Bariatric Surgery May Decrease Gout Risk

Bariatric surgery has been linked to reduced incidence rates of gout compared to usual care for weight loss, according to research published in the Annals of Rheumatic Disease.

Lena MS Carlsson, MD, PhD, of the Department of Molecular and Clinical Medicine at the Institute of Medicine, the Sahlgrenska Academy at the University of Gothenburg in Sweden, and colleagues conducted a matched, prospective, controlled intervention trial comparing patients who are obese who underwent bariatric surgery and a control group  from the Swedish Obese Subjects (SOS) study.

The SOS trial recruited patients from 25 surgical departments and 480 primary health care centers, from 1987-2001 (ClinicalTrials.gov Identifier NCT01479452). Of all participants, 1982 chose to undergo bariatric surgery, while 1999 patients were matched using 18 variables—including sex, age, weight, waist and hip circumference, systolic blood pressure, and serum total cholesterol, among others—to form a control group.

Identical inclusion criteria were used for both groups. All patients were between 37 and 60 years of age, with a BMI of ≥34 for men and ≥68 for women. The researchers excluded patients who had previous surgery for gastric or duodenal ulcers or bariatric surgery, myocardial infarction in the previous 6 months, ongoing or active malignancy in the previous 5 years, or a history of bulimic eating patterns, drug or alcohol abuse, or psychiatric or cooperative problems.

In the surgery group, participants either underwent gastric banding (n=376), vertical banded gastroplasty (n=1369), or gastric bypass (n=265). Participants within the control group received typical non-surgical obesity treatments, ranging from treatment at all to advanced lifestyle modification.

The primary study end point was mortality. Secondary end points included type 2 diabetes and cardiovascular disease; gout incidence was not considered a predefined end point.

When compared to participants in the control group, participants in the surgery group were younger (49±6 years vs 47±6 years, P <.001), had worse metabolic profiles at baseline, and higher BMI and waist circumference (40±5 vs 42±4, P <.001 and 117±9 cm vs 121±10 cm, P =.005). 

At 2-year follow-up, BMI had decreased by 24% in the surgery group (95% confidence interval [CI], –24 to –23), but no change was observed in the control group (+0.1%; 95% CI, –0.3 to 0.5; P <.001). At 10 years, BMI change from baseline was –17% (95% CI, –17 to –16) in the surgery group and +2% (95% CI, 1-2, P <.001) in the control group.

Bariatric surgery was associated with an overall lower risk of gout over 26 years of follow-up (log-rank P <.001, unadjusted hazard ratio [HR]: 0.66; 95% CI, 0.53-0.82, P  <.001), with a total of 339 gout events occurring in the control group (n=201) and the surgery group (n=138). All 3 surgical procedures performed (gastric banding, gastroplasty, and gastric bypass) were linked to lower incidence of gout when compared to the control group.

After multivariate adjustment was performed, bariatric surgery remained associated with a reduced incidence of gout (HR: 0.60; 95% CI, 0.48-0.75, P <.001), while age, creatinine levels, uric acid (≥ 6.8 mg/dL), hypertension, type 2 diabetes, use of medications associated with gout risk, and alcohol intake at baseline were all linked to an increased risk of gout development. 

Summary and Clinical Applicability

This study performed by Dr Carlsson and colleagues demonstrates that when compared with usual care, bariatric surgery can reduce long-term incidence risk for gout; in an obese cohort with no baseline gout diagnosis, overall incidence was 34% lower in the surgery group compared to the control group.

“There are no previous long-term studies that have investigated the effect of bariatric surgery on gout incidence in obese subjects without previous gout diagnosis,” wrote Dr Carlsson and colleagues.

“The preventive effect of bariatric surgery on the incidence of gout was comparable among subjects with BMI > or ≤40.8, similar to that previously reported for the incidence of type 2 diabetes, cardiovascular disease, and cancer.” Dr Carlsson and colleagues noted that these results support previous findings that criteria outside of BMI should be used to select bariatric surgery candidates. 

Limitations and Disclosures

• Gout incidence was not a predefined end point in the study design
• Gout is often diagnosed and treated in primary care; however, a complete record of primary care visits is not currently available in Sweden, which may have resulted in missed gout diagnoses
• Treatment of acute gout attacks with steroids or non-steroidal anti-inflammatory drugs was not taken into account
• The gold standard for gout diagnosis—detection of monosodium urate crystals in a patients’ joint fluid—is not typically used in clinical practice, leading to the possibility of false-positive diagnoses within the study cohort

Dr Carlsson reports relationships with Astra Zeneca, MSD, and Johnson and Johnson.

Dr Neovius reports receiving grants from Pfizer and Astra Zeneca, as well as relationships with Roche and Itrim.

Dr Rudin reports that a portion of her professor’s salary at The Sahlgrenska Academy at the University of Gothenburg is covered by a grant from AstraZeneca IMed RIA (Respiratory, Inflammation, Autoimmunity) in compensation for advice regarding basic research in inflammation at the company. 

Reference

1. Maglio C, Peltonen M, Neovius M, et al. Effects of bariatric surgery on gout incidence in the Swedish Obese Subjects study: a non-randomized, prospective, controlled intervention trial. Ann Rheum Dis. 2016 Oct 8. doi:10.1136/annrheumdis-2016-209958 [Epub ahead of print].

This article originally appeared on Rheumatology Advisor