Among people with obesity, bariatric surgery was linked to a lower risk for psoriasis compared with usual care, according to Swedish researchers.
Bariatric surgery — including gastric bypass, vertical gastroplasty, and gastric banding procedures — was tied to a lower incidence of psoriasis versus usual care (71 surgery cases versus 103 control cases, adjusted HR 0.65, 95% CI 0.47-0.89, P=0.008), reported Cristina Maglio, MD, of the Sahlgrenska Academy at the University of Gothenburg in Sweden, and colleagues.
However, incidence of psoriatic arthritis (PsA) was not associated with bariatric surgery (20 surgery cases versus 26 control cases, aHR 0.71, 95% CI 0.38-1.33, P=0.287), they wrote in Obesity.
“Obesity is a risk factor for both psoriasis and PsA,” the authors highlighted, adding “a high body mass index also has a negative impact on the response to treatment in patients with psoriasis or PsA.”
The researchers collected data on participants from the ongoing Swedish Obese Subjects study: 1,991 who underwent bariatric surgery and 2,018 matched controls. The majority of surgery patients underwent vertical banded gastroplasty (n=1,369), while others underwent either gastric banding (n=376) or gastric bypass (n=265) from 1987 to 2001.
Control participants were provided “conventional nonsurgical obesity treatment,” such as lifestyle modification assistance and professional guidance. All individuals were followed-up with at 6 months after baseline, and nine additional times for a total follow-up duration of 26 years.
Information on psoriasis and PsA were collected from medical records of inpatients and non-primary care outpatient visits, as well as self-reported patient questionnaires. During the 26-year follow-up, a total of 174 patients developed psoriasis, which included 46 who developed PsA.
During the 2-year follow-up period, there was a significant decrease in BMI for surgery patients (-23%, 95% CI -24 to -23) and was sustained at the 10-year follow-up (-17%, 95% CI -17 to -16). Those in the control group did not have a significant change in BMI.
In a comparison of the surgery types, there were no significant differences between gastric banding, gastric bypass, and vertical banded gastroplasty in regards to the prevention of psoriasis, although some prior research has seen a stronger association with gastric bypass, not gastric banding.
“It has been hypothesized that gastric bypass induces remission of psoriasis because of an anti-inflammatory effect meditated by a rapid increase in glucagon-like peptide-1 levels after surgery,” the group wrote.
Independent of bariatric surgery status, smoking (HR 1.75, 95% CI 1.26-2.42, P=0.001) and a longer duration of obesity (HR 1.28, 95% CI 1.05-1.55, P=0.014) was associated with a higher risk of psoriasis.
Although some prior studies have found a link between bariatric surgery with a decreased incidence of PsA, Maglio’s group suggested the lack of association in their adjusted study model “may be due to a lack of statistical power, because only 46 cases of incident PsA were observed in our cohort of more than 4,000 individuals.”
“Another possible explanation is that the role of obesity in modulating the risk of PsA is not as strong as for psoriasis,” they wrote.
One potential limitation to these findings include the type of bariatric surgeries assessed, which mostly assessed vertical banded gastroplasty, and did not include the popular sleeve gastrectomy. Other limitations include the lack of primary care visit information, in which the researchers noted “we might have missed some cases of mild psoriasis followed up by general practitioners unless the information was present in the SOS questionnaires.”
The group highlighted their findings for adding “strength” to previous studies “by confirming this association [between bariatric surgery and psoriasis] in a large prospective intervention trial designed to examine the effect of bariatric surgery on obesity-related comorbidities in comparison with usual obesity care.”
Click here for the American Association of Clinical Endocrinologists’ clinical practice guidelines for the nonsurgical care of the bariatric surgery patient.
The study was supported by an award from the National Institute of Diabetes and Digestive and Kidney Diseases, the Swedish Rheumatism association, the Swedish Research Council, the Wallenberg Centre for Molecular and Translational Medicine at the University of Gothenburg, and the Swedish federal government.
Maglio disclosed no relevant relationship with industry. Two co-authors disclosed relevant relationships with AstraZeneca IMed RIA, AstraZeneca, Johnson & Johnson, and Merck Sharp and Dohme.
F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner