Table 4 The USFD parameters used in 5 or more of the 14 USFD drowning publications

 Victim identifier (Core)

Not related to a conclusion

 Gender (Core)

Most drowning victims are male (57–100%) in 12 publications [3,4,5,6, 8,9,10,11,12,13, 15, 16]. In one publication 35% of the victims are male [7]. In one publication the distribution is unclear due to a contradiction in the reporting of this parameter [14].

 Precipitating event (Core)

The most frequently reported precipitating events are motor vehicle or boating accidents, and swimming [6, 8, 12,13,14].

 Pre-existing illness (Supplemental)

Pre-existing illness is either not reported or not linked to outcome in any of the publications [3, 5, 6, 8, 12].

 Body of water (Core)

Drowning occurs mostly (66–100%) in natural bodies of water such as rivers, lakes and canals in eight publications [3, 5,6,7,8, 10, 12,13,14, 16]. Two publications report that drowning occur predominantly (52 and 95%) in private or public pools [9, 15]. Another publication has only included drowning in swimming pools [11].

 Water/liquid type (Supplemental)

Seven publications predominantly (84–100%) report fresh water drownings [3, 5,6,7,8, 10, 16]. In one publication drowning in roadside ditches, canals and retention ponds are reported as the predominant water sources, however salinity was not determined [12]. In one publication all drownings occurred in salt water [14]. In the two publications where most drownings occurred in pools, the salinity of these pools was not specified [9, 15].

 Unconscious when removed from water (Core)

Four publications report that 83–100% of the victims were unconscious when removed from the water [3, 5, 9, 16]. In two publications a minority were unconscious [6, 13]. Two publications show an equal distribution [12, 14].

 Method of CPR (Supplemental)

One publication only reported that the victims were resuscitated according to guidelines [16]. Five publications described in more detail how resuscitation was performed, based on which it seems that international guidelines were followed [4,5,6, 11, 14]. One of these publications reported that in 10% resuscitation was not performed according to guidelines (tapping on back, rubbing abdomen, pressing water out of lungs etc.) [6]. Another one of these publications described the use of abdominal trusts in and outside the water [11].

 EMS called (Core)

Calling the EMS is directly or indirectly reported in 11 publications but as such provides no relevant information.

 EMS vehicle dispatched (Supplemental)

Dispatch of the EMS is directly or indirectly reported in ten publications but as such provides no relevant information.

 Initial vital signs (Core)

Two publications directly or indirectly reported that all victims were in cardiac arrest [3, 16]. One publication reported that all victims had a Glasgow Coma Scale of 3 [5]. One publication reported that 53% of the victims were in cardiac arrest [14]. One publication described that the information was available in 0.3% of the victims but made no further specifications [6].

 Neurological status (Core)

Two publications reported that all victims had a Glasgow Coma Scale of 3 [3, 5]. One of these publications also reported fixed dilated pupils for all patients [3]. One publication reported that 16% of the victims were unconscious and 84% were conscious [6]. One publication reported that four patients (50%) were comatose of which two had fixed dilated pupils with diffuse flaccid paralysis. This same publication also reported a mean initial Glasgow Coma Scale of 10.4 [12]. In one publication this information was indirectly available because all were in cardiac arrest [16].

 Airway and ventilation requirements (Core)

All seven publications that reported this parameter only globally described it, which provided no real relevant information [3, 7, 8, 12, 14,15,16].

 Complicating illnesses (Supplemental)

Six publications report complicating illnesses such as pneumonia, acute respiratory distress syndrome, pancreatitis, rhabdomyolysis, disseminated intravascular coagulation acute renal failure, multiple organ failure and septic shock [3, 5, 7, 9, 12, 16]. In one of these publications extubation stridor, minor neurologic deficits and corneal ulceration are reported which all are resolved at the time of discharge [9].

 Alive or dead (Core)

Survival is good (16–93%) in most studies [3,4,5,6,7,8,9,10,11,12, 14, 15]. In one study only 5% of the victims survived [16]. One publication only reports non-fatal drowning [13].

 Neurological outcome at hospital discharge (Core)

In four publications 7–20% had a (Paediatric) Cerebral Performance Scale/Category (P)CPC score of one to two [3, 5, 7, 8]. In one publication 85% of the patients had a CPC score of one to two [4]. In one publication 84% of the patients do not have any neurological complications, while 5.3% have irreversible neurological sequellae [9]. In one publication 11% of the patients have a (P)CPC score of three or less 1 year after the drowning incident [10]. In one publication hypoxic encephalopathy is reported in one victim (13%) [12]. One publication described a median Functional Independence Measure of 115 (range 51–121) and a median extended Glasgow Coma Scale score of 4 (range 3–7) after 6 months [14]. In one publication two victims (5%) survived to hospital discharge of which one had a CPC score (at discharge and at 6 months later) of one and one had a CPC score of three [16].

 Cause of death (Supplemental)

Five publications described causes of death such as multi organ failure, septic shock, cardiac arrest, respiratoy failure, severe brain injury and brain death [3, 7, 10, 12, 16].