Diagnosis, Disease Activity and Prognosis of Psoriatic Arthritis

Psoriatic arthritis (PsA) was once considered a relatively benign disease. However, it has been clearly shown in numerous studies that PsA is progressive with the potential to cause destructive arthropathy in a substantial subset of individuals. Since a higher level of structural joint damage correlates with greater disability, identifying the risk factors for damage progression is key. With our improved understanding of the pathobiology of the disease, an expanded set of targeted therapies has emerged and improved the therapeutic landscape for patients with psoriatic disease. Despite this, clinicians treating PsA patients still face numerous challenges. The lack of biomarkers to assist in making a diagnosis remains one of the biggest unmet needs and likely contributes to the diagnostic delays reported in numerous studies. In addition to the lack of diagnostic biomarkers, there is a paucity of accurate and reliable biomarkers to assess disease activity; acute phase reactants are often normal, even in clinically active disease. Concurrent diagnoses such as fibromyalgia can influence clinical disease activity scores in the absence of inflammation, rendering clinical evaluation less reliable. In contrast, an image-based measure such as ultrasound provides an objective assessment and has gained popularity given its high sensitivity to detect inflammatory lesions, including synovitis, tenosynovitis and enthesitis. In this thesis, we present our identification of predictors of radiographic progression in an Irish ‘real world’ cohort of PsA patients. We noted a discrepancy between ultrasound and clinical evaluation in assessing disease activity in PsA. There was a high prevalence of subclinical inflammation in patients in clinical remission, highlighting the need for better markers of inflammation to complement clinical evaluation. Finally, we present our findings from evaluating a panel of serum biomarkers for the diagnosis, monitoring disease activity, and their role in bone remodelling and axial PsA.