SP0125 HOW TO ASSESS PATIENT WITH SUSPECTED VASCULITIS

Abstract

Background: Systemic vasculitides are multi-organ, multi-system conditions which can mimic many other diseases. They are rare but very significant because they can rapidly lead to end organ damage or death if left untreated. The difficulty faced by clinicians in diagnosing a patient with vasculitis is further compounded by the presentation of limited forms of vasculitis, which can be difficult to recognise as due to vasculitis, the effects of co-existing co-morbidity and the use of drugs either for medicinal or recreational purposes. Giant cell arteritis is one of the most common serious forms of vasculitis in adults, leading to blindness if untreated. In view of this risk, many clinicians will initiate treatment of any patients with suspected giant cell arteritis before definitive investigations have been performed. Unfortunately this can result in inadequate outcomes form diagnostic tests such as ultrasound or biopsy of the temporal artery. There are no diagnostic criteria for most forms of vasculitis apart from Behcet”s syndrome. Some tests can be very useful in ruling out other causes as well as helping to confirm a diagnosis of vasculitis. We will review some of the strategies for diagnosing vasculitis, complementing a thorough history and examination with selected investigations to improve diagnostic certainty. Objectives: To consider the strategies used to assist the diagnosis of systemic vasculitis; to assess the frequency of multi-system involvement in systemic vasculitis; to critically evaluate the role of diagnostic testing in systemic vasculitis. Methods: A review of current literature on the approach to diagnosis and classification of vasculitis. Results: Table 1 summarises the clinical manifestations of some forms of primary systemic vasculitis, comparing the different frequencies of the common presenting features. Patients with large vessel vasculitis are usually more distinct as a clinical group from other forms of vasculitis but increasingly we see an overlap between GCA and older patients (especially males) with Takayasu arteritis. There is considerable overlap of clinical features amongst the small vessel vasculitides, despite different immuno-pathogenetic pathways. Amongst the anti-neutrophil cytoplasm antibody (ANCA) associated vasculitides (AAV), the presence of active nephritis characterises most patients with MPA; it is less common in GPA and least common in EGPA. Lung involvement is prevalent in all three forms of AAV, but has different characteristics: bronchial wall inflammation with ulceration plus nodules and infiltrates in GPA; transient infiltrates and bronchospasm in EGPA; lung haemorrhage at presentation in MPA, with subsequent risk of developing lung fibrosis. The different patterns of disease activity help in differentiating individual forms of vasculitis, but it is important to remember that many features associated with medication and co-morbidity may make this patient group more homogeneous, especially if the original disease manifestations are now quiescent. We will explore the potential use of classification criteria as substitutes for diagnostic criteria in different forms of vasculitis and evaluate the role of specific tests to assist in the diagnosis, with a focus on ANCA testing in small vessel vasculitis and on imaging in large vessel vasculitis. Conclusion: A rational approach to diagnosis in vasculitis is required, based on a combination of clinical features together with relevant investigations. Diagnostic certainty can vary in the absence of definitive evidence from investigations, especially if patients have already been partly treated prior to completing all relevant investigations. Diagnostic testing is improving and with the development of new criteria for classification, this forms a stronger basis to develop a more sound approach to diagnosis. However, we should always be prepared to apply a provisional diagnosis and reconsider any emerging evidence to suggest an alternative condition.