Influence of creatinine versus glomerular filtration rate on non-steroidal anti-inflammatory drug prescriptions in chronic kidney disease

Background: Non-steroidal anti-inflammatory drugs (NSAIDs), including cyclooxygenase-2 (COX-2) inhibitors, are generally contraindicated in chronic kidney disease (CKD). This investigation sought to identify the frequency of NSAID/COX-2 prescription and to determine the influence of serum creatinine (Cr) versus estimated glomerular filtration rate (eGFR) on this practice pattern. Methods: An established Veterans Health Administration CKD safety cohort (n = 70,154) was examined to determine the frequency of NSAID/COX-2 in fiscal year 2005 (FY05) for up to 30 days preceding the index hospitalization and as many as 365 days during that year. Binomial regression was used to determine adjusted prevalence ratios for prescription of NSAID/COX-2 with respect to continuous eGFR measurement and serum Cr categories. CKD was defined as eGFR <60 ml/min/1.73 m². Results: 15.4% of the subjects had an NSAID/COX-2 prescription during the observation period. The proportion of these prescribed agents decreased with declining renal function, but remained significant at any stage of CKD given the renal harm related to these medications. At specific GFR estimates, serum Cr remained a significant predictor of NSAID/COX-2 prescription. At GFR set at 42 ml/min/1.73 m², the predicted proportion of prescribed NSAID/COX-2 was 0.29 (95% CI 0.24, 0.36), 0.23 (95% CI 0.22, 0.26), 0.20 (95% CI 0.19, 0.22), and 0.12 (95% CI 0.10, 0.14) for Cr strata of ≤1.3, 1.4-1.6, 1.7-2.1, and ≥2.2 mg/dl, respectively (all p < 0.05). Conclusion: A significant proportion of individuals with CKD continue to be prescribed NSAID/COX-2 and serum Cr remains an influential guide to NSAID/COX-2 prescription, even in GFR ranges where these agents are ill advised.