Yes its over 20 years old, the first link was about renal issues in those who did not have preexisting conditions with their kidneys.
"Ibuprofen-associated, acute, reversible renal failure with hyperkalemia, tubular necrosis, and proteinuria developed in a patient who had no predisposing underlying disease."
Working at a large HMO provider back home I had the opportunity to speak directly with Dr's, Nurses, Specialist, etc. The general consensus in the medical community was that Ibuprofen and its derivatives cause renal problems and if they had a choice, they would prescribe codiene in lieu of IBP. But due to people not being able to control themselves, and people getting high or low in this case, they dont dispense unless the pain is severe or if the patiently specificially asks for it.
The chemical cousin of Codiene - Vicodin/hydrocodone invented because people were getting addicted to Codiene is not as effective as Codiene. It is not as fast acting and the half life of the drug is shorter than Codiene.
It's is not scare mongering at all, the kidneys much like the liver is designed to work very efficiently. One can lose 90% of the organs functions and still feel fine, its not until you pass the 90% thereshold will you notice that things are amiss.
Furthermore, how many people actually get their blood work done to check on hematocrit, bilirubin, on a regular basis?
Lastly, it was more than 30+ years ago Dioxin was deemed carcinogenic and mutagenic. Now 30+ years later I would not want to sprinkle it on my food.
I would take my chances, error on the side of caution and take codiene in lieu of IBP. Especially since its OTC here in HK and you dont need a script for it.