Focus issue: Sudden cardiac arrestClinicalIncidence and etiology of sports-related sudden cardiac death in Denmark—Implications for preparticipation screening
Introduction
Sports-related sudden cardiac deaths (SrSCDs) are tragic occurrences that in most cases receive significant media attention. A proportion of these deaths are potentially preventable, which has fuelled an ongoing scientific debate on the merits and timeliness of preparticipation screening of competitive athletes. Preparticipation screening has already been implemented on different levels in many countries, with the most extensive preparticipation screening program mandatory in Italy since the early 1980s.1
Proponents for preparticipation screening argue that screening saves many lives,2 but also emotional and societal arguments such as the devastating effect of each SrSCD on a community and the problems that the death of a perceived healthy athlete as a role model present. Opponents emphasize the high number of disqualifications (false positives),3, 4 the impact on quality of life that a disqualification can have for the athlete, the loss of beneficial effects of sport on health, and the economic costs, and also question whether there is a proven effect of preparticipation screening.5, 6, 7, 8
A randomized study of preparticipation screening has never been reported and would be very hard to carry out because of the scale required. As a consequence, the evidence regarding the efficacy of preparticipation screening is based on observational studies. The most convincing data in favor of preparticipation screening are the significant decline in sudden cardiac death (SCD) cases among athletes in the Veneto region in Northern Italy after the implementation of the screening program.1
Few studies have provided numbers for SrSCD. The most accurate numbers probably also stem from Veneto, where the mandatory preparticipation screening with registration of all competitive athletes together with a prospective clinicopathologic investigation of SCD has allowed Corrado et al1 to provide numbers for SCD among athletes. Based on 14 cases, they have reported an overall annual incidence rate of 4.19 per 100,000 athlete person-years in the prescreening period of 1979 to 1981. In contrast, incidence rates from U.S. data have been consistently lower.9, 10, 11 The causes of SCD among athletes also differ among studies, with a high proportion being caused by hypertrophic cardiomyopathy (HCM) in the United States9 and by arrhythmogenic right ventricular cardiomyopathy (ARVC) in the screened population in Italy.12
In Denmark, no systematic screening of athletes has been in place during or before the study period, but due to requirements from among others the Union of European Football Associations screening of a small group of elite athletes has been carried out recently.
Before implementing preparticipation screening of a wide array of elite athletes in Denmark, we wanted to investigate the magnitude of the problem and the potential effect of screening. We thus undertook a retrospective nationwide analysis of all deaths to estimate incidence and etiology of SrSCD among individuals ages 12 to 35 years who died in Denmark in 2000 to 2006. Furthermore, we compared our national data with data from the United States and Italy.
Section snippets
Methods
The design of the study was a nationwide retrospective study. The death certificate contains 1) Cause of death section consisting of 4 lines listing a chain-of-events of diseases and/or injuries that caused the death. 2) Other significant diseases contributing to the death. 3) Mode of death section. 4) Operation performed and autopsy status. Autopsy status can be ticked as forensic autopsy, hospital autopsy, no autopsy (forbidden) or no autopsy, other reason. 5) Supplemental information field
Review of death certificates
During the study period, there were 5,865 deaths within the age group, but in 203 cases, concerning either foreigners or Danish citizens dying outside of Danish borders, no death certificates were issued. We thus received 5,662 death certificates, and after excluding 53 death certificates due to missing data, 5,609 death certificates were reviewed. A flow chart of the process is shown in Figure 1.
Athlete background population
According to the National Danish Health and Morbidity Study, 10.9% of the Danish population in the
Discussion
We report a study of all deaths for decedents ages 12 to 35 years in the period 2000 to 2006 in Denmark with the aim of identifying all cases of SrSCD. We thoroughly examined a total of 5,662 death certificates and found 15 cases of SrSCD, amounting to an incidence rate of 1.21 per 100,000 athlete person-years.
We used a novel approach to chart the incidence of SrSCD compared with other studies; instead of relying on reporting either in the media (U.S.9) or from hospitals and pathological
Conclusion
In Denmark, SrSCD in the young is a rare occurrence, with an incidence rate of 0.13 per 100,000 person-years in the general population and 1.21 per 100,000 athlete person-years. This is comparable to the Italian postscreening era incidence rate of 0.87 per 100,000 athlete person-years, and lower than the Danish incidence rate of SCD of 3.76 per 100,000 person-years in the general population. These data imply that preparticipation screening of athletes is likely to be of low value in Denmark.
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Supported by the Foundation of 17-12-1981, the John and Birthe Meyer Foundation, the Arvid Nilsson Foundation, the Danish National Research Foundation, the Danish Heart Foundation (07-10-R60-A1751-B743-22412), the Research Foundation at the Heart Centre, Rigshospitalet, the Research Foundation of Bispebjerg Hospital, and Bønnelykkefonden.