Hospital Contacts for Infectious Diseases Among Children in Denmark, Finland, Norway, and Sweden, 2008-2017

Abstract

Purpose: Comparing rates of childhood infectious disease hospitalisations across countries may uncover areas for improvement in the prevention of severe childhood infections. We compared rates of childhood infectious disease hospital contacts across Denmark, Finland, Norway, and Sweden with the overall objective to elucidate potential differences in burden of disease and in organisational and registration practices.

Methods: Using national registries, we estimated incidence rates for infectious disease hospital contacts between 2008 and 2017 among children aged 0-14 years. We investigated the rates for different types of contacts (inpatient or outpatient including emergency room), duration of admission, and by sex.

Results: During the study period, the rate of all hospital contacts per 1000 person-years was highest in Sweden (125.2) followed by Finland (87.1), Denmark (79.0), and Norway (62.1). The rates aligned for inpatient contacts with overnight stays; 19.3 (Denmark), 16.6 (Finland), 16.3 (Norway), and 13.0 (Sweden); these were highest in early infancy in all countries. A peak around 1 year of age was seen in all countries except in Sweden. The rates were higher among boys compared with girls in early childhood, after 13 years of age the rates among girls surpassed the boys.

Conclusion: Large cross-country differences were observed for outpatient and short-term hospital contacts for infectious diseases, affected by differences in organisational structures and coding practices across and within countries over time. Inpatient contacts requiring overnight stays reflected more comparable levels of severe infections across countries. Childhood infectious disease morbidity was greatest among boys and before 2 years of age.

Keywords: Nordic countries; infectious disease hospitalisations; multinational study; paediatric; patient registry.

Figure 1

Age-standardized incidence rate (per 1000 person-years) of infectious disease episodes^a with hospital contacts among children aged 0–14 years by epidemiological year (2008/2009‒2016/2017), country and type of hospital contact. ^aHospital contacts with infections, which occur less than 14 days after discharge/visit date of a previous contact with infection are defined as the same infectious disease episode.

Figure 2

Incidence rate (per 1000 person-years) of infectious disease hospital episodes^a for epidemiological years 2008/2009‒2016/2017, by age, country, and type of hospital contact. ^aHospital contacts with infections, which occur less than 14 days after discharge/visit date of a previous contact with infection are defined as the same infectious disease episode.

Figure 3

Age-standardized incidence rate (per 1000 person-years) of infectious disease hospital contacts^a among children aged 0–14 years by group of infection^b, epidemiological year (2008/2009‒2016/2017), country and type of hospital contact. ^aHospital contacts with infections, which occur less than 14 days after discharge/visit date of a previous contact with infection are defined as the same infectious disease episode. ^bDifferent types of infections within an infectious disease hospital episode are counted, thus summing the rates over types of infections will give greater rate, than the rates presented in Figure 1.

Figure 4

Incidence rate (per 1000 person-years) of inpatient contacts with minimum 1 overnight stay for epidemiological years 2008/2009‒2016/2017 by group of infection^a, age, and country. ^aDifferent types of infections within an infectious disease hospital episode are all counted toward that type of infections (eg if both ICD-10 codes for GI and LRTI is registered during an infectious disease hospital episode the contact is counted both as GI and LRTI), thus summing the rates over types of infections will give greater rates, than the rates presented in Figure 1.

Figure 5

Incidence rate (per 1000 person-years) of infectious disease inpatient hospital episodes^a with minimum 1 overnight stay for epidemiological years 2008/2009‒2016/2017 by age, sex, and country. ^aHospital contacts with infections, which occur less than 14 days after discharge/visit date of a previous contact with infection are defined as the same infectious disease episode.