Usefulness of plain radiography for assessing hypouricemic treatment response in patients with tophaceous gout

Abstract

Aim: To investigate whether plain radiography is useful for assessing the changes in gouty tophi size following hypouricemic therapy.

Methods: Gout was diagnosed according to the American College of Rheumatology criteria. Before and after hypouricemic treatment, serum uric acid level was measured, and plain radiography was performed to measure gouty tophi size. The tophi were graded by measuring the maximum vertical and horizontal diameters, and they were scored by adding up the scores of the grades. The vertical diameter was measured on both sides of the proximal phalanges (PPs). The horizontal diameter was measured on the lateral side of the PPs. The maximum vertical diameter measurement was graded 0-4. The maximum horizontal diameter measurement was graded 0-3.

Results: Seven hundred first metatarsal phalangeal joints (MTPJ) of 350 patients with gout were assessed for gouty tophi. Tophi were observed using plain radiography in 174 MTPJs (24.9%) of 109 patients (31.1%). Follow-up plain radiography was performed in 60 of these patients. Before the treatment, the average serum uric acid level of these patients was 8.3 ± 1.9 mg/dL, and the average tophi score was 3.7 ± 2.5. After hypouricemic treatment, the uric acid level decreased to 5.9 ± 1.6 mg/dL (P < 0.05), and the average tophi score decreased to 1.5 ± 1.8 (P < 0.05).

Conclusions: This new method for measuring gouty tophi using plain radiography may be useful for evaluating changes in gouty tophi size following hypouricemic treatment.

Keywords: X-rays; arthritis; gout; urate-lowering therapy; uric acid.