Gout is a chronic disease of deposition of monosodium urate crystals, which form in the presence of increased urate concentrations. Gout is closely related to hyperuricaemia. Urate deposits in the joint, causing joint swelling, pain, movement disorders. Gout affects a significant portion of the population worldwide annually. According to a recent meta-analysis, the prevalence of gout world-wide is 0.6%, while there was marked statistical heterogeneity geographically resulting of a prevalence ranging from \<1% to 6.8%. The frequent attack of gout not only seriously affect the life of patients, but also lead to disability.

There are a few disease states of gout including asymptomatic hyperuricaemia, acute gouty arthritis, intercritical period, and chronic gouty arthritis. Acute flare of gout is characterized by inflamed joint arthritis which peaks within hours with signs of inflammation including redness, hotness, tenderness, swelling and loss of function. The acute attack usually resolves in 2 weeks and the patient enter into a remission phase called intercritical period. There are usually no symptoms during this period, however, proper treatment for hyperuricaemia is needed to prevent further acute attack of gout. Untreated gout or hyperuricaemia will progress into destruction of joints with formation of tophi which are accumulated monosodium urate (MSU) crystals. Joint destruction and deformity are the untreated results of gout, leading to great distress and disability.

The underlying pathophysiology of gout is multifactorial, complex, and poorly understood. It has been found that environment, genetics, immunity, diet, internal environment, trauma and stimulation are involved in the pathogenesis in various degrees. Thus, gout remains one of the major therapeutic challenges. Currently, western medicine treatment of gout flare includes colchicine, NSAIDs and glucocorticoids. These drugs act as analgesics, anti-inflammatory and uric acid lowering drugs. The mechanism of these drugs is to reduce joint inflammation, pain and uric acid level. Besides, management of gout and prevention of acute flares of gout make a crucial part in gout management. To obtain uricemia target, urate lowering treatment (ULT) has been widely used in conventional management of gout. Allopurinol, probenecid and febuxostat are some of the examples of ULT. Although researchers have carried out various studies on this disease, there are severe side effects for patients with gout. For example, Benzbromarone may cause severe renal damage. Moreover, various studies have found a strong association between human leukocyte antigen-B\*58:01 (HLA-B\*58:01) and allopurinol-induced severe cutaneous adverse reactions especially in Han Chinese. With such genetic predisposition, patients may develop toxic epidermal necrolysis, Steven Johnson syndrome and other life-threatening immune-mediated severe cutaneous adverse reactions with allopurinol use. It is reported that the carrier rate of the HLA-B\*58:01 allele was 14% in Han Chinese in Hong Kong. Therefore, it is necessary to explore new treatments for gout with good efficacy and less side effects.

Chinese medicine (CM) is nowadays widely used for managing gout in China and other East Asian countries. In Traditional Chinese medicine (TCM), gout is classified as Bi pattern usually due to Qi stagnation in the meridians and collaterals. Among them, Zhu Liangchun Gout Decoction is one of the most commonly used formulae. Our principal Investigator (Prof. Zhi-xiu Lin), a highly experienced Registered Chinese Medicine Practitioner working at the School of Chinese Medicine, The Chinese University of Hong Kong, has been using a herbal formula (HKIIM-KU formula) to treat patients with gout in Hong Kong for many years. The formula was based on Zhu Liangchun Gout Decoction and has been modified to suit gout patients in Hong Kong. This formula has been observed to be effective in relieving and preventing gout and its related clinical manifestations. Hence, a double-blind, randomized, placebo-controlled, multicenter clinical trial will be employed in this study, and it would be able to provide robust clinical evidence on the efficacy and safety of HKIIM-KU formula for gout.