Enhancing the accuracy of register‐based metrics: Comparing methods for handling overlapping psychiatric register entries in Finnish healthcare registers

Abstract Objectives Healthcare registers are invaluable resources for research. Partly overlapping register entries and preliminary diagnoses may introduce bias. We compare various methods to address this issue and provide fully reproducible open‐source R scripts. Methods We used all Finnish healthcare registers 1969–2020, including inpatient, outpatient and primary care. Four distinct models were formulated based on previous reports to identify actual admissions, discharges, and discharge diagnoses. We calculated the annual number of treatment events and patients, and the median length of hospital stay (LOS). We compared these metrics to non‐processed data. Additionally, we analyzed the lifetime number of individuals with registered mental disorders. Results Overall, 2,130,468 individuals had a registered medical contact related to mental disorders. After processing, the annual number of inpatient episodes decreased by 5.85%–10.87% and LOS increased by up to 3 days (27.27%) in years 2011–2020. The number of individuals with lifetime diagnoses reduced by more than 1 percent point (pp) in two categories: schizophrenia spectrum (3.69–3.81pp) and organic mental disorders (1.2–1.27pp). Conclusions The methods employed in pre‐processing register data significantly impact the number of inpatient episodes and LOS. Regarding lifetime incidence of mental disorders, schizophrenia spectrum disorders require a particular focus on data pre‐processing

Mental disorders and having a first child among young adults in Finland

Background: Fertility rates have declined during the 2010s in many high-income countries, with a strong decrease in Finland. Mental disorders might contribute to this decline, given that they became a major cause of work disability in Finland. We examined associations between broad and specific categories of mental disorders and the likelihood of having a first child among young people, and the role of partnership status in these associations. Methods: We conducted a nationwide register-based cohort study including all men and women born in 1980-1995 in Finland (n = 1,210,662). Exposures were mental disorders with ICD-10 subchapter F-diagnosis, and outcome was time to first childbirth. Results: The diagnosis of almost any mental disorder was associated with a lower likelihood of having a first child among men and women, with schizophrenia and intellectual disabilities having the strongest associations. People with substance use, childhood onset, anxiety, or any mental disorders had a higher rate of having a first child by age 25 than people without these diagnoses; by age 30-35 these associations became negative. People with mental disorders were also less likely to cohabit. Among those who never cohabited, women with substance use disorders or childhood onset disorders were more likely to have a first child compared to women without these disorders. Conclusions: Almost all mental disorders were associated with a lower rate of having a first child, especially among men. These findings imply that well-functioning mental health services are important also from a fertility perspective, which should be considered by policy makers

Transmission of mental disorders in adolescent peer networks: a Finnish nationwide registry study

ImportancePrevious research indicates that mental disorders may be transmitted from one individual to another within social networks. However, there is a lack of population-based epidemiological evidence that pertains to the full range of mental disorders.ObjectiveTo examine whether having classmates with a mental disorder diagnosis in the ninth grade of comprehensive school is associated with later risk of being diagnosed with a mental disorder.DesignCohort members were followed from August 1 in the year they completed ninth grade (around age 16) until a diagnosis of mental disorder, emigration, death, or December 31, 2019, whichever occurred first.SettingPopulation-based registry study.ParticipantsData of all Finnish citizens born between January 1, 1985 and December 31, 1997 whose demographic, health, and school information were linked from nationwide registers.ExposureThe exposure was one or more individuals diagnosed with a mental disorder in the same school class in the ninth grade. Main Outcomes and MeasuresBeing diagnosed with a mental disorder during follow-up.ResultsAmong the 713 809 cohort members (50.4% of whom were males), 47 433 had a mental disorder diagnosis by the ninth grade. Of the remaining 666 376 cohort members, 167 227 persons (25.1%) received a mental disorder diagnosis during follow-up (7 324 958 person-years). A weak dose-response association was found, with no significant increase in later risk of being diagnosed with one diagnosed classmate (HR=1.01, 95% CI 1.00–1.02), but a 5% increase with more than one diagnosed classmate (HR=1.05, 95% CI 1.04–1.06). The risk was not proportional over time but was highest during the first year of follow-up, showing a 9% increase for one diagnosed classmate (HR=1.09, 95% CI 1.04–1.14), and an 18% increase for more than one diagnosed classmate (HR=1.18, 95% CI 1.13–1.24). Of the examined mental disorders, the association was strongest for mood, anxiety, and eating disorders. These associations persisted after adjusting for an array of parental, school-level, and area-level confounders.Conclusions and RelevanceMental disorders might be transmitted within adolescent peer networks. More research is required to elucidate the mechanisms underlying the possible transmission of mental disorders. <br/