The first metatarsophalangeal joint in gout: a systematic review and meta-analysis

Background: The aim of this review was to qualitatively synthesise studies that have investigated characteristics of the first metatarsophalangeal joint (1st MTP) in gout and to undertake a meta-analysis to estimate the average prevalence of acute 1st MTP arthritis across studies in people with gout. Methods: Studies published in English were included if they involved participants who had a diagnosis of gout and presented original findings relating to the following outcome measures associated with the 1st MTP: epidemiology; clinical features; structural and functional characteristics; and microscopic and imaging features. Results: Forty-five studies were included in the qualitative synthesis. 1st MTP pain was a prominent feature in people with gout. People with 1st MTP gout reported walking-and general-disability. Structural and functional characteristics of 1st MTP gout included hallux valgus, osteoarthritis, and restricted joint motion. Successful crystal aspiration ranged from 81 to 91 % and positive crystal identification via microscopy ranged from 83 to 93 % in patients with a history of 1st MTP gout. Imaging features were common at the 1st MTP including the double contour sign, tophi and erosions. Eleven studies involving 2,325 participants were included in the meta-analysis, providing an estimate of the average prevalence of acute 1st MTP arthritis across studies of 73 % (95 % prediction interval 40-92 %; range 48-97 %; I-2 = 93 %). Conclusions: 1st MTP acute arthritis is highly prevalent in people with gout and has a substantial impact on patient-reported pain and disability. Gout affects the structure and function of the 1st MTP. Microscopic and imaging studies have demonstrated crystal deposition and joint damage at the 1st MTP in people with gout.