Health related behaviour patterns in Denmark during the first COVID 19 wave

Objective The COVID-19 pandemic raised concerns about how lockdowns affected health-related behaviours. This study aimed to identify patterns of health-related risk behaviours in Danish adults during the first pandemic wave. Methods We used data from the Danish part of the Collaborative Outcomes study on Health and Functioning during Infection Times (COH-FIT), collected in May 2020 with recruitment through social media and newsletters. Responses were weighed against a Danish representative 2021 sample. Self-reported health-related behaviours were dichotomised into high-risk or not, and Latent Class Analysis was used to identify behavioural subgroups based on sedentary behaviour, media use, substance use, and harmful behaviours. We also examined pre- to during-pandemic changes in behaviour and subgroup demographics. Results Five behavioural subgroups were identified. The largest group (53%) reported low to modest levels of high-risk behaviours. Two medium-sized groups included one (23%) with high media use, tobacco use, and aggression/self-harm, and another (18%) with low levels of most high-risk behaviours but moderate cannabis use and relatively high aggression. Two smaller high-risk groups included one (3%) with aggression, alcohol use, and physical inactivity, and another (2%) with smoking, cannabis, and gaming. Increases from pre-pandemic levels were most common in social media use (47%), TV viewing (46%), and internet use (41%). Conclusions These findings suggest the pandemic intensified pre-existing risk behaviours rather than introducing new ones. Public health strategies should consider behaviour clustering to better support vulnerable subgroups. While limited by a cross-sectional, retrospective design, the study contributes valuable insight into behaviour patterns during societal disruptions.