB, such as Lyme neuroborreliosis (LNB), is treated in the hospitals or outpatient clinics of hospitals under the counselling of infectious diseases specialists. Some European countries have a mandatory notification system for LB [7, 8, 11,12,13] In those countries, LB surveillance is mostly based on laboratory surveillance resulting in that the clinically diagnosed EM is greatly neglected. In the countries without mandatory notification, LB incidence estimates are based on epidemiological studies conducted often in high-risk population or in high-endemic areas, not representing the burden of LB in general population nor in the whole country [14,15,16]

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Conclusion