DESTIN, FLA. — The incidence of gout is on the rise, and lifestyle factors are largely to blame, Dr. N. Lawrence Edwards said at the annual Rheumatology on the Beach.
For example, one study showed that between 1977–1978 and 1995–1996, the annual rate of primary gout more than doubled, from about 16 cases/100,000 population to nearly 42 cases/100,000 population. Factors that appear to play a role in this incidence spike are greater longevity, widespread diuretic and aspirin use, hypertension incidence, obesity, metabolic syndrome, and dietary trends, said Dr. Edwards, professor and vice chairman of the department of medicine at the University of Florida, Gainesville.
Weight reduction, decreased alcohol consumption, and reduced intake of purine-rich foods (which have been linked with gout) will reduce urate levels only by about 1 mg/dL. Medical treatment should be considered early in patients presenting with acute attacks, he said.
Urate-lowering therapy, which 15 years ago was reserved for use in patients with chronic gout, now is considered warranted following the first one or two acute attacks.
Uricosuric agents, such a probenecid, and the xanthine oxidase inhibitor allopurinol are used for reducing urate levels, but uricosuric agents increase the risk of uric acid crystallization in the urine and associated stone formation. There are a number of other agents, such as ampicillin, penicillin, cephradine, heparin, and rifampicin, that can potentially affect the action of uricosuric agents, Dr. Edwards said.
Allopurinol, which is a purine analog that is both a substrate and inhibitor of xanthine oxidase, is effective both for people who overproduce and for those who underexcrete xanthine oxidase. The drug also has the convenience of single daily dosing, and it can be efficacious in patients with renal insufficiency.
However, allopurinol isn't always effective for achieving target serum urate levels and concerns about intolerance based on reports of severe hypersensitivity syndrome, rash, gastrointestinal problems, increases in liver enzymes, and bone marrow suppression, tend to scare physicians away from prescribing higher doses, he noted.
As with uricosuric agents, drug-drug interactions also are a problem with allopurinol.
Keys to effective treatment with this drug include dosing allopurinol to achieve a serum urate level between 5.0 and 6.0 mg/dL, which allows reduction of total body urate pool and mobilization of deposited crystals, Dr. Edwards said, stressing the need to start at a low dose of 50–100 mg/day, with close monitoring of escalation.