Evaluation of cyclooxygenase 2 inhibitor use in patients admitted to a large teaching hospital

The heavy usage of coxibs in Australia far outstrips the predicted usage that was based on the treatment of patients with risk factors for upper gastro-intestinal adverse events from conventional anti-inflammatory agents. This raises questions regarding the appropriateness of prescribing.

To determine: (i) the relationship between prescriptions for cyclooxygenase 2 (COX-2) inhibitors and objective evidence of inflammatory arthritis, (ii) prior experience with paracetamol and/or conventional non-steroidal anti-inflammatory drugs (NSAIDs), and (iii) contraindications to the use of NSAIDs.

Drug utilization evaluation and rheumatological assessment was conducted on 70 consecutive patients admitted on COX-2 inhibitors to a 480-bed metropolitan hospital. The main outcome measures were: the indication for COX-2 inhibitor; objective evidence of inflammatory arthritis; previous trial of paracetamol or conventional NSAIDs; and patient satisfaction.

Only 11 patients (16%) had symptoms or signs of an inflammatory arthropathy, and met Pharmaceutical Benefits Schedule criteria for prescribing a COX-2 inhibitor. Fifty-nine patients (84%) had chronic osteoarthritis, degenerative spinal disease, injury or malignancy, without overt active inflammation. Fourteen patients (20%) had trialled regular paracetamol prior to using any NSAID treatment. Conventional NSAIDs had been previously used by 51 patients (73%). Eleven patients (16%) reported previous adverse gastrointestinal effects from conventional NSAIDs. On the basis of significant renal impairment (creatinine clearance <50 mL/min) or cardiac failure, cautions or contraindications applied to the use of any form of NSAID in 49% of patients. Fifteen patients (21%) had demonstrable worsening of their renal function after commencement of a COX-2 inhibitor. Thirty-one percent of patients considered the drug was effective (rated >5/10).

Drug utilization data indicate that COX-2 inhibitors are frequently used first line for degenerative osteoarthritis in the absence of overt inflammation, without prior adequate trial of paracetamol and with disregard for the cautions and contraindications of these agents. These findings may explain the unprecedented Pharmaceutical Benefits Schedule expenditure on COX-2 inhibitors in Australia.