Impact of Bariatric Surgery on Moderate to Severe Psoriasis: A Retrospective Nationwide Registry Study

Abstract

Studies of the effects of bariatric surgery on psoriasis are few, with conflicting results. By linking the Swedish National Register for Systemic Treatment of Psoriasis (PsoReg) with the Scandinavian Obesity Surgery Registry (SOReg), individuals with psoriasis who had undergone bariatric surgery in Sweden during 2008 to 2018 were identified, and matched with data for patients with psoriasis in PsoReg. Psoriasis Area Severity Index (PASI) and Dermatology Life Quality Index (DLQI) were compared between the groups. Altogether, 50 operated individuals (median body mass index (BMI) 38.7 kg/m2]) and 91 non-operated individuals (median BMI 33.0 kg/m2) were included. Control of disease at baseline was good in both groups. Linear mixed models showed no significant difference in psoriasis disease burden, measured as changes in mean PASI (ΔPASI) (-1.2, p = 0.43) and DLQI (ΔDLQI) (-2.2, p = 0.34). In summary, this study demonstrated no significant effect of bariatric surgery on psoriasis disease burden in patients with relatively well-controlled moderate to severe psoriasis.

Keywords: Dermatology Life Quality Index; Psoriasis Area Severity Index; Scandinavian Obesity Surgery Registry; Swedish National Register for Systemic Treatment of Psoriasis; bariatric surgery; body mass index; obesity; psoriasis.

Fig. 1

Inclusion of individuals during follow-up (2007 to 2019). (a) Flowchart of included and excluded operated individuals, showing the number of cases of patients with moderate to severe psoriasis with a history of bariatric surgery (surgery group). Unique psoriasis patients are patients with history of no more than 1 bariatric surgery. (b) Flowchart of included and excluded non-operated individuals, showing the number of patients with moderate to severe psoriasis without a history of bariatric surgery (control group). DLQI: Dermatology Life Quality Index; PASI: Psoriasis Area Severity Index; PsoReg: Swedish National Register for Systemic Treatment of Psoriasis; SOReg: Scandinavian Obesity Surgery Registry.

Fig. 2

(a) Psoriasis Area Severity Index (PASI) and (b) Dermatology Life Quality Index (DLQI) at baseline, and at the short-term and the longer-term follow-up, for patients with moderate to severe psoriasis with and without a history of bariatric surgery. The lines in the box-and-whiskers plots represent median values (50^th percentile); the box spans the 25^th–75^th percentile; the lower whiskers denote the minimum values and the upper whiskers denote the 1.5 interquartile range (IQR). Values beyond the whiskers are marked with symbols and are considered as outliers.