BACKGROUND: Knowledge of co-occurring mental disorders (termed 'dual diagnosis') among patients receiving opioid agonist treatment (OAT) is scarce. This study aimed (1) to estimate the prevalence and structure of dual diagnoses in two national cohorts of OAT patients and (2) to compare mental disorders between OAT patients and the general populations stratified on sex and standardized by age. METHODS: A registry-linkage study of OAT patients from Czechia (N = 4,280) and Norway (N = 11,389) during 2010-2019 was conducted. Data on mental disorders (F00-F99; ICD-10) recorded in nationwide health registers were linked to the individuals registered in OAT. Dual diagnoses were defined as any mental disorder excluding substance use disorders (SUDs, F10-F19; ICD-10). Sex-specific age-standardized morbidity ratios (SMR) were calculated for 2019 to compare OAT patients and the general populations. RESULTS: The prevalence of dual diagnosis was 57.3% for Czechia and 78.3% for Norway. In Czechia, anxiety (31.1%) and personality disorders (25.7%) were the most prevalent, whereas anxiety (33.8%) and depression (20.8%) were the most prevalent in Norway. Large country-specific variations were observed, e.g., in ADHD (0.5% in Czechia, 15.8% in Norway), implying differences in screening and diagnostic practices. The SMR estimates for any mental disorders were 3.1 (females) and 5.1 (males) in Czechia and 5.6 (females) and 8.2 (males) in Norway. OAT females had a significantly higher prevalence of co-occurring mental disorders, whereas SMRs were higher in OAT males. In addition to opioid use disorder (OUD), other substance use disorders (SUDs) were frequently recorded in both countries. CONCLUSIONS: Results indicate an excess of mental health problems in OAT patients compared to the general population of the same sex and age in both countries, requiring appropriate clinical attention. Country-specific differences may stem from variations in diagnostics and care, reporting to registers, OAT provision, or substance use patterns.

• Keywords
• Dual diagnosis, Opioid agonist treatment, Opioid use disorder, Psychiatric comorbidity, Registry-based study,
• MeSH
• Diagnosis, Dual (Psychiatry) MeSH
• Adult MeSH
• Mental Disorders * epidemiology   drug therapy   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Opiate Substitution Treatment * statistics & numerical data   MeSH
• Analgesics, Opioid therapeutic use   MeSH
• Personality Disorders epidemiology   MeSH
• Opioid-Related Disorders * epidemiology   drug therapy   MeSH
• Prevalence MeSH
• Registries * MeSH
• Aged MeSH
• Sex Factors MeSH
• Anxiety Disorders epidemiology   drug therapy   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Norway epidemiology   MeSH
• Names of Substances
• Analgesics, Opioid MeSH

INTRODUCTION: During the COVID-19 pandemic, studies reported less number of hospitalizations for acute stroke and reduction in the use of recanalization treatments. This study analyzes nationwide data on stroke admissions and management in the Czech Republic during the first wave of the COVID-19 pandemic. METHODS: We compared the early COVID-19 pandemic (March-May 2020) with the pre-pandemic period (January-February 2020 and March-May 2019): (a) the National Register of Reimbursed Health Services provided volume of all admissions for subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), and ischemic stroke (IS), and volume of recanalization treatments (intravenous thrombolysis [IVT] and mechanical thrombectomy [MT]); (b) Registry of Stroke Care Quality provided door-to-needle time (DNT), onset-to-door time (ODT), and stroke severity at admission (National Institutes of Health Stroke Scale, NIHSS) for IS. RESULTS: During the pandemic (March-May 2020), the peak number of COVID-19 patients treated in Czech hospitals was 39 per million. In March-May 2020 versus March-May 2019, hospital admissions decreased as follows: stroke overall by 14% (p < 0.001), IS by 14% (p < 0.001), SAH by 15% (p = 0.07), and ICH by 7% (p = 0.17). The mean age was 74 years versus 74 years (p = 0.33), and 52% versus 51% were men (p = 0.34). The volumes of IVT and MT decreased by 14% (p = 0.001) and 19% (p = 0.01), respectively. The proportions of all IS patients receiving IVT or MT remained unchanged, with, respectively, 17% versus 17% receiving IVT (p = 0.86) and 5% versus 5% receiving MT (p = 0.48). DNT and ODT were 24 versus 25 min (p = 0.58) and 168 versus 156 min (p = 0.23), respectively. NIHSS at admission did not differ (6 vs. 6; p = 0.54). CONCLUSION: Even with a low burden of COVID-19 during the first wave and no change in organization and logistics of stroke services, stroke admissions and volume of recanalization treatments decreased. Public health communication campaigns should encourage people to seek emergency medical care for stroke symptoms during the COVID-19 pandemic.

• Keywords
• COVID-19, Czech Republic, Intravenous thrombolysis, Mechanical thrombectomy, Stroke,
• MeSH
• Stroke * therapy   MeSH
• COVID-19 * epidemiology   therapy   MeSH
• Humans MeSH
• Pandemics * MeSH
• Aged MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH