Don't Be Fooled by Normal Serum Urate in Acute Gout

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Don't Be Fooled by Normal Serum Urate in Acute Gout
Rheumatology News Volume 7, Issue 8, Page 22 (August 2008) (http://www.rheumatologynews.com/article/PIIS154198000870468X/abstract)
Serum urate levels are often normal during acute gouty arthritis attacks, according to Dr. Naomi Schlesinger. In the study of 339 patients with acute gouty arthritis whose serum urate levels were measured, 29% of individuals on chronicallopurinol had a true-normal serum urate level, defined as 6 mg/dL or less. Among patients not on the hypouricemic agent, 11% had a true-normal serum urate level during their acute episode of gout.

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Serum Urate During Acute Gout.
Schlesinger N, Norquist JM, Watson DJ.
J Rheumatol. 2009 Apr 15. [Epub ahead of print] (http://www.ncbi.nlm.nih.gov/pubmed/19369457?dopt=Abstract)
OBJECTIVE: To study the frequency of normal serum urate (SU) levels during acute gout in the largest studies of acute gout treatment to date.

METHODS: Data collected from 2 randomized controlled clinical trials assessing the efficacy of etoricoxib or indomethacin for 7 days in acute gout were used to assess SU levels during acute gouty attacks. Efficacy was similar with both agents, so both groups were combined for analysis.

RESULTS: A total of 339 patients were enrolled in the 2 studies; 94% were male; mean age was 50.5 years. At baseline, 14% of patients had a "true" normal SU (</= 6 mg/dl) and 32% had SU </= 8 mg/dl during acute gout. Baseline mean SU was 7.1 versus 8.5 mg/dl (p < 0.001) in those taking allopurinol versus nonusers. Patients taking chronic allopurinol were more likely to have lower SU at baseline compared to those not taking chronic allopurinol (p < 0.001) during the acute attack.

CONCLUSION: A normal SU level at presentation does not exclude an acute gouty attack. In the largest studies of acute gout to date, attacks still occurred despite SU levels being below 6.8 mg/dl, the saturation level for urate. This may be attributed to persistence of tophi and an increased body uric acid pool. Additional studies are needed to determine the correlation between SU and the body uric acid pool as well as the relationship to timing of changes during acute gout.

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Frequency, Risk, and Cost of Gout-related Episodes Among the Elderly: Does Serum Uric Acid Level Matter?
Wu EQ, Patel PA, Mody RR, Yu AP, Cahill KE, Tang J, Krishnan E.
J Rheumatol. 2009 Apr 15. [Epub ahead of print] (http://www.ncbi.nlm.nih.gov/pubmed/19369467?dopt=Abstract)
OBJECTIVE: We examined the association between serum uric acid (SUA) level and the frequency, risk, and cost of gout flares among the elderly.

METHODS: Data were extracted from the Integrated Healthcare Information Services claims database (1999-2005). Patients were included if they had gout, were aged 65 years and older and had both medical and pharmacy benefits, and electronic laboratory data. Patients with gout and gouty episodes were identified using algorithms based on ICD-9-CM codes and medications. Logistic regression and negative binomial regressions were used to study the relationship between SUA concentration and the annual frequency and one-year risk of gout episodes. Generalized linear models were used to examine the direct healthcare costs associated with gout episodes in the 30 days following each episode.

RESULTS: Elderly patients with gout (n = 2237) with high (6-8.99 mg/dl) and very high (> 9 mg/dl) SUA concentrations were more likely to develop a flare within 12 months compared to patients with normal (< 6 mg/dl) SUA levels (OR 2.1, 95% CI 1.7-2.6; OR 3.4, 95% CI 2.6-4.4, respectively). In multivariate regressions, the average annual number of flares increased by 11.9% (p < 0.001) with each unit-increase in SUA level above 6 mg/dl (p < 0.001). Among patients with very high SUA levels, average adjusted total healthcare and gout-related costs per episode were $2,555 and $356 higher, respectively, than those of patients with normal SUA levels (both p < 0.001).

CONCLUSION: Higher SUA levels are associated with increased frequency and risk of gout episode, and with higher total and gout-related direct healthcare costs per episode.