Incidence and Prevalence of Acute Kidney Injury During Multistage Ultramarathons

Determine prevalence, incidence, and risk factors of acute kidney injury (AKI) during multistage ultramarathons.

Prospective observational cohort study.

Jordanian Desert 2012; Atacama Desert, Chile 2012 and 2013; and Gobi Desert 2013 RacingThePlanet 250 km, 6-stage, ultramarathons.

One hundred twenty-eight participants (384 measurements) from the Jordan (25, 19.5%), Gobi (35, 27.3%), 2012 Atacama (24, 18.8%), and 2013 Atacama (44, 34.4%) races.

Blood samples and weights were gathered and analyzed immediately after stage 1 (40 km), 3 (120 km), and 5 (225 km).

Changes in serum creatinine (Cr), cumulative incidence, and prevalence of AKI were calculated for each stage with "risk of injury" defined as 1.5 × baseline Cr and "injury" defined as 2 × Cr.

Cumulative incidence of AKI was 41.4%. Stage 1 had 56 (43.8%) with risk of AKI and 24 (18.8%) with injury; in stage 3, 61 (47.7%) were at risk, 41 (32%) had injury; in stage 5, 62 (48.4%) runners were at risk and 36 (28.1%) had injury. Acute kidney injury was significantly associated with females [odds ratio (OR), 4.64; 95% confidence interval (CI), 2.07-10.37; P < 0.001], lower pack weight (OR, 0.71; 95% CI, 0.56-0.91; P < 0.007), and percentage weight loss (OR, 0.87; 95% CI, 0.78-0.97; P < 0.015). Lowest quintile of finishers was less likely to develop AKI (OR, 0.18; 95% CI, 0.04-0.78; P < 0.022).

Prevalence of AKI was 63%-78% during multistage ultramarathons. Female sex, lower pack weight, and greater weight loss were associated with renal impairment.