In this contemporary national representative NSAID nested-control cohort study, we found that the use of nonselective NSAIDs rather than COX-2-selective NSAIDs was associated with increased risk of hospitalization for AKI within 1 month of 1st prescription, although the risk was not increased in past users than unexposed controls, possibly due to confounding in baseline covariates between remote exposure and outcomes or representing a selected population less vulnerable to nephrotoxicity so that no more AKI events could be detected. The gene discussed is PTGS2; the disease is acute kidney injury.