Measuring psoriatic disease in clinical practice. An expert opinion position paper

Psoriasis is a common, immune-mediated chronic inflammatory disease with a primary involvement of skin and joints, affecting approximately 2% of the population worldwide. Up to one third of patients with psoriasis are diagnosed with psoriatic arthritis (PsA). Psoriasis and PsA are heterogeneous diseases whose severity depends on a number of clinical factors, such as areas affected and pattern of involvement, and are associated with a range of comorbid diseases and risk factors, including obesity, metabolic syndrome, cardiovascular disease and liver disease. Thus measuring the severity of psoriatic disease needs to take into account the multidimensional aspects of the disease. Subjective measures including the impairment in quality of life or in daily living activities as well as the presence of cardio-metabolic comorbidities, are important for the outcome and add further levels of complexity that, to a certain extent, need to be assessed. Because of the wide range of comorbid conditions associated with psoriasis, comprehensive screening and treatment must be implemented for a most effective managing of psoriasis patients. A joint dermatologist–rheumatologist roundtable discussion was convened to share evidence on the real-life use of methods for measuring psoriasis severity comprehensively. Our objective was to provide an expert position on which clinical variables are to be taken into account when considering patients affected by psoriasis and/or PsA globally and on the assessment tools more suitable for measuring disease activity and/or severity in clinical practice.