Risk factors associated with fatal vs non-fatal drowning in Denmark: A nationwide cohort study from 2016 to 2023

OBJECTIVES: Identifying and analysing non-fatal and fatal drowning incidents from the nationwide population is essential to inform targeted and evidence-based drowning prevention strategies. This study aimed to establish a national epidemiological profile of non-fatal and fatal drowning patients in Denmark and identify risk factors associated with 30-day survival. STUDY DESIGN: Registry-based, national cohort study based on prehospital electronic medical records from 2016 to 2023. METHODS: This study analysed a national cohort of drowning patients attended by the Danish emergency medical services from 2016 to 2023. Patients were captured through drowning-specific keywords in the prehospital electronic medical record, followed by manual validation. Cumulated incidence rates were reported per 100000 person-years with 95% confidence intervals (CIs). Risk factors associated with 30-day survival were identified using multivariable logistic regression adjusted for sex, age group, and witnessed incident status, presented as adjusted odds ratios (aORs) with 95% CIs. RESULTS: Drowning-specific keywords identified 1664 patients between 2016 and 2023. Complete 30-day follow-up was available for 1483/1664 (89%) patients: 711 non-fatal and 722 fatal drowning patients. The cumulated incidence rates for fatal and non-fatal drowning were 3·58 per 100000 person-years (95% CI, 3·41-3·75). The cumulated incidence rate for non-fatal drowning declined significantly but remained relatively unchanged for fatal drowning over the study period. Risk factors associated with a lower 30-day survival included age ≥18 years (aOR 0·06 [95% CI, 0·03-0·11]), unwitnessed incident (aOR 0·18 [95% CI, 0·13-0·26]), and submersion times exceeding 5 min (aOR 0·01 [95% CI, 0·00-0·02]). Compared to public pools, lower 30-day survival was significantly associated with drowning in natural waters (aOR 0·13 [95% CI, 0·06-0·63]), harbours (aOR 0·25 [95% CI, 0·11-0·53]), and private places (aOR 0·13 [95% CI, 0·05-0·32]). CONCLUSIONS: This national epidemiological profile suggested that age ≥18 years, unwitnessed incident, and submersion times exceeding 5 min were associated with a lower survival at 30-day follow-up. Furthermore, survival after drowning differs by location, emphasizing the importance of tailored prevention strategies.