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Chronic gout, renal function, and NSAIDs

 

Clinical bottom line

Reducing serum urate levels to withdraw chronic NSAID use can improve renal function in gout. Predictors for impaired renal function were age, prior renal problems, hypertriglyceridaemia and hypertension.


Reference


F Perez-Ruiz et al. Improvement of renal function in patients with chronic gout after proper control of hyperuricemia and gouty bouts. Nephron 2000 86: 287-291.


Method

This was a prospective observational study of patients with chronic gout who regularly used NSAIDs fro the control of gouty bouts in a hospital gout clinic. Baseline evaluations were made after two weeks on a normal diet in which NSAIDs had been withdrawn. Various clinical, demographic and blood sample information was recorded.

The intervention in all patients was institution of adequate treatment with allopurinol or benzobromarone (or both) to achieve a serum urate level of less than 0.28 mmol/L (6 mg/100 mL, their conversion). Patients were followed up every 3-6 months for one year. Normal renal function was defined as a 24-hour creatinine clearance of more than 80 mL/min/1.73 sq metres of body surface area. Improvement in renal function was defined as at least 20% increase in creatinine clearance, and worsening as a t least 20% decrease from baseline.

Results

Eighty-seven patients (2 women) who completed the 12 month NSAID withdrawal were available for analysis. Allopurinol (100-600 mg/day) was used in 38, benzbromarone (50-150 mg/day) in 39 and a combination in 10. This reduced serum urate levels from an initial mean of 0.43 mmol/L to 0.22 mmol/L.

Renal function was impaired (creatinine clearance less than 80 mL/min/1.73 sq metres) in 29/87 patients initially but only 19/87 at one year. Improved renal function occurred in 30/87 patients, and worsening in 4/87. After urate lowering and a year free from gouty attacks the mean creatinine clearance rose from 94 to 104 mL/min/1.73 sq metres.

Using a regression analysis, age, prior renal problems, hyptertriglyceridaemia and hypertension were independently associated with a lower initial creatinine clearance.

Comment

Not a randomised trial, this, and it may have some defects. For instance, it tell us the number of patients for whom results were available, but not how many from whom results were not available because they did not complete 12 months. It's worth a read, though, because long-term use of NSAIDs is associated with renal problems, as any renal unit will tell you, and as other stories in Bandolier explore. What is irritating is that the implication is that these 87 patients had no gouty attacks in this year of treatment compared with an average of three a year beforehand. This study may be telling us important things about successful treatment of gout.