Unintentional drowning: Role of medicinal drugs and alcohol

The unintentional drowning rate in Finland is a cause for concern – it is significantly greater than that in most Western European countries and other high-income countries. In fact, great emphasis has already been drawn to the association of drowning with alcohol consumption. A retrospective study recently published in BMC Public Health, however, is different to those presented in the past - this also establishes the association with different types of psychotropic drugs.

Unintentional drowning is a global concern, which encompasses all cases of drowning and their associated outcomes – morbidity, no morbidity, and death. As a water-centered society, Finland faces one of the highest rates of this in the developed world. In fact, an extensive population-based study (1970-2000) revealed over 9000 unintentional drownings, and named alcohol consumption as a key risk factor.

In their article recently published in BMC Public Health, Pajunen et al studied data from a nationwide survey provided by the Laboratory of Forensic Toxicology at the University of Helsinki. Already knowing that psychotropic drugs can impact psychomotor functioning and cognition, their aim was to determine if this was another potential risk factor associated with unintentional drowning. The dataset they used spanned over a 10-year period (2000-2009) and included 2,828 cases of fatal drownings; however, some cases were excluded from this study based on the manner of drowning e.g. accident, suicide, homicide, undetermined intent.

Two of the authors carried out post-mortem toxicology for the 1,746 eligible cases, with 100% of these tested for alcohol, and 91.5% subjected to a full toxicological analysis to test for both alcohol and other drugs.

As part of this testing, two of the authors of this paper used a well-established 6-grade scale to independently evaluate the contribution of each drug to fatal drowning, and then a summary score for each drug. The scoring process also considered factors such as drug concentration, concentration-dependent impairment, post-mortem changes and redistribution of drugs.

The data reinforced the previously reported concentration-effect relationship between alcohol and drowning, which make it almost undeniable that alcohol consumption contributes to drowning during aquatic activities.

The impact of medicinal drugs on unintentional drowning has been less well studied, thus this article may be considered unique by evaluating both the individual and combined effects of several drugs. The findings suggest that psychotropic drugs may also play a significant role in unintentional drowning, as it became apparent that they contributed to up to 14.6% of cases, whether taken independently or in addition to alcohol.

More specifically, the analysis revealed over 70 different psychotropic drugs, with benzodiazepines as the most commonly taken. This result might be most relevant to health professionals and their patients – as this class of drug is already known to affect cognitive and psychomotor skills, appropriate caution and warning is imperative for those patients engaging in aquatic activities; especially those likely to consume alcohol.

Furthermore, among the 10 most common psychoactive and non-psychoactive drugs detected in the case samples, several may contribute to fatal drowning by causing drug-induced long-QT syndrome. This is a condition causing an abnormal heart rhythm, thereby affecting the normal pumping of blood in the body.

Unintentional drowning is an issue which has warranted nation-wide drowning-prevention campaigns already.  Whilst the role of alcohol in such cases is fairly well studied, that of medicinal drugs has only just been considered in detail, and further investigation is still required to determine the mechanism of drug actions involved. In light of this, however, this study suggests that appropriate information should be conveyed to the public to ensure that they are aware of the risks associated with their medical status, lifestyle, and behaviour.

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