Astudy by the Instituto de Saúde Pública da Universidade do Porto (ISPUP) analysed, for the first time, the trends in drowning mortality in Portugal between the years 1992 and 2019, based on national mortality data from the National Statistics Institute (INE) and modelled estimates from the “Global Burden of Disease” (GBD), an international study that provides information on the diseases with the highest incidence worldwide.
Over the 27 years studied, there were 6,057 deaths by drowning in Portugal, with a high number of deaths in people aged 65 or over. The researchers found a discrepancy in the mortality trend between the national data and the GBD data. While the INE data showed an increase in the drowning mortality rate in the last decade, the GBD estimates showed a decreasing trend in the number of deaths.
Although INE’s data provides more precise information than the GDB’s regarding the number of deaths by drowning in Portugal, the authors of the study believe that national information on the subject should be more detailed and therefore call for the creation of a National Integrated Register of Drowning and Aquatic Injuries that will allow the true impact of drowning (fatal and non-fatal) in Portugal to be characterised.
Drowning is the third leading cause of death from unintentional injury worldwide, estimated to have caused more than 236,000 deaths in 2019. In addition, non-fatal drownings (which do not result in death) often cause lifelong sequelae and are associated with a high social and economic impact.
In Portugal, there was, to date, no study that traced the panorama of drowning deaths in the country. The research Trends in drowning mortality in Portugal from 1992 to 2019: comparing Global Burden of Disease and national data is the first to do so.
The article, published in the journal Injury Prevention, aimed to “characterise fatal drowning in Portugal, comparing the data made available by the INE with that of the GBD, and to evaluate to what extent the GBD estimates mimicked the real data from the INE”, explains the first author of the study, Catarina Queiroga, researcher at ISPUP and collaborator of the associated Laboratory for Integrative and Translational Research in Population Health (ITR).
It was concluded that between 1992 and 2019, 6,057 drowning deaths occurred in Portugal. Overall, men were those who died most from drowning (69% of deaths) and there were a considerable number of deaths in people aged 65 and over (38%).
Overall, the research found that drowning deaths have been decreasing over the years. However, INE data showed an increase in the drowning mortality rate in the last decade, contrary to the GBD estimates that indicated a decreasing trend in the number of deaths from this cause.
“This is an interesting point of our study. We confirmed that the INE data gives us more accurate information than the GBD data. Through the national data, we can see that there is an increasing trend in the number of deaths by drowning, in recent years, in Portugal, whereas if we considered only the information from the GBD, we would think that there was a decreasing trend, and that everything was under control,” says Queiroga.
The researcher adds that “GBD mortality estimates are valuable where routinely collected data are not available. But because they smooth out variation, GBD estimates hide key prevention opportunities and make it difficult to identify vulnerable population groups.” With data from INE it was possible to identify a rise in drowning mortality in the last decade in the age group 20 to 34 years, with the increase in the number of deaths being more marked in people aged 65 and over. These are therefore the main priority groups in a drowning prevention strategy.
Although INE’s data provides more precise information than the GBD’s regarding the number of deaths by drowning in Portugal, the authors of the study believe that national information on the subject should be more detailed.
“National data does not have the desirable detail to understand the true impact of drowning in Portugal, as it only includes deaths, ignoring the human, economic impact and the consequences for the health system of non-fatal drowning,” explains Queiroga.
“Furthermore, the variables that are typically collected in the death certificate system do not include much data that is essential for a detailed characterisation of the problem, namely, the activity prior to the incident, the type of aquatic space involved, the impact of the use of alcohol, or of medication and drugs, the presence of life jackets, among others”, she adds.
Therefore, the authors of the study advocate the creation of a National Integrated Register of Drowning and Aquatic Injuries. This register should not be the exclusive responsibility of one organisation, but should have the collaboration of several bodies, namely maritime, defence, captains, hospitals, etc.
“The register we propose to create should integrate drowning and aquatic injury data, whether fatal or not, from the various entities involved in the register, and include incidents of recreational and occupational scope, and of any typology of intention (unintentional, intentional or undetermined),” says the ISPUP researcher.
The aggregated information would be useful for the development of a National Water Safety Plan for Portugal and for more targeted drowning prevention interventions for the populations most at risk.
This intention is in line with a guide published by the World Health Organization (WHO), which encourages all countries to collect data and study drowning in detail, so that it is possible to develop prevention strategies based on evidence and appropriate to the reality of each country, something that Portugal does not have.
Researchers Rui Seabra (CIBIO-InBIO and Biopolis), Richard Charles Franklin (College of Public Health, Medical and Veterinary Sciences, JCU, Australia), and Amy E Peden (School of Population Health, UNSW, Australia) also participated in the study.