Comparison Between Early-Onset and Common Gout: A Systematic Literature Review

Gout is an inflammatory, metabolic disease associated with a high comorbidity burden including cardiovascular disease, hypertension, type 2 diabetes, hyperlipidemia, renal disease, and metabolic syndrome. Approximately 9.2 million Americans have gout, making prognosis and treatment outcome predictors highly important. About 600,000 Americans have early-onset gout (EOG), generally defined as first gout attack at ≤ 40 years of age. However, data on EOG clinical features, comorbidity profile, and treatment response are sparse; this systematic literature review provides insight. PubMed and American College of Rheumatology (ACR)/European Alliance of the Associations for Rheumatology (EULAR) abstract archives were searched for early-onset gout, "early onset gout," and ("gout" AND "age of onset"). Duplicate, foreign language, single case report, older (before 2016), and irrelevant/data insufficient publications were excluded. The age of diagnosis categorized patients as having common gout (CG, generally > 40 years) or EOG (generally ≤ 40 years). Applicable publications were extensively reviewed/discussed among authors for inclusion/exclusion consensus. A total of 283 publications were identified, with 46 (35 articles, 10 abstracts) reviewed and 17 (12 articles, 5 abstracts) ultimately included. Eleven reported clinical characteristics, with 6 EOG-CG retrospective/cross-sectional comparisons. Gout diagnosis preceded cardiometabolic comorbidity and renal comorbidities were less prevalent in EOG than CG patients. EOG patients had more severe disease (more gout flares, polyarticular disease), higher pre-therapy serum urate (SU), and worse oral urate-lowering therapy response. Genetics-focused publications reported higher incidences of dysfunctional urate transporter mutations in EOG patients. This review suggests that EOG is more recalcitrant to urate-lowering therapy, is associated with urate transporter defects, and carries heavy disease burden. Therefore, early rheumatology referral and urate-lowering in a treat-to-target fashion may benefit EOG patients. Interestingly, EOG patients had fewer cardiometabolic comorbidities at diagnosis than CG patients, presenting a potential "window of opportunity" to attenuate cardiometabolic comorbidity development with SU control. Preventing gout-related suffering and health burden is particularly important in these young EOG patients who will live with gout and its sequelae for decades. Gout, an inflammatory arthritis caused by high urate levels in the blood (SU), is associated with medical issues, including heart disease, high blood pressure, type 2 diabetes, and kidney disease. Millions of Americans have gout, with some having early-onset gout (EOG), generally the first gout attack at or before 40 years of age. Little information on EOG has been published; this literature review provides insight. More recent articles and major rheumatology meeting presentations (2016 to August 2022) on EOG were reviewed. Publications that were duplicates, not in English, on a single patient, or were not relevant/did contain enough information were excluded. The age at gout diagnosis determined if patients had common gout (CG) or EOG. Of the 283 publications identified, 17 were included in this review. Gout-associated medical issues (heart, metabolic, and kidney-related) were less common in EOG than CG patients and occurred after gout diagnosis in EOG patients. Compared to CG patients, EOG patients more often had severe gout (more gout attacks and affected joints), higher SU, and worse response to oral SU-lowering medications. Genetics-focused publications showed that mutations affecting how urate is removed from the body are more common in EOG patients. Overall, the literature suggests that EOG may be difficult to treat, has a genetic component, and has a heavy disease burden. Therefore, early rheumatology referral and gout management may benefit EOG patients due to a potential "window of opportunity" where proper SU control may prevent gout-related suffering and health burden in young EOG patients who will live with gout and its consequences for decades.