Incidence and Determinants of COVID-19 in Patients Seeking Treatment for Substance Use Disorder: A Patient-Based Linkage Study.

INTRODUCTION: People with substance use disorder (SUD) may be at increased risk of COVID-19 infection. However, there is little evidence regarding the incidence of and determinants associated with infection in this group. The aims of the study were to determine the cumulative incidence of COVID-19 among people who sought treatment for heroin, cocaine, cannabis, and alcohol use disorder in Catalonia; to identify sociodemographic, substance, and clinical determinants associated with COVID-19 infection among SUD patients; and to compare the cumulative incidence of COVID-19 infection in the population with SUD with that of the general population. METHODS: A patient-based retrospective observational study was conducted. The study population comprised people who sought treatment for heroin, cocaine, cannabis, or alcohol use disorder in Catalonia in 2018 and 2019. We analysed cumulative incidence of COVID-19 (confirmed by PCR test) from 25 February to 31 December 2020. Additionally, we used a log-link binomial generalized linear model for COVID-19 infection, using the substance as the exposition, adjusting for sociodemographic and clinical variables. RESULTS: Of the 23,092 individuals who sought treatment for SUD, 38.15% were considered suspected cases of COVID-19, and 2.60% (95% CI = 2.41-2.82) were confirmed positive for COVID-19 by PCR test during the study period. Those who sought treatment for alcohol use (cumulative incidence of COVID-19 of 3% [95% CI = 2.70-3.34]) had a higher risk ratio than, those who sought treatment for heroin use (cumulative incidence of 1.94% [95% CI = 1.47-2.56]). Being born outside of Spain, living in an institutionalized residence, having HIV, and being in a high morbidity group were associated with higher risk of COVID-19 infection. Meanwhile, the cumulative incidence of COVID-19 in the general population, according to public COVID-19 test data, was 3.86% (95% CI = 3.85-3.87). CONCLUSION: This study did not find higher cumulative incidence of COVID-19 infection among people with SUD in Catalonia in 2020, despite the clinical vulnerability of this population and their social disadvantage. However, differences were seen in the cumulative incidence of COVID-19 according to the substance for which treatment was sought. For example, those with alcohol dependence had a higher rate than those dependent on heroin. Further studies are needed to determine the factors contributing to these differences.

Association between Cannabis Use Disorder and Mental Health Disorders in the Adolescent Population: A Cohort Study.

INTRODUCTION: According to the literature, early initiation to cannabis use and a dependent pattern of use are important risk factors for the development of mental health disorders. However, there are few cohort studies which look at the development of mental health disorders associated with cannabis use among young people with cannabis use disorder (CUD). The aim of the study was to determine the cumulative incidence of mental health disorders and the risk of developing mental health disorders among minors who commenced treatment for CUD in Catalonia during 2015-2019. METHODS: This was a retrospective fixed cohort study, matched for confounding variables, based on data from the Catalan Health Surveillance System. The exposed cohort comprised young people who entered treatment for CUD during 2015-2019 (n = 948) and who were minors on the date of commencing treatment. Matching was done with a paired cohort (n = 4,737), according to confounding variables. Individuals with a diagnosis of a mental health disorder prior to the study period were excluded. The cumulative incidence was calculated for mental health disorders for the exposed and the paired cohorts and stratified by type of mental disorder. Incidence rate ratios were estimated using the conditional Poisson model with robust variance, stratified by sex. RESULTS: The cumulative incidence for development of a mental health disorder was 19.6% in the exposed cohort and 3.1% in the paired cohort; with higher incidence among females (females 32.7%; males 15.8%). The exposed cohort had an 8.7 times increased risk of developing a mental health disorder than the paired cohort. The most frequent diagnoses were reaction to severe stress, adjustment disorder, and personality disorders. CONCLUSION: This study confirmed that the exposed cohort was at increased risk of developing mental health disorders compared to the paired cohort. To date, few studies have analyzed the association between cannabis use and the development of mental health disorders, considering cannabis dependence. Further studies should be undertaken considering CUD. In addition, more studies are needed to understand the factors that determine the development of CUD. Further research in these areas would contribute to the design of prevention strategies aimed at those young individuals with a higher risk of developing cannabis dependence and suffering its consequences.