Table 1 Variables in the Danish Drowning Cohort year 2024

Patient information

 Identifier

 [cpr_nummer]

 (PEMR)

The patient’s civil registration number is unique and is used in Denmark as an identification number for all Danish citizens. It consists of 10 digits reflecting the birth date. The civil registration number is used for data collection and linkage with other registries, not reporting. Extracted from [CPR_nummer] in the PEMR

Integer

 Prehospital description

 [free_text_field]

 (PEMR)

The prehospital description contains the EMS professional’s case description

Free_text_field.

 Sex

 [koen_cpr]

 (PEMR)

Sex. Extracted from [Koen] in the PEMR

Categorical, dichotomous. Male; Female

 Age

 [alder]

 (PEMR)

Age in years at the drowning incident. Extracted from [Alder] in the PEMR

Integer. Age in years

 Incident date

 [dato]

 (PEMR)

Date of the drowning incident. Manually validated from [incidentcreatedtime / AMKModtagetDateTime] in the PEMR

Date. YYYY-MM-DD

 Incident time

 [tid]

 (PEMR)

Time of the drowning incident. Manually validated from [incidentcreatedtime / AMKModtagetDateTime] in the PEMR

Time. hh: mm

 Activity

 [aktivitet]

 (manual validation)

Activity at the time of the incident. “Swimming/bathing” included all forms of playing, bathing, and swimming. “Boating activity” included activities on a boat in open water, including fishing from a boat. However, if the boat was in port, the activity was defined as “Harbour activity”. “Diving” was used for free or scuba diving. “Water sports” was used for incidents involving swim practice, kayaking, water polo, surfing, etc. Manually validated from [free_text_field] in the PEMR

Categorical, nominal. Swimming/bathing; Diving; Recreational fishing; Operating vehicle; Water sports (specify); Attempted suicide; Walking; Biking; Boating; Rescuing; Urinating

 Suspected alcohol or drug intoxication

 [alcohol_drug]

Alcohol and drug intoxication include suspicion of intake by any indications such as alcohol odour, empty bottles, self-reported intake, etc

Categorical, dichotomous. No; Yes

 Precipitating event

 [forudgaaende]

 (manual validation)

Precipitating events with a possible causal relation to the drowning incident. “Unaware of surroundings” was used for patients falling unintentionally into the water where no other precipitating event could be selected. “Cold water immersion” was used for winter bathing specifically. Manually validated from [free_text_field] in the PEMR

Categorical, nominal. Jumping; Psychologically impaired; Suspected medical cause; Submerged vehicle; Flood, Panic attack/Hyperventilation; Breath holding; Man overboard; Capsized; Pushed into water or other type of violence; Walking on ice; Unaware of surroundings; Cold water immersion; Waterslide; Other (specify)

Scene information

 Water temperature

 [vand_tp]

 (Danish Meteorological Institute)

Icy or non-icy water. Manually validated based on incident coordinates linked with data from the Danish Meteorological Institute.

Categorical, dichotomous. Non-icy; Icy

 Witnessed drowning

 [bevidnet_drukning]

 (manual validation)

Witnessed drowning incident (did someone see the person going underwater? ). Manually validated from [Givetaf / free_text_field] in the PEMR.

Categorical, nominal. Unwitnessed; Witnessed by a bystander; Witnessed by a lifeguard; Witnessed by police or EMS

 Rescuer

 [redningsperson]

 (manual validation)

Rescuer characteristics (who rescued the patient? ). Manually validated from [free_text_field] in the PEMR.

Categorical, nominal. Self-rescue; Member of the public; Professional; Unknown

 Highest level of EMS unit

 [ems_type]

 (PEMR)

Highest level of EMS competency. Extracted from [taskEmsUnitType / Akutlaegeinvolveretfoerankomstti / Laegemed / Laegeledsagelseundertransport / laege_bil_helikopter / free_text_field] in the PEMR.

Categorical, ordinal. Ambulance; Paramedic; Prehospital ground-based EMS physician; Prehospital HEMS physician

 Type of response to patient

 [respons_ud]

EMS response to the patient. A: Life-threatening or potentially life-threatening condition, immediate response required; B: Urgent, but not life-threatening. Extracted from [respons] in the PEMR.

Categorical, dichotomous. A; B

 Type of response to hospital

 [respons_hjem]

 (PEMR)

EMS response to the hospital: A: Life-threatening or potentially life-threatening condition, immediate response required; B: urgent, but not life-threatening condition. Extracted from [koerselsformretur] in the PEMR.

Categorical, ordinal. A; B

 EMS GCS

 [GCS]

 (PEMR)

First GCS score at the first EMS assessment. GCS score ranges from 3 to 15. Extracted from [GlasgowComaScale_Oejne / GlasgowComaScale_Verbal / GlasgowComaScale_Motoriskrespons / GlasgowComaScore / GlasgowComaScore_first / GlasgowComaScore_firstDT] in the PEMR.

Integer. GCS score

 Out-of-hospital cardiac arrest

 [OHCA]

 (PEMR)

Out-of-hospital cardiac arrest was defined as unresponsive and not breathing normally at any time prehospital. Extracted from [Hjertestop-registreringer] in the PEMR.

Categorical, dichotomous. No; Yes

 Witnessed cardiac arrest

 [bevidnet_OHCA]

 (PEMR)

Witnessed cardiac arrest (did someone see the person collapse? ). Extracted from [Givetaf / Bevidnet / Hjertestopovervaeret / free_text_field] in the PEMR.

Categorical, nominal. Unwitnessed; Witnessed by a bystander; Witnessed by a lifeguard or EMS

 Bystander CPR

 [bystander_hlr]

 (PEMR)

Cardiopulmonary resuscitation performed by bystander (non-EMS person). Extracted from [Behandling / StartHLR / free_text_field] in the PEMR.

Categorical, dichotomous. No; Yes

 Bystander defibrillation

 [ems_stoed]

 (PEMR)

Defibrillation performed by bystander (non-EMS person). Extracted from [Behandling / Defibrillering / Defibrillering_2] in the PEMR.

Categorical, nominal. No; Yes, public access AED; Yes, other AED

 EMS initial cardiac rhythm

 [rytme]

 (PEMR)

The initial cardiac rhythm from a cardiac monitor. Extracted from [rytme / Hjerterytme] in the PEMR.

Categorical, nominal. VF; pVT; PEA; Asystole; Other

 EMS SpO2

 [ems_sat]

 (PEMR)

Devices are necessary to measure vital signs (first, lowest). The maximum SpO2 is 100%. Extracted from [SpO2_first / SpO2_firstDT / SpO2_mon_first / SpO2_mon_firstDT / SpO2_mon_lowest / SpO2_mon_lowestDT / SpO2_lowest / SpO2_lowestDT] in the PEMR.

Integer. Peripheral capillary oxygen haemoglobin saturation (SpO2)

 EMS respiratory rate

 [ems_rf]

 (PEMR)

Devices are necessary to measure vital signs (first, highest). Extracted from [RespFrekvens_first / RespFrekvens_firstDT / RespFrekvens_mon_first / RespFrekvens_mon_firstDT / RespFrekvens_highest / RespFrekvens_highestDT / RespFrekvens_mon_highest / RespFrekvens_mon_highestDT] in the PEMR.

Integer. Respiratory rate (BPM)

 EMS systolic blood pressure

 [ems_sbt]

 (PEMR)

Devices are necessary to measure vital signs (first). Extracted from [NInvSysBlodtryk_first / NInvSysBlodtryk_firstDT / NInvSysBlodtryk_mon_first / NInvSysBlodtryk_mon_firstDT] in the PEMR.

Integer. Blood pressure (mmHg)

 EMS diastolic blood pressure

 [ems_dbt]

 (PEMR)

Devices are necessary to measure vital signs (first). Extracted from [NInvDiaBlodtryk_first / NInvDiaBlodtryk_firstDT / NInvDiaBlodtryk_mon_first / NInvDiaBlodtryk_mon_firstDT] in the PEMR.

Integer. Blood pressure (mmHg)

 EMS heart rate

 [ems_hr]

 (PEMR)

Devices are necessary to measure vital signs (first). Extracted from [Hjertefrekvens_first / Hjertefrekvens_firstDT / Hjertefrekvens_mon_first / Hjertefrekvens_mon_firstDT / Puls_first / Puls_firstDT / Puls_mon_first / Puls_mon_firstDT] in the PEMR.

Integer. Heart rate (BPM)

 EMS temperature

 [ems_tp]

 (PEMR)

Devices are necessary to measure vital signs (first, lowest). Extracted from [Temperatur_first / Temperatur_firstDT / Temperatur_lowest / Temperatur_lowestDT] in the PEMR.

Decimal. Temperature (degrees Celsius)

 Respiratory exam finding

 [resp]

 (PEMR)

The severity of lung injury immediately after the drowning process was stopped. Extracted from [free_text_field / B_Respiration / SekundaerB / SekundaerBAndet / Respiration / Respiration_2 / Respiration_3 / Aandedraet / Traume_aandedraetsfunktion] in the PEMR.

Categorical, nominal. One or more: Normal lung examination; Patient coughing; Unilateral rales; Bilateral rales; Increased work of breathing

 Latitude

 [lat]

 (manually validated)

Latitude of the drowning incident. Extracted from incident road name [AnkomstVejnavn], road number [AnkomstVejnummer], and incident postal code [AnkomstPostnr] in the PEMR.

Decimal

 Longitude

 [lon]

 (manually validated)

Longitude of the drowning incident. Extracted from incident road name [AnkomstVejnavn], road number [AnkomstVejnummer], and incident postal code [AnkomstPostnr] in the PEMR.

Decimal

 Type of liquid

 [vaeske]

 (manual validation)

Type of liquid. Manually validated from [free_text_field] in the PEMR, latitude [lat], and longitude [lon].

Categorical, nominal. Freshwater; Saltwater; Water containing chemicals; Other

 Body of water

 [lokation]

 (manual validation)

Body of water. The location type “Natural waters " was used for all coastlines, open oceans, creeks, streams, lakes etc. The location type “Other” included drowning incidents in wells, manure stores, etc. Manually validated from [free_text_field] in the PEMR, latitude [lat], and longitude [lon].

Categorical, nominal. Bathtub/Spa/Hot tub; Swimming pool (public); Swimming pool (private); Harbour; Natural waters; Other (specify) ^c

 Population density

 [befolknings_taethed]

 (manual validation)

The municipal population density was used to estimate population density at the site according to the EUROSTAT degree of urbanisation system (DEGURBA) [54]. Manually validated from [free_text_field] in the PEMR / latitude [lat] and longitude [lon].

Categorical, ordinal: Low density; Intermediate density; High density

Time points and intervals from EMS data

 Time call

 [tid_opkald]

 (PEMR)

Time of first call to the Emergency Medical Dispatch Centre. Extracted from [AMKModtagetDateTime] in the PEMR.

Time. hh: mm

 Time EMS arrival

 [tid_ankomst]

 (PEMR)

Time of first EMS assessment. Extracted from [Patientkontakttid / AnkomstOpgaveDT] in the PEMR.

Time. hh: mm

 Response time

 [tid_respons]

 (manually validated)

Time from first call to the Emergency Medical Dispatch Centre [tid_opkald] until time of EMS arrival [tid_ankomst].

Time. hh: mm

 ROSC time

 [tid_ROSC]

 (PEMR)

Time of first Return Of Spontaneous Circulation. Extracted from [ROSC_tid] in the PEMR.

Time. hh: mm

 Submersion duration

 [tid_submersion]

 (manual validation)

Derived from when the face was first seen underwater to the time of removal from the water. If no exact times are provided, best judgment will be used according to the USFD. Manually validated from [free_text_field] in the PEMR.

Categorical, ordinal. <6 min; <11 min; <16 min; <20 min; <25 min; ≥25 min

EMS treatment, including resuscitation factors

 EMS CPR

 [ems_hlr]

 (PEMR)

Cardiopulmonary resuscitation performed by EMS. Extracted from [HLR / StartafHLRafmandskab] in the PEMR.

Categorical, dichotomous. No; Yes

 EMS defibrillation

 [ems_stoed]

 (PEMR)

Defibrillation performed by EMS. Extracted from [Defibrillering_2 / GavPraehospitalDC_stoedS] in the PEMR.

Categorical, dichotomous. No; Yes

 Airway support

 [a_support]

 (PEMR)

Highest level of airway support performed by EMS. Extracted from [Sugning / Nasal airway / Tungeholder / Larynxmaske / Intubation / Oralintubation / Noedtrakeotomi / free_text_field]] in the PEMR.

Categorical, ordinal. Suction; Nasopharyngeal airway; Oropharyngeal airway; Supraglottic airway; Endotracheal intubation; Surgical airway

 Ventilatory support

 [b_support]

 (PEMR)

Highest level of ventilatory support performed by EMS. Extracted from

[Ilt_naesebrille / Ilt_nebulisator / Ilt_hudsonmaske / CPAP_ASB / Naaledekompression / Pleuradraen / Respiration_4 / Pleuradraen_2 / Maskeventilation / Ventilation_2 / free_text_field] in the PEMR.

Categorical, ordinal. Nothing; Nasal cannula; Non re-breather mask; Venturi mask; Non-invasive (CPAP); Needle decompression; Chest drain; Bag-mask ventilation; Invasive Mechanical ventilation

 Circulatory support

 [c_support]

 (PEMR)

Highest level of circulatory support performed by EMS. Extracted from [Perifertvenekateter / Intraossoeskanyle / Tourniquet / NatriumClorid / Noradrenalin / Dopamin / Efedrin / Isoprenalin / Phenylephrin / Mekaniskbrystkompression / ErderanvendtkompressionsmaskineS / free_text_field] in the PEMR.

Categorical, nominal. One or more. Nothing; intravenous access; Intraosseous access; Tourniquet; Fluids; Vasopressors; Inotropes (Norepinephrine, Dopamine); Chest compression device

 Hypothermia

 [hypotermi]

 (PEMR)

Treatment for suspected hypothermia. Extracted from [Kuldeindpakning] in the PEMR.

Categorical, dichotomous. No; Yes

 Spinal motion restriction

 [smr]

 (PEMR)

Spinal motion restriction performed with or without equipment to stabilise a suspected spinal injury performed by EMS. Extracted from [Halskrave / Spinalstabilisering / Vacuummadras] in the PEMR.

Categorical, dichotomous. No; Yes

 Prehospital diagnosis

 [diagnose_prehos]

 (PEMR)

Prehospital diagnosis. Extracted from [CNS / Respiration / Kredsloeb / Abdomen / Bevaegeapparatet / Hormon / Psykiatri / Socialt / Andet] in the PEMR.

Categorical, nominal. One or more

Outcome measures

 Prehospital mortality

 [doed_prehos]

 (PEMR)

Declared dead prehospital. Extracted from [Afsluttetpaastedet / Afsluttetpaastedet_2 / Fortsathjertestop / Behandlingsprioritet / free_text_field] in the PEMR.

Categorical, dichotomous. Dead; Alive

 30-day survival

 [overl_30d]

 (Civil Personal Register)

Survival status 30 days after the drowning incident collected from the Civil Personal Register via the patient’s civil registration number.

Categorical, dichotomous. Dead; Alive

 Status at hospital admission

 [status_hospital]

 (PEMR)

Patient’s status at hospital admission. Extracted from [Patientenstilstandvedankomsttilh / ROSC] in the PEMR.

Categorical, nominal. Terminated CPR; Ongoing CPR; ROSC, unconscious; ROSC, conscious

 Non-conveyance

 [afsluttet_paa_sted]

 (PEMR)

Final decision not to transport the patient to a healthcare facility. Extracted from [Afsluttetpaastedet / Afsluttetpaastedet_2] in the PEMR.

Categorical, dichotomous. No; Yes

 Severity of drowning injury

 [alvorsgrad_drukning]

 (manual validation)

Highest level of drowning injury according to the categorisation of severity of drowning [55]. “Dead body” includes obvious clinical signs of irreversible death (decapitation, decomposition, postmortem lividity, postmortem rigidity). Manually extracted from [free_text_field / Afsluttetpaastedet / Afsluttetpaastedet_2] in the PEMR.

Categorical, ordinal. Rescue; Grade 1; Grade 2; Grade 3; Grade 4; Grade 5; Grade 6; Dead body

 Severity of respiratory impairment

 [alvorsgrad_resp]

 (manual validation)

Highest level of respiratory impairment according to the categorisation of severity of respiratory impairment [31]. Manually validated from [B_Respiration / SekundaerB / SekundaerBAndet / free_text_field] in the PEMR.

Categorical, ordinal. Mild; Moderate; Severe