Increased Spinal Monosodium Urate Deposition Among Individuals With Gout

Individuals with gout were found to exhibit greater lumbosacral spine (LS) monosodium urate (MSU) deposition and intercritical inflammation, according to research results presented at the American College of Rheumatology (ACR) Convergence 2021, held virtually from November 3 to 10, 2021.

The investigators recruited 75 individuals with gout, 72 of whom completed the study. Age was similar among the control (61.8±3.8 years), nontophaceous (64.0±6.1 years), and tophaceous (60.4±11.0 years) groups (P =.81), ranging from 45 to 80 years. Exclusion criteria included spondyloarthropathy, rheumatoid arthritis, active spinal malignancy, urate-lowering treatment (ULT) of 6 months or more, and calcium pyrophosphate dihydrate crystal deposition disease. The ACR gout classification criteria of serum urate level greater than 6.8 mg/dL or greater than 6.0 if patients received ULT for less than 6 months were applied at study entry. The researchers collected demographic information, Aberdeen back pain scale, gout history, serum urate level, C-reactive protein level, and erythrocyte sedimentation rate (ESR). To assess MSU deposition, dual-energy CT (DECT) of the lumbosacral spine was performed.

Body mass index differed significantly between the control (28.3±6.5), nontophaceous (34.1±7.2), and tophaceous (29.5±4.5) groups (P =.03), as did creatinine level (1.0±0.2 mg/dL, 1.4±0.7 mg/dL, and 1.4±0.6 mg/dL, respectively; P <.05). Individuals with gout exhibited higher mean serum urate levels (control, 5.3±1 mg/dL, nontophaceous, 8.5±1.7 mg/dL, and tophaceous, 8.5±1.6 mg/dL; P <.05) and ESR (control, 13.7±13.8 mm/h, nontophaceous, 26.5±19.4 mm/h, and tophaceous, 25.1±15.7 mm/h; P <.05). MSU volumes were larger among those with gout compared with the control group (5.23±6.9 cm³ vs 2.2±1.2 cm³, respectively; P =.03) and greater among the tophaceous vs the nontophaceous group (6.0±8.9 cm³ vs 4.4±4.3 cm³). Use of highly specific DECT settings to eliminate artifact confirmed greater deposition among those with gout despite decreasing the number of individuals with MSU (n=29; control, 0/9; tophaceous with deposition, 2/9; nontophaceous with deposition 1/11). Back pain was reported more frequently by patients with gout.  Spinal DECT did not demonstrate frank tophi in any patient.

The study authors concluded, “[Patients with] gout have significantly greater intercritical inflammation and [lumbosacral spine] MSU deposition than control [participants]” and report a “trend toward greater deposition among patients with tophi.”

Disclosure: This clinical trial was supported by Horizon Therapeutics plc. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Toprover M, Mechlin M, Slobodnick A, et al. Assessing the extent of lumbosacral spinal urate deposition in patients with tophaceous and nontophaceous gout compared with non-gout controls using dual-energy CT (DECT). Poster presented at: ACR Convergence 2021; November 3-10, 2021. Abstract 467.