Objective.Systemic inflammationˆ is assessed through measurement of acute-phase reactants such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). With few exceptions, most randomized controlled trials (RCT) have assessed acute-phase reactants (CRP and ESR) as part of the American College of Rheumatology (ACR) 20 response criteria. As part of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA)–Outcome Measures in Rheumatology (OMERACT) working group, we performed a systematic review of the literature to assess the performance of inflammatory biomarkers in psoriatic arthritis (PsA).Methods.A systematic search of PubMed and Embase was performed. The search included peer-reviewed articles and scientific meeting abstracts about RCT and longitudinal observational studies that assessed systemic inflammation using acute-phase reactants in PsA. Studies were assessed following the components of the OMERACT filter including construct validity, responsiveness, and predictive validity.Results.There were 2764 articles retrieved, and 71 articles were included for this systematic review. Twenty-eight articles reported CRP and/or ESR separately, and the remaining articles reported CRP and/or ESR as part of the ACR response criteria. Studies assessing OMERACT responsiveness provided conflicting reports. Inflammatory biomarkers had construct validity for more active disease. Evidence suggests that an elevation of ESR predicts cardiovascular outcomes.Conclusion.Data regarding assessment of systemic inflammation using acute-phase reactants (CRP and ESR) are limited. There is only weak evidence to support normalization of these biomarkers in predicting good clinical outcomes/remission criteria. The predictive value for cardiovascular outcomes was generally good. Further studies to assess systemic inflammation in PsA using acute-phase reactants and other laboratory biomarkers are needed.