The burden of subclinical intra-articular inflammation in gout

Objective To assess the burden of subclinical intra-articular inflammation using ultrasound in people with gout. Methods A pilot, prospective longitudinal cohort of 28 participants with gout were examined twice, once during a gout flare (n = 25) and then during an inter-critical phase (n = 27). At each visit, a 52 joint count was done followed by ultrasound examination for detection of intra-articular power Doppler (PD) signal. Clinically active joints were defined as tender and swollen. Data was collected on patient reported gout pain - visual analog scale (VAS) (painVAS), physician global VAS (physicianVAS), Health Assessment Questionnaire (HAQ), serum uric acid, erythrocyte sedimentation rate (ESR), and high-sensitivity C-reactive protein (HsCRP). Results At the flare visit, participants had a median of 1 clinically active joint (interquartile range [IQR] 1-2), and a median of 5 joints with a PD score >= 2 (IQR 4-10, P < .001). At the inter-critical visit, participants reported an median of 0 clinically active joints (IQR 0-0), and a median of 4 joints with a PD score >= 2 (IQR 3-7, P < .001). Physician VAS (5.69 vs 3.40, P < .001), painVAS (6 vs 0, P < .001), HAQ (0.75 vs 0.12, P = .032), and ESR (29 vs 13.5 mm/h, P = .02) were higher at the acute visit, but HsCRP levels were similar (8.88 vs 5.15 mg/L, P = .062). Conclusion This pilot study established the presence of subclinical intra-articular inflammation in gout at both acute and inter-critical phases. Despite the apparent resolution of symptoms after an acute flare, a relatively high proportion of joints had subclinical inflammation in the inter-critical visit. The long-term implications of untreated subclinical joint inflammation are not clear.