GOUT GOUT

What is gout? Gout is a painful rheumatic disease. It causes the inflammation of the joints and often starts in the feet or toes. For 70% of sufferers a joint in the big toe is the first to be affected. Gout mainly affects men aged between 40 and 60. It causes acute, intermittent and painful attacks of arthritis in the joints of the foot, knee, ankle, hand and wrist.

Gout is a painful rheumatic disease of the joints often starts in the feet or toes

Gout results from excess blood levels of uric acid. This is a waste product that is produced when proteins are broken down. Normally uric acid is eliminated in the person's urine, but if there is too much uric acid, it forms crystals that get deposited around joints and tendons. This cause serious inflammation, swelling, stiffness and severe pain. It can lead to significant disability in the long term. Gout is on the rise in Canada and other developed countries.

Gout (or gouty arthritis) is caused by a build-up of uric acid crystals in the joints

Who gets gout and hyperuricaemia? In most studies the prevalence of gout is at least 1%. In some countries it is substantially higher—for example, 3.6% in New Zealand Europeans and 6.4% in Maoris. Gout is much more common in men than in women; it is rare before menopause and more common in old age.

Prevalence of gout. Adapted from Mikuls et al.

Factors affecting serum urate concentration **Factors that decrease serum urate concentration: Diet: low fat dairy products. Drugs: xanthine oxidase inhibitors (allopurinol), uricase drugs (rasburicase) and oestrogens. **Factors that increase serum urate concentration: Diet: meat, fish, alcohol, obesity, and weight gain. Drugs: including diuretics, low dose salicylates, cytotoxics, and lead poisoning. Disease: increased purine turnover—chronic haemolytic anaemia, secondary polycythaemia; increased purine synthesis—glucose-6-phosphate dehydrogenase deficiency; reduced renal excretion—hypertension, hypothyroidism, chronic renal disease.

Lifestyle factors have an important effect on the incidence of gout. Incidence was higher in those who were obese or had a higher overall alcohol intake, or both.

Effect of total alcohol intake on relative risk of first attack of gout. Adapted from Choi et al.

Effect of obesity on incidence of first attack of gout Effect of obesity on incidence of first attack of gout. Adapted from Choi et al.

Incidence was also greater in those with higher intakes of meat or fish. Purine rich vegetables had no effect whereas low fat dairy products were protective, possibly due to a uricosuric effect of casein and lactalbumin. Hyperuricaemia is associated with increased cardiovascular risk.

How is gout diagnosed? Identifying urate crystals in fluid from an affected joint is the definitive diagnostic test for the diagnosis of gout. Guidelines exist for clinical diagnosis without joint aspiration.

Six or more of these criteria are needed to make a diagnosis: American College of Rheumatology preliminary criteria for the clinical diagnosis of gout. Six or more of these criteria are needed to make a diagnosis: -More than one attack of acute arthritis -Maximum inflammation developed within one day -Attack of monoarthritis -Redness over joints -Painful or swollen first metatarsophalangeal joint -Unilateral attack on first metatarsophalangeal joint -Unilateral attack on tarsal joint -Tophus (proved or suspected) -Hyperuricaemia -Asymmetric swelling within a joint on radiograph -Subcortical cysts without erosions on radiograph -Joint fluid culture negative for organisms during attack

The important differential diagnosis in the acute situation is septic arthritis. If this is suspected an immediate referral for joint aspiration is indicated. The serum urate concentration may reduce during an acute attack; a normal urate concentration at this point does not rule out a diagnosis of gout.

Preventing gout attacks

A low purine diet and avoiding beer is advised for people who have gout attacks. There are several principal sources of purines that people are suggested to limit or avoid in their diet: Fish : particularly anchovies, fish roe, herrings, mackerel, sardines, shrimps, sprats. Meat : liver, heart, kidney, and sweetbreads. Meat extracts : OXO, Bovril, Broth, stock.

Vegetables high in purines such as peas, beans and mushrooms interestingly don't seem to affect the gout risk, even though for many years it was assumed they might (Choi et al, March 2004) People with a history of gout are advised to drink plenty of fluid, approximately 2 liters per day (non-alcoholic).

Treatment of acute gout

- Non-steroidal anti-inflammatory drugs Non-steroidal anti-inflammatory drugs, specifically indometacin, are the most popular treatment for acute gout in the United Kingdom. - Colchicine Colchicine is the most popular treatment for acute gout in some countries, such as France. - Steroids and adrenocorticotrophic hormone Oral steroids may be a safer alternative to non-steroidal anti-inflammatory drugs or colchicine for the management of acute gout.

- Asymptomatic hyperuricaemia does not require treatment: - Local treatments: *Elevation and rest of the affected joint. *Application of ice to the affected area. - Asymptomatic hyperuricaemia does not require treatment: Urate lowering drugs are usually needed only for patients with frequent attacks of gout.

- Serum urate concentrations can go down during an attack of gout. - The target of interventions to reduce serum urate is to decrease the serum urate concentration to below 0.36 mml/l. - Lifestyle changes: *Lose weight. *Eat one less portion of meat or fish a day. *Drink wine instead of beer. *Drink a glass of skimmed milk a day.

Conclusion

Until recently there has been little new information to inform the diagnosis and management of gout. Now there is a resurgence of interest in improving its management. In existence are new high quality epidemiological data; systematic reviews of existing evidence for treatment; evidence based quality of care indicators; new high quality controlled trials; and the first new gout specific drug to become generally available is likely to come on the market soon. Uricase drugs that break down urate are already available for specific indications; in future similar preparations may become more generally available for patients with intractable gout.

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