Treatment of gout 

Summary points   What is gout   Treatment of gout   Indications for Uric acid lowering therapy   Lifestyle interventions   Pharmacists have a key role in the care of people with gout   Prevalence and impact of gout   References   Issue 8 Contents

What is gout?

Gout is an arthritis caused by the inflammatory response to intra-articular monosodium urate crystals. Supersaturation of urate typically occurs in physiological fluids above concentrations of 0.42 mmol/L. In early disease, gout presents as recurrent episodes of self-limiting acute inflammatory attacks (‘flares’) of arthritis. These attacks most often affect the 1st metatarsophalangeal joint, midfoot and ankle. In the presence of prolonged hyperuricaemia, some patients develop recurrent polyarticular attacks, chronic tophaceous disease, erosive arthritis and renal disease (urate nephropathy and uric acid stones).

Figure 1: An ulcerated tophus of gout (Courtesy of Dr Peter Gow)

Figure 2: Erosive gout

Natural History of Gout

If untreated, the evolution of gout follows four stages:

1. Asymptomatic hyperuricaemia – asymptomatic hyperuricaemia has traditionally remained untreated with drugs. Although evidence is building, linking hyperuricaemia with cardiovascular and renal disease, treatment remains unproven. Identification of hyperuricaemia presents an opportunity to suggest diet and lifestyle changes to patients and also to look for possible underlying causes for the raised uric acid. Of those with hyperuricaemia, 20% will go on to develop acute symptomatic gout.
2. Acute attacks – typically the first attack involves one joint but it can also be polyarticular. Without specific treatment, an attack of acute gout is likely to resolve within 7–10 days. In practice, the severe pain usually forces patients to seek pharmacological relief.
3. Intercritical gout – the length of time between attacks can vary widely. Some patients only ever have one attack, but for the majority, a second attack will occur within a year. If the urate level remains high (>0.36 mmol/L) despite the patient being symptom free, there can be ongoing joint inflammation and hence joint damage and tophi formation.
4. Chronic tophaceous gout – tophi are firm white translucent nodules in connective tissue arising from the deposition of urate crystals. They can take at least 10 years after the initial attack to develop. As well as causing joint destruction, they are disfiguring and also cause physical hindrance. Tophi can become inflamed or infected and can exude tophaceous material.

Diagnosis of gout

Get a quick reference guide for Diagnosis and Treatment of gout here
The diagnosis of gout can be made according to the American College of Rheumatology (ACR)/Wallace criteria¹:

1. The presence of characteristic urate crystals in the joint fluid,
2. A tophus proved to contain urate crystals by chemical means or polarized light microscopy
   
   
   Figure 3: Needle shaped MSU crystals identified within the joint. Viewed under polarizing light with a red compensator.
   
   OR
   
   
3. Six of the following 12 clinical criteria
   1. Maximum inflammation within the first day
   2. More than one attack of acute arthritis
   3. Monoarticular arthritis
   4. Redness observed over joints
   5. First metatarsophalangeal joint pain attack
   6. Unilateral metatarsophalangeal joint attack
   7. Unilateral tarsal joint attack
   8. Suspected tophus
   9. Hyperuricaemia
   10. Asymmetric swelling within a joint on x-ray
   11. Subcortical cysts with no erosions on x-ray
   12. Negative bacterial culture of joint fluid

It is important to note that gout and sepsis can co-exist. The presence of urate crystals in synovial fluid does not exclude a diagnosis of sepsis.²

Although hyperuricaemia is a key risk factor for gout, it is not sufficient to make the diagnosis of gout; only 20% of patients with hyperuricaemia will develop gout, and serum urate concentrations may be normal in patients during an acute gout flare.³

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