52% of runners on ibuprofen showed kidney injury, and 34% on placebo
In an 80 km desert ultramarathon among 89 runners, the gap was not statistically significant, and injury here means a creatinine rise measured at the finish.
What the study found
Half the runners on ibuprofen finished with kidney injury
In an 80 km desert ultramarathon, 52% of runners randomised to ibuprofen showed acute kidney injury at the finish against 34% on placebo, about one extra case for every 5.5 runners taking it. A third of the placebo group had it too, so the race supplied most of the harm.
The caveat · The 18-point gap missed significance
Eighty-nine runners, and the 18-point gap was not statistically significant, with an interval running from 4 points the other way to 41 points in favour. Kidney injury here means a creatinine rise measured at the finish line, a marker that often settles, not a clinical kidney outcome with follow-up. Runners who lost more weight during the race were independently more likely to be affected, so dehydration and the drug are tangled together in these numbers. Multi-day desert racing in heat is a deliberately stressed setting.
What we don't know
Eighty-nine runners, and the 18-point gap was not statistically significant, with an interval running from 4 points the other way to 41 points in favour. Kidney injury here means a creatinine rise measured at the finish line, a marker that often settles, not a clinical kidney outcome with follow-up. Runners who lost more weight during the race were independently more likely to be affected, so dehydration and the drug are tangled together in these numbers. Multi-day desert racing in heat is a deliberately stressed setting.