Weight loss surgery Helps Forestall Gout
Obese individuals who experienced weight loss surgery stood a 34% decreased possibility of subsequently developing gout, a Swedish study found.
During around 26 years of follow-up, there has been 138 new instances of gout among patients who’d the surgery as opposed to 201 cases in the matched, non-surgery group, according to Lena M.S. Carlsson, MD, in the College of Gothenburg, and colleagues.
As opposed to the normal-care control group, individuals who’d a bariatric procedure had an unadjusted hazard ratio for gout of .66 (95% CI .53-.82, P<0.001), the researchers reported online in Annals of the Rheumatic Diseases.
“The beneficial effects of bariatric surgery are not limited to weight loss, but they extend to improvement in metabolic parameters and to lower risk of developing type 2 diabetes, cardiovascular disease, and cancer,” the team wrote.
Studies have also suggested that bariatric surgery can lower serum uric acid levels, and one report suggested that there might be a short-term decrease in attacks among patients with gout.
To assess the long-term effects of the surgery on incident gout among obese individuals without gout at baseline, the researchers analyzed data from the prospective interventional Swedish Obese Subjects (SOS) study, which recruited 4,047 individuals from 1987 to 2001. Among these, 2,010 had the surgery, while the remainder represented controls, who were matched for multiple factors including age, sex, height, weight, waist and hip circumference, blood pressure, cholesterol, smoking, and psychosocial variables.
The surgical procedures were vertical banded gastroplasty in 1,369, gastric banding in 376, and gastric bypass in 265.
Among controls, management strategies included anti-obesity drug treatment and intensive lifestyle modification involving advice on food choices, energy intake, and exercise.
The primary endpoint of the SOS study had been mortality the effect on gout was a post-hoc analysis.
Hyperuricemia was defined as serum uric acid levels of 6.8 mg/dL or higher.
Patients in the surgery group were younger than the controls (age 47 versus 49, P<0.001), and had higher body mass index (BMI), greater waist circumference, and worse metabolic factors such as glucose levels and cholesterol.
Those in the surgery group also more often had diabetes and hypertension, but uric acid levels were similar, at 5.9 to 6 mg/dL. Among controls, 23% had baseline uric acid levels of 6.8 mg/dL or higher, as did 25% of the surgery group (P=0.11).
At 2 years, BMI had fallen by 23% (95% CI -24 to -23) among patients in the surgery group, while there was no change in the control group ( 0.1%, 95% CI -0.3 to 0.5), which was a significant intergroup difference (P<0.001).
By 10 years, changes in BMI were -17% (95% CI -17 to -16) in the surgery group and 2% (95% CI 1-2) among controls (P<0.001).
At 15 years, the difference in absolute risk between the surgery and control groups was three percentage points, and the number needed to treat was 32 (95% CI 22-59).
After multivariate adjustment, the overall hazard ratio for gout among the surgery patients was 0.60 (95% CI 0.48-0.75, P<0.001). Individual factors associated with an adjusted higher risk were:
Age (per 10 years), HR 1.81 (95% CI 1.49-2.19, P<0.001)
Creatinine (per 1 mg/dL), HR 5.95 (95% CI 2.28-15.5, P<0.001)
Uric acid =6.8 mg/dL, HR 3.67 (95% CI 2.89-4.64, P<0.001)
Hypertension, HR 1.43 (95% CI 1.03-1.97, P=0.03)
Type 2 diabetes, HR 1.56 (95% CI 1.19-2.05, P=0.001)
Use of drugs associated with gout, HR 1.39 (95% CI 1.08-1.78, P=0.01) and
Alcohol intake (per 1 g/day), HR 1.02 (95% CI 1.01-1.04, P<0.001).
The researchers also looked at the development of hyperuricemia among individuals who had normal uric acid levels at baseline, and found a 49% lower incidence, with an unadjusted hazard ratio of 0.51 (95% CI 0.43-0.62, P<0.001).
At 15 years, the difference in absolute risk for hyperuricemia was 12 percentage points, and the number needed to treat was eight (95% CI 6-13).
“The mechanisms behind the reduction in serum uric acid levels following bariatric surgery include, among others, the improvement in renal function and insulin resistance, the reduction in serum triglyceride levels, and possibly even diet changes,” Carlsson and colleagues noted.
“These results confirm once more that the beneficial effects of bariatric surgery are not limited to weight loss and that they also extend to the prevention of hyperuricemia and gout.”
Limitations of the study included the fact that the gold standard for gout diagnosis — identification of monosodium urate crystals in joint fluid — is not typically done in clinical practice, suggesting the possibility of false positives, and that gout incidence was not a predefined endpoint in SOS.
The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases, the Swedish “Reumatikerforbundet,” the Swedish Research Council, and the Swedish federal government.