Delzer LM, et al. - Experts evaluated sequential measures of kidney function in hospitalized adult solid organ or allogeneic hematopoietic stem cell transplant recipients who received maintenance calcineurin inhibitor (CNI) therapy and concurrent treatment with an oral or parenteral nonsteroidal anti-inflammatory drug (NSAID) to clarify the uncertainties regarding drug interaction between CNIs and NSAIDs and the level of risk for adverse renal effects related to this interaction. An increase in serum creatinine above baseline was seen in 80.5% of hospitalized patients on CNI therapy who were exposed to NSAIDs vs 56.3% of patients on CNIs who were not. NSAID administration independently predicted a rapid increase in serum creatinine. Among patients exposed to parenteral ketorolac, the event rate for worsened renal function was highest. Concurrent use of these medications is not recommended due to the likelihood of developing treatment-related worsening of renal function is higher when using CNIs and NSAIDs in combination. Patients and clinicians should be advised of these results.