Children/adolescents with a history of pTBI had lower educational attainment than our reference population with orthopedic injuries. People in the pTBI group did not move from upper secondary education to tertiary education as often as the reference group. People in the pTBI group also did not move from lower tertiary education to higher tertiary education as often as the reference group. When evaluating people within the pTBI group, specific intracranial injuries were associated with a lower educational attainment than concussions. In contrast, concussion patients had lower educational attainment than reference group.

Our comparisons were done using a unique reference group with injury background. Our hypothesis was that mimicking risk taking behavior we could see more reliable results for the impact of TBI to educational attainment. According to Statistics Finland, 50.1% of 26-year-old general population had a degree in upper secondary education in 2018 [30]. Total of 32.1% have a degree in lower tertiary education and 17.8% has degree in higher tertiary education [30]. As we can see in these statistics, the general population has notably higher proportion of tertiary education degrees compared to pTBI and reference group that supports our hypothesis.

Previous literature on this topic is scarce, but our results regarding the association of pTBI with lower educational attainment are consistent with earlier reports. A previous nationwide Swedish cohort study reported that adolescents with a history of pTBI did not attain secondary education to the level of the general population [19]. Swedish and Finnish education systems are similarly constructed and both are free of charge, making the data comparable [31]. Our study had more educational levels to compare as well as a more comparable reference population comprising people with an injury background.

An extensive Scottish cohort study showed a large scale of adverse educational outcomes that were more common in those with a TBI background [17]. Children/adolescents with a history of TBI needed more special education, were absent more often, had lower education attainment, and were excluded from school more than the general population [17]. Several studies implicated a negative longer-term impact on memory function, cognitive flexibility, and mental health problems, with the impact increasing as the severity of the TBI increases [15, 16, 18, 32]. Our study findings enhance these findings showing that the possible far-reaching impact on educational attainment could extend from the upper secondary level of education to the tertiary level.

Especially the incidence of mild pTBI has been on the rise in Finland during the study period [5]. In our data, pediatric patients with concussions had considerably lower educational attainment at all higher levels than reference population. Concussions are the mildest diagnose code in this injury category and implicate a mild TBI with no severe symptoms/imagining findings. Dipnall et all also found that minor TBI had negative impact on educational attainment which was not found on wrist/ankle injury patients [21] The difference was considerable more clearer in our data. Notably, a negative impact on educational attainment was also seen in pTBI patients with specific intracranial injuries compared to those with concussion. This could implicate a dose–response relationship, i.e., the impact is greater with more serious injuries.

Upper secondary education starts around 16 years of age in Finland. At this age, Finnish students make a big decision in their lives to go either on a more academic route of general upper secondary school or vocational education and training. In our study, the pTBI group considerably more often chose vocational training compared with the reference population. This difference was also seen with possibly more serious, specific, intracranial injuries compared with concussions. Our study groups’ mean ages were well under 16, suggesting that most these injuries occurred under the age of 16 and possibly affected the decision regarding these further educational routes.

This study has multiple strengths. The Finnish Care Register for Health Care has excellent coverage and quality [33]. The ICD-10 classification remained the same throughout the study period and the consistency of marking these codes to registers is excellent. The Finnish educational system is well constructed, free of charge, and underwent no major alterations during our study period. We had extensive and broad data that comprised all higher educational levels in Finland and allowed reliable comparisons. Even though socioeconomic status influences access to education, free education that is financially available to everyone makes it more equally achievable. A weakness of our study is the lack of specific information on pTBI severity as well as reliable information on people who missed upper secondary education. Our analyses were only adjusted for age, sex and year of the injury, lacking information on other potential confounders such as parental education, neighborhood/urban or other prior/childhood mental or physical morbidity (Fig. 3). In sensitivity analyses, we studied the impact of potential unmeasured confounders in form of the E-values (Appendix 1). The calculated E-values indicate that the impact of unmeasured confounders would have to be highly notable in order to explain away our effect estimate.