(229) Characterizing incident antidepressant use in young people in Norway: pathways to treatment and follow-up in specialist healthcare

Background: Antidepressant use has increased in young people. Little is known about the diagnostic practice driving this pattern or whether recommendations for close follow up are followed in practice.

Objectives: To describe recent incident antidepressant users ages 12-24 in Norway according to sex differences, diagnoses received prior to treatment and contact with specialist health care before and after treatment initiation.

Methods: Population-based study using linked data from health- and population registers. All persons aged 12-24 who filled a first prescription of an antidepressant (ATC N06A) during 2015-2019 (5-year wash-out) were included. We calculated the average incidence for 2015-2019 using population denominators. We identified potential indications for antidepressants from diagnosis codes from specialist care (ICD-10), and diagnosis and symptom codes from primary care (ICPC-2) from 365 days before to the day of the index prescription, and drug reimbursement codes. We assessed contact with specialists (child and adolescent or adult mental health services) up to 30 days before the index prescription, and follow-up with specialists in the 30 days following initiation.

Results: From 2015 to 2019, we identified 42,344 individuals who initiated antidepressants at ages 12-24 (overall incidence 10 per 1000). Incidence was higher in females than males and peaked at age 19 in females (20 per 1000) and 23 in males (12 per 1000). The largest difference was at age 16 when the incidence was 3.2-times higher in females, but the difference became less pronounced at older ages (1.5-times at age 24). The prevalences of potential indications prior to initiation were similar in males and females, except for a higher prevalence of migraine/headaches in females. Anxiety or depression was present in over 80% across all ages, however, 29% of those had only symptoms recorded. The proportion seeing a specialist in the month before initiation decreased with age, ranging from over 65% to 23% (54% 12-18 years; 28% 19-24 years). Among those seen in child and adolescent mental health services before the first antidepressant prescription, 11% were not seen in the month after, whereas 76% were seen two or more times. For adult mental health services, the corresponding numbers were 18% not seen in the month after initiation and 60% seen two or more times.

Conclusions: Approximately 1% of young people aged 12-24 initiated antidepressants from 2015-2019 in Norway. Around half of children aged 12-18 did not see a specialist in the month before starting antidepressant treatment. However, those seeing specialists seem to be followed closely in the month after initiation. For young people aged 19-24, it was uncommon to see a specialist before initiating antidepressants.