Discussion
Different methodologies have yielded conflicting estimates of the death rates during marathons. Large surveys of multiple marathons have suggested that the death rate is just under 0.70/100 000 finishers (0.67). Detailed studies of a small number of events have suggested the rate is higher at just over 1.00/100 000 finishers (1.04), although it should be noted that the death rate was higher in the three best studied marathons—the London Marathon and the MCM and TCM. The MCM has the highest reported rate of death at 1.94/100 000 finishers. In contrast, in 12 years in Japan, a nation with a rich running tradition, recently it was reported that there have been no deaths at the marathon distance, but the precise number of runners was not included, precluding its inclusion in this analysis.18 Women appear to be at lower risk than men, and most fatalities occur in the final miles of the race. What is clear from this analysis is that the chances of dying during a marathon are very low.
It is not surprising that the death rates are slightly higher in reports of specific marathons, where the reports have been produced by the team directly responsible for healthcare for these events. They will be aware of all the medical problems faced, and it is almost inconceivable that a death would be missed. The larger studies of multiple events have relied on direct contact with race organisers, with incomplete responses and searches of relevant press reports. Although deaths in high-profile events are now widely reported, this is not always the case for smaller events. Furthermore, it is more likely that deaths will be missed compared with the studies which have focused on specific marathons, and therefore these papers have the potential to underestimate the true fatality rate. One potential solution to help understand the problem in more detail would be to create a centralised database with voluntary reporting of deaths, although it would require funding and oversight. Depending on its construction it could yield more precise information about the numbers and aetiologies of deaths.
Looking at the causes of death is important for marathon organisers. The most common cause of death that was reported was IHD, which predominantly affected men over 40. Other cardiac causes of death included HCM and anomalous coronary arteries. It is unknown how many had antecedent symptoms, but training programmes typically do not put runners under the same sort of stress as they will experience on marathon race day, with most ‘long runs’ peaking at 20 miles and at a slower pace. The stress of the marathon releases a number of inflammatory biomarkers and there is also evidence of hypercoagulability, creating a situation in which plaque rupture and subsequent coronary thrombosis is more likely.19 Interestingly, it has been recognised recently that strenuous exercise is associated with more prevalent coronary artery calcification, but this is not associated with increased mortality.20 Some have argued that aspirin should be considered in those likely to be at higher risk of myocardial infarction.21
How to screen for cardiac problems in advance? An ECG can be helpful and is often advised but does not reliably pick up either IHD or HCM. An echocardiogram can diagnose HCM reliably. A cardiac CT can pick up asymptomatic coronary disease or anomalous coronary arteries. Judging from the lack of symptoms during training an exercise test or stress echocardiogram may be falsely reassuring.
Hyponatraemia is a more common cause of death in younger marathon participants. A degree of hyponatraemia is common in marathon runners.13 Its aetiology is probably more complex than might be assumed, although the principal cause is drinking to excess.22 The consensus advice is that marathon runners should ‘drink to thirst.’23 Sodium supplementation remains controversial.24
Heatstroke is a concern to marathon organisers but appears to be a relatively rare cause of death (see online supplementary appendix tables 1 and 8). Some people appear more susceptible than others. Recommendations to prevent heat-related illness include avoiding participation if there has been a recent fever, drinking appropriately and organisers can provide facilities for cooling athletes; run-through showers, for example, are common.25
The observation that most deaths occurred in the latter stages of the races is important for race organisers. There are always finite resources and choosing where to deploy medical staff is an important consideration. An analysis of the data suggests that resuscitation facilities should be concentrated towards the end of the race, although clearly cover needs to be available along the entire course.
There are a number of limitations to this study. First, as already mentioned, the methodology of many of the studies may not have captured all deaths, particularly those studies where the investigators were not intimately involved with the marathon and relied on surveys and scanning newspaper and other sources of information. Therefore, the true death rate from marathon running may be higher. A limitation of all studies was that participants may have run multiple marathons, and therefore the total number of unique participants would likely have been lower, raising the individual risk further.
Second, in many situations the cause of death was not available, and therefore causes such as heatstroke may be of greater concern than realised. Finally, there were no data on the medical history of patients, or any symptoms experienced prior to participation. Such information may reveal symptoms or signs that could help reduce the risk of death further.
In conclusion, running marathons is generally safe for the overwhelming majority of participants, but fatalities will occur, principally towards the end of an event. Comprehensive testing of athletes would be required to significantly reduce the number of events, and this may not be cost-effective, or desirable. Other measures, such as the correct stationing of resuscitation facilities, prophylactic aspirin for older male competitors, showers and suitably hydration advice may be more effective, but this remains to be proven.