# Prevalence of Adolescents’ Persistent High Utilization of Outpatient Healthcare Services and ICD-10 Diagnoses: A Retrospective 4-Year Population-Based Register Study

## TL;DR

This study finds that a significant portion of adolescents have persistent high healthcare use, especially for mental and musculoskeletal issues.

## Contribution

The study introduces a new definition and analysis of persistent high healthcare utilization in adolescents.

## Key findings

- 18.5% of adolescents were persistent high healthcare utilizers over four years.
- Mental and behavioral disorders were most prevalent among persistent high utilizers.
- Single-year high utilization strongly predicts future persistent use.

## Abstract

Persistent high healthcare utilization has rarely been analyzed in adolescent populations although there are specific chronic health issues also among adolescents, like mental health challenges and some somatic illnesses, which need long-term treatments. Therefore, it remains unclear whether such high utilization is persistent among adolescents. Recognizing patterns of high service utilization and its’ persistence are essential for preventing avoidable healthcare use.

This population-based study focused on all adolescents born in 2004 (n = 1483) from North Karelia, Finland. Healthcare service use data (2018-2021) was extracted from the electronic patient register. A high utilizer of healthcare (HU: the abbreviation also refers to high utilization) was defined as a person having been in contact with healthcare services during at least 12 days a year (attendance days). A persistent HU (pHU) was a person identified as being HU during 3 or 4 of all 4 follow-up years. The prevalence of diagnoses set to young people was compared in accordance with ICD-10 diagnostic categories between pHU and non-pHU groups.

pHUs accounted for 18.5% (n = 275) of all adolescents born in 2004. A total of 53.5% (n = 793) of adolescents met the criteria of single-year HU during the follow-up period, and of these, 34.7% were also identified as pHU. The pHU group was particularly emphasized in mental and behavioral disorders (RR = 4.5, CI: 3.6-5.5, P < .001), as well as the diseases of the nervous system (RR = 3.4, CI: 2.2-5.1, P < .001) and musculoskeletal system/connective tissue (RR = 3.2, CI: 2.4-4.3, P < .001).

The continuation from single-year to multi-year HU was relatively high. Thus, single-year high utilization is a strong indicator of future persistence in healthcare service utilization. Further research is needed to identify differences in clinical and psychosocial characteristics between single-year high utilizers and those whose high-utilization continues for years.