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071 Slower runners, older females and route characteristics are independent risk factors for serious/life-threatening medical encounters in a 90 km ultramarathon: a SAFER study in 70328 runners over 5 years
  1. Nicola Sewry1,2,
  2. Jeremy Boulter3,
  3. Martin Schwellnus1,2
  1. 1Sport, Exercise Medicine and Lifestyle Institute (SEMLI), Pretoria, South Africa
  2. 2IOC Research Centre, South Africa, Pretoria, South Africa
  3. 3Medical Director, Comrades Marathon, Pietermaritzburg, South Africa


Background Serious/life-threatening medical encounters (sltMEs) occur during mass community-based events, with higher incidences in ultra-endurance events. Risk factors associated with sltMEs are under-investigated.

Objective To determine independent risk factors for serious/life-threatening MEs in a 90 km ultramarathon running event.

Design Retrospective clinical audit, cross-sectional analysis

Setting 2014–2018 Comrades ultramarathon (90km, alternating annually between an ‘up’ vs. a ‘down’ run between a coastal and inland city), South Africa

Participants 70328 race starters

Interventions All entrants voluntarily completed two medically-related questions: 1) history of allergies, and 2) history of any medical condition and/or medication use. Race day data (start time, finish time, age, sex, ‘up’ vs. ‘down’ run) was recorded by the race organisers; and sltMEs (as defined in the 2019 consensus statement on mass community-based events) were recorded by race medical staff during and immediately after the event.

Main Outcome Measures Independent risk factors associated with sltMEs (injury- and illness-related) using demographics (age, sex), race day factors (route ‘up’ or ‘down’; race pace), and individual self-reported medical history (allergies, medical conditions/medication use) were investigated using a multivariate model with a Poisson distribution, reporting the prevalence ratio (PR: 95% CI).

Results 159 serious/life-threatening medical encounters were recorded over the 5 years. The following independent risk factors were associated with serious/life-threatening medical encounters: age and sex (males 31–40 yrs vs females >50 yrs, 0.3: 0.1–0.7, p=0.0076; males 41–50 yrs vs females >50 yrs, 0.2: 0.1–0.4, p=0.0002; males >50 yrs vs females >50 yrs, 0.4: 0.2–0.9, p=0.0323), running pace (6-<7 min/km vs 8-<9 min/km, 0.4: 0.2–0.8, p=0.0062; 7-<8 min/km vs 8-<9 min/km, 0.5: 0.3–0.9, p=0.0299) and route (up vs. down, 0.5: 0.3–0.8, p=0.0046).

Conclusion Older females, slower runners and route (down run) were independent factors associated with higher risk of serious/life-threatening MEs in a 90 km ultramarathon. These data will form the basis to design and implement prevention programs to manage risk of sltMEs at these events.

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