cigarettes (often called e-cigarettes) has increased considerably among young people in the past 5 years. Use of e-cigarettes has been associated with higher rates of marijuana use, which is associated with several adverse health outcomes in youth. OBJECTIVE To characterize and quantify the association between e-cigarette and marijuana use among youth using a meta-analysis. DATA SOURCES PubMed, Embase, and Web of Science & ProQuest Dissertations and Theses were searched from inception to October 2018. A gray-literature search was also conducted on conference abstracts, government reports, and other sources. STUDY SELECTION Included studies compared rates of marijuana use among youth aged 10 to 24 years who had used e-cigarettes vs those who had not used e-cigarettes. Two reviewers independently assessed studies for inclusion; disagreements were discussed with a third reviewer and resolved by consensus. DATA EXTRACTION AND SYNTHESIS Data were extracted by 2 independent reviewers following Meta-analyses of Observational Studies in Epidemiology (MOOSE) reporting guidelines and pooled using a random-effects analysis. The Newcastle-Ottawa Scale was used to assess data quality and validity of individual studies. MAIN OUTCOMES AND MEASURES Adjusted odds ratios (AORs) of self-reported past or current marijuana use by youth with vs without past or current e-cigarette use. RESULTS Twenty-one of 835 initially identified studies (2.5%) met selection criteria. The meta-analysis included 3 longitudinal and 18 cross-sectional studies that included 128 227 participants. Odds of marijuana use were higher in youth who had an e-cigarette use history vs those who did not (AOR, 3.47 [95% CI, 2.63-4.59]; I 2 , 94%). Odds of marijuana use were significantly increased in youth who used e-cigarettes in both longitudinal studies (3 studies; AOR, 2.43 [95% CI, 1.51-3.90]; I 2 , 74%) and cross-sectional studies (18 studies; AOR, 3.70 [95% CI, 2.76-4.96]; I 2 , 94%). Odds of using marijuana in youth with e-cigarette use were higher in adolescents aged 12 to 17 years (AOR, 4.29 [95% CI, 3.14-5.87]; I 2 , 94%) than young adults aged 18 to 24 years (AOR, 2.30 [95% CI, 1.40-3.79]; I 2 , 91%). CONCLUSIONS AND RELEVANCE This meta-analysis found a significant increase in the odds of past or current and subsequent marijuana use in adolescents and young adults who used e-cigarettes. These findings highlight the importance of addressing the rapid increases in e-cigarette use among youths as a means to help limit marijuana use in this population.

Background: In Scandinavia, there is a strong tradition for research and quality monitoring based on registry data. In Denmark, Norway and Sweden, 63 clinical registries collect data on disease characteristics, treatment and outcome of various cancer diagnoses and groups based on process-related and outcome-related variables. Aim: We describe the cancer-related clinical registries, compare organizational structures and quality indicators and provide examples of how these registries have been used to monitor clinical performance, develop prediction models, assess outcome and provide quality benchmarks. Further, we define unmet needs such as inclusion of patient-reported outcome variables, harmonization of variables and barriers for data sharing. Results and conclusions: The clinical registry framework provides an empirical basis for evidencebased development of high-quality and equitable cancer care. The registries can be used to follow implementation of new treatment principles and monitor patterns of care across geographical areas and patient groups. At the same time, the lessons learnt suggest that further developments and coordination are needed to utilize the full potential of the registry initiative in cancer care.

Background: In contrast to most of the world, the cervical cancer screening programme continued in Denmark throughout the COVID-19 pandemic. We examined the cervical cancer screening participation during the pandemic in Denmark. Methods: We included all women aged 23-64 years old invited to participate in cervical cancer screening from 2015-2021 as registered in the Cervical Cancer Screening Database combined with population-wide registries. Using a generalised linear model, we estimated prevalence ratios (PR) and 95% confidence intervals (CI) of cervical cancer screening participation within 90, 180 and 365 days since invitation during the pandemic in comparison with the previous years adjusting for age, year and month of invitation. Results: Altogether, 2,220,000 invited women (in 1,466,353 individuals) were included in the study. Before the pandemic, 36% of invited women participated in screening within 90 days, 54% participated within 180 days and 65% participated within 365 days. At the start of the pandemic, participation in cervical cancer screening within 90 days was lower (pre-lockdown PR=0.58; 95% CI: 0.56-0.59 and 1st lockdown PR=0.76; 95% CI: 0.75-0.77) compared with the previous years. A reduction in participation within 180 days was also seen during pre-lockdown (PR=0.89; 95% CI: 0.88-0.90) and 1st lockdown (PR=0.92; 95% CI: 0.91-0.93). Allowing for 365 days to participation, only a slight reduction (3%) in participation was seen with slightly lower participation in some groups (immigrants, low education and low income). Conclusions: The overall participation in cervical cancer screening was reduced during the early phase of the pandemic. However, the decline almost diminished with longer follow-up time. Funding: The study was funded by the Danish Cancer Society Scientific Committee (grant number R321-A17417) and the Danish regions.

Background<br />In contrast to most of the world, the cervical cancer screening programme continued in Denmark throughout the COVID-19 pandemic. We examined the cervical cancer screening participation during the pandemic in Denmark.<br /><br />Methods<br />We included all women aged 23-64 years old invited to participate in cervical cancer screening from 2015-2021 as registered in the Cervical Cancer Screening Database combined with population-wide registries. Using a generalised linear model, we estimated prevalence ratios (PR) and 95% confidence intervals (CI) of cervical cancer screening participation within 90, 180 and 365 days since invitation during the pandemic in comparison with the previous years adjusting for age, year and month of invitation.<br /><br />Results<br />Altogether, 2,220,000 invited women (in 1,466,353 individuals) were included in the study. Before the pandemic, 36% of invited women participated in screening within 90 days, 54% participated within 180 days and 65% participated within 365 days. At the start of the pandemic, participation in cervical cancer screening within 90 days was lower (pre-lockdown PR=0.58; 95% CI: 0.56-0.59 and 1st lockdown PR=0.76; 95% CI: 0.75-0.77) compared with the previous years. A reduction in participation within 180 days was also seen during pre-lockdown (PR=0.89; 95% CI: 0.88-0.90) and 1st lockdown (PR=0.92; 95% CI: 0.91-0.93). Allowing for 365 days to participation, only a slight reduction (3%) in participation was seen with slightly lower participation in some groups (immigrants, low education and low income).<br /><br />Conclusions<br />The overall participation in cervical cancer screening was reduced during the early phase of the pandemic. However, the decline almost diminished with longer follow-up time.<br /><br />Funding<br />The study was funded by the Danish Cancer Society Scientific Committee (grant number R321- A17417) and the Danish regions.

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