Prognostic relevance of autoantibodies in patients with hypersensitivity pneumonitis (HP): a German multicentre study.

<bold>Rationale:</bold> Antinuclear antibodies (ANA) positivity has been reported in about 20 % of patients with HP but their prognostic relevance is poorly known. Aim of this study was to investigate the prevalence of ANA and their correlation with disease outcome in HP patients from three different cohorts. <bold>Patients and methods:</bold> A total of 150 consecutive HP patients (74 M and 76 F) from three different cohorts (N=64, N=41 and N=45) were retrospectively investigated. ANA screening was performed using indirect immunofluorescence (IF) on HEp-2 cell line. ANA positivity was set at a titer higher than 1:160. Disease progression was defined as a relative decline in FVC >10% pred. and/or DLCO ≥ 15% pred. and/or worsening of radiological features of HP. <bold>Results:</bold> In the pooled cohort, ANA were positive in a total of 56 patients (37%), without significant differences between the three cohorts. The most frequently observed ANA subtype was Ro-52 (8%), followed by SSA, SSB, PM75, and gp210, each accounting for 3%. ANA positive patients had a significantly shorter time to disease progression compared to those who were ANA negative (17 ±14 months vs 28 ±14 months, respectively, p=0.009). The proportion of fibrotic HP patients across the three cohorts was 76%, 42% and 49% respectively (p<0.001). The multivariate analysis confirmed that ANA positivity was an independent predictor of disease progression in patients with fibrotic HP (HR 2.769, p=0.017). ANA positivity or subtype did not correlate with survival or response to treatment. <bold>Conclusion:</bold> ANA status might potentially be used as a prognostic biomarker of disease outcome in patients with fibrotic HP.