By contrast, a Canadian-based registry study demonstrated that elevated risk of AKI was evident among COX-2 inhibitor users (including rofecoxib and celecoxib) although the risk seemed to be insignificant for low-dose users.12 However, their results originated from older patients (mean age,78 years) than those in the present study (mean age, 67 years). This evidence concerns the gene PTGS2 and acute kidney injury.