SP170
DEFINING LUNG INVOLVEMENT IN ANCA ASSOCIATED VASCULITIS PATIENTS USING HIGH RESOLUTION COMPUTERIZED TOMOGRAPHY

INTRODUCTION AND AIMS: Lung involment in patients with ANCA associated vasculitis (AAV) can clinicaly be non specific or even initially asymptomatic. We suggest that high resolution computerized tomography (HRCT) lung scan allows timely diagnosis of lung involvement, affects treatment decissions and disease severity as measured by BVAS score.

METHODS: Our study included 25 out of 82 AAV patients whom we preformed kidney biopsy thus proving renal involment who had non specific respiratory simptoms and signes and no radiomorpholgical changes on standard chest X-ray image. HRCT lung scan was analysed by experienced radiologist. Our cohort included patients with Granulomatosis with polyangiitis (GPA; n=8) and Microscopic polyangiitis (MPA, n=17). Birmingham vasculitis (BVAS) score was calculated using 2003 version form. Wilcoxon Signed Ranks test was used to compare the difference in BVAS score related to HRCT scan.

RESULTS: HRCT lung scans detected various morphologoical changes in lung parenchyma which do not usually or neccesary have typical clinical presentation, like haemoptysis. Changes in lung parenchyma include: consolidations, ground-glass infiltrations, nodules, cavitations, interlobular septi thickening, lung haemorrhage. In our cohort all of the patients presented with signes of renal failure and only 18 (72%) had serum creatinine levels lower than 500 umol/l. Median of BVAS score including HRCT findings was 21 (IQR=16-23), and when HRCT findings were excluded BVAS score significantly decreased (median of BVAS score 15; IQR=11-20, p<0,001) depending on the morphological change in lung parenchyma. It is also interesting that when we analysed all the patients, those treated with plasma exchange therapy had significantly more findings on HRCT lung scan (p=0.02) which suggests that HRCT scan findings influence treatment decision.

CONCLUSIONS: AAV patients can often have lung involvement without significant clinical presentation which can lead to underdiagnosing of lung damage especially when using only standard chest X-ray. Also kidney damage doesn't always correlate with lung damage. HRCT lung scan can detect earliest signes of lung involment in AAV patients therefore influencing both severity of disease scoring and therapeutical decisions which can have an impact on patient outcomes. Granted that there is a difference in radiation dose between standard chest x-ray and HRCT but unrecognised lung damage in AAV patients can have serious clinical repercusions and should be always considered as a tool in AAV patients.