Secukinumab for treatment of nail psoriasis: results from the TRANSFIGURE trial

Abstract

ment of psoriasis by lifestyle interventions (diet/physical activity) compared with control, with a mean change in Psoriasis Area and Severity Index (PASI) of –2 59 [95% confidence interval (CI) –4 09 to –1 09, P < 0 001], in agreement with a previous meta-analysis. The limited change in PASI may be attributable to the small weight loss achieved by lifestyle interventions, but there is evidence of a linear dose–response relationship. Bariatric surgery can lead to an additional 16–30% weight loss compared with 5–10% induced by lifestyle. The impact of bariatric surgery on psoriasis/psoriatic arthritis (PsA) has only been studied in a small case series that did not meet the eligibility criteria of the review. On the other hand, two large Scandinavian cohort studies suggested bariatric surgery reduces the risk of developing psoriasis. In one of them, gastric bypass (but not gastric banding) was found to reduce the risk of developing psoriasis (adjusted hazard ratio 0 52, 95% CI 0 33–0 81, P = 0 004) and PsA (adjusted hazard ratio 0 29, 95% CI 0 12–0 71, P = 0 01). As regards PsA, one RCT demonstrated that diet-induced weight loss (≥ 5% of baseline weight) is associated with a greater likelihood (adjusted odds ratio 4 20, 95% CI 1 82–9 66, P < 0 001) of achieving minimal disease activity (MDA) in a dose-dependent manner. In a recently published prospective cohort study, a 640 kcal per day diet for 12–16 weeks led to a median weight loss of 18 7 kg (18 6% of baseline weight) in 41 out of 46 patients with PsA who completed the study, and was associated with a significant improvement in most disease activity parameters in a dose-dependent manner. The percentage of patients with MDA increased from 29% to 54%. Epidemiological studies have provided robust evidence that obesity is a risk factor for incident psoriasis and PsA, aggravates existing psoriasis and PsA, interferes with treatment of those diseases and is associated with decreased drug survival of biologics in psoriasis. Recently published Mendelian randomization studies have provided evidence that higher body mass index (BMI) causally increases the odds of psoriasis by 9% for each unit increase in BMI. Immunological/inflammatory and behavioural mechanisms may contribute to the interplay between obesity and psoriasis, and biomechanical stress can be a contributory factor in PsA. The study by Mahil et al. supports the notion that weight loss may prevent the onset and ameliorate the severity of psoriasis and PsA and provides useful information for dermatologists counselling their patients. The impact of diet-induced weight loss on psoriasis severity is small but significant and dosedependent; gastric bypass can be expected to be more effective in eligible patients, but further studies are required to confirm this hypothesis. Currently, according to the National Institute for Health and Care Excellence guideline, bariatric surgery is a treatment option for people with obesity if they have a BMI of 40 kg m 2 or more, or between 35 kg m 2 and 40 kg m 2 and other significant diseases that could be improved if they lost weight. The article by Mahil et al. justifies the inclusion of psoriasis and PsA among these diseases. Conflicts of interest