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Obesity Doubles Gout Risk, Reduces Age of Onset

August 12, 2011 — Obesity is an independent risk factor for gout and is associated with earlier age at gout onset, according to data reported by Mara A. McAdams Demarco, MS, and colleagues in Arthritis Care & Research.

Ms. McAdams Demarco, who is at Johns Hopkins University in Baltimore, Maryland, told Medscape Medical News, “Overall, gout onset was 3 years earlier on average in those who were obese compared with those who were not obese. Additionally, gout onset was 11 years earlier on average in those who were obese in early adulthood compared with those who were not obese in early adulthood. The relative risk [RR] of gout was nearly double in those who were obese compared with those who were not obese, even after accounting for other risk factors for gout.

“The main implications from this study are that increased adiposity is a strong risk factor for gout and obesity is associated with an earlier age of gout onset. Our results suggest that as the obesity epidemic continues to grow in the US, gout should be considered in the differential diagnosis of acute arthritis in obese adults, regardless of their age,” Ms. McAdams DeMarco added.

The researchers calculated the risk for incident gout by obesity status in patients from the longitudinal, community-based Campaign Against Cancer and Heart Disease (CLUE II) study. They found that 517 of the 15,533 subjects developed new-onset gout during the 18-year study period.

The prevalence of obesity (defined as body mass index ≥30 kg/m2) was 16.2% at baseline. Mean age at gout onset was 59.3 years. Gout onset was 3.1 years earlier (95% confidence interval [CI], 0.3 – 5.8) in subjects who were obese at baseline and 11.0 years earlier (95% CI, 5.8 – 16.1) in subjects where were obese at 21 years of age. “The 18-year adjusted RR of gout in obese participants compared with nonobese participants was 1.92 (95% CI, 1.55 – 2.37),” the study authors wrote.

Hyon K. Choi, MD, PhD, who reviewed the study for Medscape Medical News, said that the link between obesity and the risk for gout has been well established and that any factor that heightens the risk for an event would be expected to cause the event to occur at a younger mean age.

“Furthermore, as this is based only on those cases of gout that occurred during follow-up in this specific cohort, the result does not take into account those who did not develop gout during follow-up (as opposed to the entire population’s experience of obesity vs not). Then, the next question becomes whether the noted time-to-event difference in this specific cohort setting would be applicable and useful in practice,” said Dr. Choi, who is Mary Pack Arthritis Society Chair in Rheumatology, an associate professor in medicine and staff rheumatologist at the University of British Columbia and Vancouver General Hospital in Canada.

“Physicians do consider gout in the differential diagnoses for acute arthritis, regardless of obesity. However, the presence of obesity would increase the probability of gout, as would osteoarthritis,” Dr. Choi said.

Strengths of the study include the scope of the study and the fact that adiposity preceded development of gout. Limitations included reliance on self-report for identifying cases of gout and for heights and weights, as well as inability to quantify alcohol intake.

The link between obesity and gout is thought to be the increased insulin resistance associated with obesity.

Ms. McAdams DeMarco said, “The underlying mechanism linking obesity to gout was not directly tested in this study. However, previous studies have suggested that obesity causes insulin resistance, which may lead to hyperuricemia and thus gout. Insulin resistance is associated with serum urate levels and inversely with renal urate clearance. Additionally, all components of insulin resistance are associated with the development of gout.”

Ms. McAdams Demarco and Dr. Choi have disclosed no relevant financial relationships.

Arthritis Care Res. 2011;63:1108-1114. Abstract

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