Animal model of acute gout reproduces the inflammatory and ultrasonographic joint changes of human gout.

INTRODUCTION: Gout is an inflammatory condition induced by the deposition of monosodium urate (MSU) crystals in the joints and soft tissues that can produce acute or chronic arthritis. Several animal models of crystal-induced inflammation have been proposed that involve direct injection of MSU-crystals into different anatomical structures; however, only a few of these models reflect a true diarthrodial joint microenvironment in which an acute gouty attack takes place. The aim of this study was to assess the inflammatory and structural joint changes in a rabbit model of acute gout attack by ultrasound (US), synovial fluid (SF) and histopathological analyses. METHODS: Under US guidance, 42 rabbit knees were randomly injected with a suspension of 50 mg/ml of either MSU or allopurinol synthetic crystals. The control group received intra-articular vehicle of phosphate-buffered saline (PBS). US evaluation, SF and histopathological analyses were performed at days 1, 3, and 7. RESULTS: A total of 21 rabbit knees were assigned to the control group, 12 to the MSU-crystals group, and 9 to the allopurinol crystals group. By US, the MSU crystals group displayed the double contour sign and bright stippled aggregates in 67% and 75% of joints, respectively. Neither control knees nor allopurinol crystals group displayed these US signs. Power Doppler (PD) signal was moderate to intense in the MSU-crystals group and greater than both the allopurinol crystal and control groups at day 1 (P<0.001) and 3 (P<0.05), with its practical disappearance by day 7. SF leukocyte count was 40,312±6,369 cells/mm3 in the MSU-crystals group, higher than in controls (P=0.004) and allopurinol crystal group (P=0.006). At day 7, SF leukocyte count decreased in both MSU and allopurinol crystal groups reaching the non-inflammatory range. Histologically, at day 3 intense synovial polymorphonuclear cells infiltration and MSU aggregates were identified. CONCLUSION: The rabbit model of MSU crystal-induced acute arthritis efficiently reproduces the inflammatory, US, SF and histopathological changes of the human acute gouty attack.

Diagnosis of chronic gout: evaluating the american college of rheumatology proposal, European league against rheumatism recommendations, and clinical judgment.

OBJECTIVE: Observation of monosodium urate (MSU) crystal is the gold standard for diagnosis of gout, but is rarely performed in daily clinical practice, and diagnosis is based on clinical judgment. Our aim was to identify clinical and paraclinical data included in the European League Against Rheumatism recommendations (EULARr) and American College of Rheumatology proposed criteria (ACRp) for diagnosis of gout in patients with chronic gout according to their attending rheumatologists. METHODS: This cross-sectional and multicenter study included consecutive patients from outpatient clinics with a diagnosis of gout by their attending rheumatologists according to their expertise. The frequency of each item from the ACRp and EULARr was determined. Possible combinations of the items that were frequent, clinically relevant, and simple to evaluate in daily practice were determined. RESULTS: We studied 549 patients (96% men), mean age 50 +/- 14 years. Analysis of MSU crystals was performed in 15%. We selected 7 clinical criteria and 1 laboratory measure because of their frequency, importance, and simplicity to obtain: current or past history of: > 1 attack of acute arthritis (93%); mono or oligoarthritis attacks (74%); rapid progression of pain and swelling (< 24 hours; 74%); podagra (70%); erythema (56%); unilateral tarsitis (33%); tophi (52%); and hyperuricemia (93%). The chronic gout diagnosis (CGD) proposal comprised >or= 4/8 of these; 88% of patients had the criteria of the CGD proposal while 75% had 6/11 ACRp criteria (p = 0.001). When analysis of MSU crystals was added, 90.1% (CGD) and 83.9% (ACRp) met the criteria (p = 0.004). CONCLUSION: Current or past history of >or= 4/8 CGD parameters is highly suggestive of chronic gout.

Validation of the Health Assessment Questionnaire disability index in patients with gout.

OBJECTIVE: To assess the psychometric properties of the Health Assessment Questionnaire (HAQ) disability index (DI) in patients with gout. METHODS: This study was conducted in a multicenter cohort of patients with gout whose data were collected at baseline (time 0) and 6 months later (time 6). Reliability was assessed by test-retest reliability (intraclass correlation coefficient [ICC]) and internal consistency (Cronbach's alpha coefficient). Construct validity was assessed with convergent validity (HAQ DI correlation with Short Form 36 [SF-36]) and discriminative validity (HAQ DI correlation with clinical features). Sensitivity to change was determined by comparing HAQ DI time 0 versus HAQ DI time 6 (percentage of change, effect size, smallest real difference [SRD], and Guyatt's responsiveness index [GRI]). RESULTS: We included 206 patients (96.6% men, mean +/- SD age and disease duration 56.3 +/- 12.4 years and 9.3 +/- 8.5 years, respectively). Of these, 52.4% had joint pain, 22.8% swelling, 32.5% reduced joint mobility, and 36.9% tophi. The mean HAQ DI score was 0.59 +/- 0.77 (95% confidence interval [95% CI] 0.49-0.70). ICC (n = 36, evaluations at baseline and 5 days later) was 0.76. Cronbach's alphas were 0.91 (95% CI 0.88-0.92, P = 0.000) for the 20 HAQ DI items and 0.93 (95% CI 0.92-0.94, P = 0.000) for the 8 HAQ DI categories. The HAQ DI correlated in predictable ways with SF-36 subscales and clinical variables, and discriminated between subgroups with and without any joint pain, swelling, and tophi. Concerning sensitivity to change (n = 167), the difference between HAQ DI time 0 and HAQ DI time 6 was 0.31 +/- 0.58 (effect size 0.62, SRD 0.59, and GRI 1.91). DeltaHAQ DI correlated with Deltapain (r = 0.349, P = 0.000). CONCLUSION: The HAQ DI is a valid and reliable measure of functioning in patients with gout.