VIENNA — The rising prevalence of gout being reported in the United States and many other parts of the world constitutes in part an indictment of suboptimal physician management of the disease, Michael Doherty, M.D., said at the annual European congress of rheumatology.
“One of the suggestions from several reports in the literature is that part of the increasing epidemic is due, shamefully, to relative undertreatment of gout,” according to Dr. Doherty, professor of rheumatology at the University of Nottingham, England.
The goal of gout treatment is cure. It's a realistic, achievable goal with the drugs available today. And if this were occurring consistently, the small and sporadic increases in the incidence of gout documented during the 1990s would have little impact on the prevalence of active gout.
“If you have a chronic disorder—for example, osteoarthritis, or badly treated gout—then the disease tends to be present for a long time, and a small increase in incidence will have a very large effect upon prevalence by the end of the time studied,” he observed at the meeting sponsored by the European League Against Rheumatism.
One persuasive piece of epidemiologic evidence that this is in fact what has been happening with gout comes from the U.K. General Practice Research Database, a highly regarded national project in which participating primary care physicians directly enter detailed computerized health data on close to 2 million patients in the United Kingdom.
Dr. Doherty noted that, in a recent report analyzing gout trends in the database for 1990–1999, investigators concluded that the overall annual incidence of gout in the United Kingdom remained relatively stable throughout the decade. In contrast, the prevalence of gout in 1999—estimated at 1.4%, climbing to a peak of 7.3% among men aged 75–84—was nearly threefold greater than in a similar national study conducted in the mid-1970s (Ann. Rheum. Dis. 2005;64:267–72).
Particularly disturbing to Dr. Doherty was the investigators' observation that, consistently during the 1990s, only about 30% of U.K. patients diagnosed with gout were on allopurinol or other hypouricemic therapy aimed at preventing recurrent attacks. This indicates that effective treatment strategies are markedly underused. Moreover, this epidemiologic observation also is supported by everyday clinical experience, which shows that despite a correct diagnosis of gout, many patients continue to have gouty attacks and a progression of their disease, he said.
A rising prevalence of gout has been documented in the United States as well. In a 10-year study of a managed care population with more than 4 million enrollees, investigators concluded that among those ages 75 or older, the disease prevalence climbed from 21/1,000 in 1990 to 41/1,000 in 1999. Among the 65–74 age group, the prevalence rose less dramatically, from 21–24 cases/1,000 in 1990–1992 to more than 31/1,000 in 1997–1999 (J. Rheumatol. 2004;31:1582–7).
While epidemiologic studies have not consistently shown an increase in gout incidence in the 1990s, that's likely to change in the future. Levels of many known gout risk factors are climbing, including some that are related to lifestyle. These include hypertension, obesity, insulin resistance, and dyslipidemia, each an independent risk factor for gout as well as a component of the metabolic syndrome, which has reached epidemic levels in western societies.
Two-thirds of the body's circulating uric acid pool is cleared by the kidneys. Hence the growing incidence and prevalence of renal impairment constitute another rising risk factor for gout.
Advanced age is a powerful gout risk factor. It has been suggested, but is as yet unproved, that part of the explanation lies in the age-related increase in osteoarthritis, since osteoarthritic joint inflammation encourages the deposit of crystals. On the other hand, Dr. Doherty said, there is evidence to suggest a negative correlation between rheumatoid arthritis and gout.