Weighing in on obesity and psoriatic arthritis - Time to move beyond association to robust randomised trials

Almost one in two individuals with psoriatic arthritis (PsA) are now living with obesity. Obesity increases the risk of developing PsA, worsens disease activity, pain and fatigue, impairs treatment response, and amplifies the risk of many cardiometabolic comorbidities already more prevalent in PsA. Despite the increasing evidence for the pathogenic role of obesity in PsA, current treatment focuses on immune mediated therapies, with limited attention to tackling excess adiposity. Residual pain and disease activity in PsA can in turn adversely impact physical activity, leading to a cycle of further weight gain and worse disease activity. Preliminary evidence from dietary interventions in patients with PsA and obesity suggests weight loss of≥5% body weight can improve disease activity, holding promise for potentially even better improvements with newer pharmacological anti-obesity therapies, such as incretin-based weight loss medicines, which result in average weight losses of 15-20%. In this narrative review, we provide an overview of the adverse impacts of obesity in PsA and discuss weight loss therapies now available to help address this. We highlight the urgent need for robust randomised controlled trials of weight loss therapies in patients with PsA and obesity to determine their clinical and cost effectiveness in PsA management and to inform where these are best implemented in the disease course and treatment pathway.