The main goal of this study is to determine optimal cut-off values of adalimumab trough levels corresponding to good clinical response. Determination of these values is necessary to compose a therapeutic algorithm, in which the dosing schedule can be adjusted according to serum trough levels of adalimumab and AAA (anti-adalimumab antibodies). A secondary objective of this study is to further detect and quantify AAA and to correlate them with adalimumab and clinical response in a real life setting cohort of psoriatic patients.