New insights into the epidemiology of gout.

Gout is a true crystal deposition disease caused by formation of monosodium urate crystals in joints and other tissues. It is a common inflammatory arthritis that has increased in prevalence in recent decades. Gout normally results from the interaction of genetic, constitutional and environmental risk factors. It is more common in men and strongly age related. A major determinant is the degree of elevation of uric acid levels above the saturation point for urate crystal formation, principally caused by inefficient renal urate excretion. Local joint tissue factors may influence the topography and extent of crystal deposition. Recent studies have provided information on dietary risk factors for gout: higher intakes of red meat, fructose and beer are independently associated with increased risk, whereas higher intakes of coffee, low-fat dairy products and vitamin C are associated with lower risk. Several renal urate transporters have been identified including URAT1 and SLC2A9 (GLUT9) and polymorphisms in these genes are associated with an increased risk of hyperuricaemia and gout. Many drugs influence serum uric acid levels through an effect on renal urate transport. Comorbidities, including the metabolic syndrome and impaired renal function are common in gout patients. The usual initial presentation of gout is with rapidly developing acute inflammatory monoarthritis, typically affecting the first MTP joint. If left untreated it may progress with recurrent acute attacks and eventual development of chronic symptoms and joint damage. New knowledge of the modifiable risk factors for gout can be integrated into the management strategy to optimize long-term patient outcomes.