Effects of Weight-loss Treatment in Obese Patients With Psoriatic Arthritis

BACKGROUND Psoriasis is a common skin disease affecting around 2-3% of the population in Sweden. Approximately 20-30% of the individuals with psoriasis develop psoriatic arthritis (PsA). PsA mainly engage the musculoskeletal apparatus and causes inflammation of joints, tendons and ligaments, but the disease also increases the risk of developing anterior uveitis and inflammatory bowel disease, especially Crohn's disease.

Both psoriasis and PsA are strongly associated with obesity and the metabolic syndrome (Mets). Observational studies have reported a frequency of obesity (body mass index; BMI≥30 kg/m2) in 45% and of MetS in 30-45% of PsA patients. Earlier studies have shown that obesity increases the risk of developing both psoriasis and PsA and that obesity is associated with increased disease activity, poorer treatment response and lower chance of achieving minimal disease activity.

Although the association between PsA and obesity is well known, there are only a small number of interventional studies which have assessed the effects of weight loss on disease activity in PsA.

Patients with PsA also have an increased risk of cardiovascular disease. [12, 13] Chronic inflammation, which accelerates the atherosclerotic process, in combination with a higher prevalence of cardiovascular risk factors among PsA patients is believed to contribute to this increased risk.

Obesity causes a low grade systemic inflammation via the production of pro-inflammatory mediators in the white adipose tissue, such as adipokines and cytokines (e.g. tumour necrosis factor-α and interleukin-6), which are also involved in the pathogenic process if PsA. Obesity-related inflammation could thus act synergistically with autoimmune inflammation in the development and the maintenance of disease in psoriasis and PsA.