Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Calcium Pyrophosphate Crystal Arthritis (CPPA) Is a Frequent Cause of Refractory Gout.

Perez-Ruiz1,  Fernando, Herrero-Beites3,  Ana M., Alonso-Ruiz2,  Alberto, Calabozo2,  Marcelo

Hospital de Cruces, Jopelana, Spain
Hospital de Cruces
Hospital de Górliz

Background:

Proper treatment of hyperuricemia of gout is associated with a reduction in the number of flares to less than 10% of patients after 12-month therapy suffer from gout flares (Schumacher HR, Rheumatology 2009, Becker MA, J Rheumatol 2009).

Objective:

to evaluate the impact of coexistent CPPA in joint flares in patients with gout.

Methods:

analysis of data from a cohort of 610 patients with a diagnosis of gout based on monosodium urate (MSU) crystal observation and who showed proper control (serum urate <6 mg/dl) of uric acid at 12-month follow-up, and colchicine prophylaxis stopped. CPPA was defined as presence of CPP crystals in the cytoplasm of white cells in synovial fluid (SF) samples and radiographic chondrocalcinosis. Microscopy procedures for observation and identification of MS and CPP crystals included normal light and polarized light with first order red compensator 400x. Contrast-phase 400x and 1000x microscopy was used was used in addition to further investigate SF samples negative for crystals with normal and polarized microscopy.

Results:

23/610 (3.8%) patients with crystal-proven gout also had a diagnosis of CPPA. Of them, 6 showed both MSU and CPP crystals in the same synovial fluid sample, prior or during the first year of urate-lowering treatment, so they were maintained on colchicine prophylaxis and not included in further analysis. The remaining 17 patients showed CPP crystals during further follow-up, CPPA appearing at mean follow-up of 40±16 months (range 18 to 94). Overall, 49/610 (8.03%) patients had at least an episode of acute arthritis that was attributed to "refractory" gout, 17/49 (34.7%) showing CPP crystals in the cytoplasm of leukocytes and Xray chondrocalcinosis. There was no difference in any feature in patients with gout vs. patients with gout+CPPA, except for mean age (59±12 vs. 71±12 years), BMI (28.1±3.6 vs.26.5±3.3 kg/m2), and clearance of creatinine (87±33 vs. 62±30 ml/min).

Conclusions:

definite CPPA in patients with crystal proven gout is found in up to 4% of patients with gout. CPP arthritis comprised for one third of the flares that appeared after 1-yr control of hyperuricemia. Synovial fluid samples should be obtained and carefully studied before considering "refractory gout" diagnosis.

To cite this abstract, please use the following information:
Perez-Ruiz, Fernando, Herrero-Beites, Ana M., Alonso-Ruiz, Alberto, Calabozo, Marcelo; Calcium Pyrophosphate Crystal Arthritis (CPPA) Is a Frequent Cause of Refractory Gout. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :873
DOI: 10.1002/art.28641

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