Persistent or New Obesity Linked With Gout

People who were obese throughout adult life were at increased risk for developing gout, as were those who gained weight between early adulthood and midlife, a large retrospective study found.

Compared with individuals whose weight remained stable in the normal range during adulthood, the hazard ratio for incident gout was 1.84 (95% CI 1.08-3.14) for those who were obese when young adults and also at midlife, according to Jian-Bo Zhou, MD, of Capital Medical University in Beijing, and colleagues.

In addition, those who gained weight during adult life had 1.65-fold greater risk for developing gout (95% CI 1.19-2.29), the researchers reported online in Arthritis Research & Therapy.

Obesity is a recognized risk factor for gout, which is considered to result from insulin resistance and its effects on urate excretion by the kidney. However, “the influence of weight changes during the transition from early adulthood to midlife and the different weight change patterns in specific age ranges on the incidence of gout in later life remain unknown,” the researchers wrote.

To examine this, they analyzed data from the National Health and Nutrition Examination Survey (NHANES; 2007-2014), which is a representative sample of U.S. adults ages 40 to 74 that includes information on health behaviors and conditions, including weight history. The analysis focused on participants’ weight at age 25 and then 10 years before enrollment in NHANES, which was considered midlife.

Participants were categorized as stable non-obese, with a body mass index (BMI) at both time points below 30; stable obese, with BMIs remaining above that cutoff at both time points; losing weight, with a BMI at younger age being above 30 but declining by midlife; and gaining weight, with normal BMI at the earlier time point but rising above 30 at midlife.

Among the 11,079 individuals included and followed for 10 years, there were 320 cases of incident gout.

BMI category remained the same in 78.2% of participants, the researchers reported. Specifically, 71.7% remained stable non-obese, 6.5% were considered stable obese, 1% were classified as losing weight, and 20.8% as gaining weight.

Comorbidities differed according to weight-pattern group. For instance, diabetes was present in 6.8% of the stable non-obese group, in 15.8% of the losing group, in 24.6% of the gaining group, and in 25.9% of the stable obese group. Hypertension was reported in 33.2% of the non-obese group, in 41.8% of the losing group, in 57.1% of the gaining group, and in 56.5% of the stable obesity group.

Unlike patients who were obese at both time points or at the midlife measurement, there was no increased risk for gout among patients who lost weight during adulthood (HR 0.48, 95% CI 0.09-2.61).

Cumulative incidence over time in the four groups were:

• Stable obese, 4.12% (95% CI 2.53-6.63)
• Losing weight, 0.87% (95% CI 0.15-4.74)
• Gaining weight, 4.19% (95% CI 3.31-5.28)
• Stable non-obese, 1.96% (95% CI 1.58-2.43)

These incidence numbers indicate that “the potential impact of weight gain on the incidence of gout was substantial,” Zhou and team wrote.

They also conducted an analysis in which they estimated the percentages of gout cases that could be avoided with hypothetical different scenarios. They determined that during 10 years of follow-up, if those who had gained weight had become non-obese, an estimated 3.2% (95% CI 0.0-6.3) of actual gout cases could have been avoided, and if the entire population had maintained normal weight, 32.9% of cases could have been prevented.

“Taken together, the findings support that maintaining normal weight over the whole of adulthood is beneficial and reduces the risk of gout among obese individuals,” Zhou and colleagues wrote.

“The significance of developing policies and programs that reduce the prevalence of obesity is underscored by the results of our study,” they concluded. Future clinical trials should examine the long-term consequences of weight-loss interventions.

A limitation of the study was the self-report of weight at age 25 and of gout diagnosis.