Acute kidney injury (AKI) may be more frequent in ultramarathon runners who take ibuprofen, according to a randomized controlled trial in Emergency Medicine Journal.
The study included 91 athletes participating in 50-mile ultramarathon races in desert environments. Runners were randomly assigned to take ibuprofen 400 mg or placebo tablets every 4 hours during their race. Incidence of AKI was compared between groups: “risk” was defined as a 1.5-fold increase in creatinine and “injury” as a twofold increase. Runner characteristics were similar between groups; in the ibuprofen group, average total dose was 1200 mg.
Overall AKI incidence was 44%. On intention-to-treat analysis, AKI occurred in 52% of runners taking ibuprofen versus 34% taking placebo. The 18% difference exceeded the 15% noninferiority threshold. However, the number needed to harm was 5.5 ibuprofen-treated runners to cause 1 additional case of AKI.
Both categories of AKI were more frequent with ibuprofen: 38% versus 26% for “injury” (nonsignificant) and 14% versus 9% for “risk” (significant). Slower finishers were less likely to develop AKI: odds ratio (OR) 0.67. Greater weight loss was associated with a higher risk of AKI: OR 1.2 at a 1.3% reduction in body weight.
Studies have reported 34% to 85% rates of AKI in ultramarathoners. Although it has been suggested that nonsteroidal anti-inflammatory drugs (NSAIDs) might contribute to these events, up to three-fourths of runners still take NSAIDs during races. The evidence for and causal nature of this association are unclear.
Despite the lack of statistical significance, this trial suggests an increased risk of AKI in ultramarathon runners who use ibuprofen. Taking NSAIDs during endurance running “could exacerbate renal injury,” the researchers write. They note that associations of AKI with finishing time and weight loss suggest a role of dehydration [Lipman GS, et al. Ibuprofen versus placebo effect on acute kidney injury in ultramarathons: a randomised controlled trial. Emerg Med 2017; doi: 10.1136/emermed-2016-206353].