start-ver=1.4 cd-journal=joma no-vol= cd-vols= no-issue= article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=2022 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Exchangeability of Measures of Association Before and After Exposure Status Is Flipped: Its Relationship With Confounding in the Counterfactual Model en-subtitle= kn-subtitle= en-abstract= kn-abstract=Background: The counterfactual definition of confounding is often explained in the context of exchangeability between the exposed and unexposed groups. One recent approach is to examine whether the measures of association (eg, associational risk difference) are exchangeable when exposure status is flipped in the population of interest. We discuss the meaning and utility of this approach, showing their relationships with the concept of confounding in the counterfactual framework.
Methods: Three hypothetical cohort studies are used, in which the target population is the total population. After providing an overview of the notions of confounding in distribution and in measure, we discuss the approach from the perspective of exchangeability of measures of association (eg, factual associational risk difference vs counterfactual associational risk difference).
Results: In general, if the measures of association are non-exchangeable when exposure status is flipped, confounding in distribution is always present, although confounding in measure may or may not be present. Even if the measures of association are exchangeable when exposure status is flipped, there could be confounding both in distribution and in measure. When we use risk difference or risk ratio as a measure of interest and the exposure prevalence in the population is 0.5, testing the exchangeability of measures of association is equivalent to testing the absence of confounding in the corresponding measures.
Conclusion: The approach based on exchangeability of measures of association essentially does not provide a definition of confounding in the counterfactual framework. Subtly differing notions of confounding should be distinguished carefully. en-copyright= kn-copyright= en-aut-name=SuzukiEtsuji en-aut-sei=Suzuki en-aut-mei=Etsuji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YamamotoMichio en-aut-sei=Yamamoto en-aut-mei=Michio kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YamamotoEiji en-aut-sei=Yamamoto en-aut-mei=Eiji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=3 en-affil=Okayama University of Science kn-affil= en-keyword=causality kn-keyword=causality en-keyword=causal inference kn-keyword=causal inference en-keyword=confounding kn-keyword=confounding en-keyword=counterfactual kn-keyword=counterfactual en-keyword=exchangeability kn-keyword=exchangeability en-keyword=target population kn-keyword=target population END start-ver=1.4 cd-journal=joma no-vol=31 cd-vols= no-issue=9 article-no= start-page=511 end-page=517 dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=20210717 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Emergency Dispatches for Suicide Attempts During the COVID-19 Outbreak in Okayama, Japan: A Descriptive Epidemiological Study en-subtitle= kn-subtitle= en-abstract= kn-abstract=Background: Hardships associated with the ongoing coronavirus disease 2019 (COVID-19) pandemic can affect mental health, potentially leading to increased risk of suicide. We examined the relationship between the COVID-19 outbreak and suicide attempts in Okayama, Japan using information from emergency dispatches.

Methods: This was a descriptive epidemiological study. We collected information on emergency dispatches in Okayama City and Kibichuo from March to August in 2018, 2019, and 2020 (n = 47,770 cases). We compared emergency dispatches and their demographic characteristics, especially focusing on suicide attempts, during these 3 years.

Results: The number of emergency dispatches in 2020 decreased compared with the previous 2 years, while the number and proportion of emergency dispatches related to suicide attempts increased. This increase was more pronounced among women and those aged 25-49 years. Among women aged 25-49 years, there was a cumulative total of 43 suicide attempts in 2018 and 2019 and 73 suicide attempts in 2020.

Conclusions: The number and proportion of emergency dispatches related to suicide attempts increased in 2020 compared with the previous 2 years, especially among women and those aged 25-49 years. This increase may be partly explained by hardships, such as economic losses or reduced social ties, during the COVID-19 outbreak. en-copyright= kn-copyright= en-aut-name=HabuHiroshi en-aut-sei=Habu en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakaoSoshi en-aut-sei=Takao en-aut-mei=Soshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=FujimotoRyohei en-aut-sei=Fujimoto en-aut-mei=Ryohei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NaitoHiromichi en-aut-sei=Naito en-aut-mei=Hiromichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NakaoAtsunori en-aut-sei=Nakao en-aut-mei=Atsunori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=YorifujiTakashi en-aut-sei=Yorifuji en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=2 en-affil=Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=3 en-affil=Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=4 en-affil=Department of Emergency and Critical Care and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=5 en-affil=Department of Emergency and Critical Care and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=6 en-affil=Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= en-keyword=COVID-19 kn-keyword=COVID-19 en-keyword=epidemiology kn-keyword=epidemiology en-keyword=emergency medical dispatch kn-keyword=emergency medical dispatch en-keyword=suicide kn-keyword=suicide END