Chronic hypersensitivity pneumonitis - how to predict the treatment success?

Abstract

Introduction: Hypersensitivity pneumonitis (HP) is the interstitial lung disease with clearly established diagnostic criteria but without pharmacologic treatment recommendations. Most specialists use steroids as first-line drugs, sometimes combined with an immunosuppressive agent.

Methods: We analyzed the treatment outcome defined as a combination of radiologic and functional variables (chest X-ray, VC max, TL,co) and survival in consecutive chronic HP patients treated with prednisone alone or in combination with azathioprine.

Results: The study group consisted of 93 consecutive patients with HP symptoms lasting more than 6 months, of whom 54 (58%) presented with fibrosis in HRCT scan. 49 patients (53%) improved during treatment, 16 (17%) were stable and progression was observed in 28 (30%). Among those with fibrotic HP, progression was noted in 24 cases (45%), whereas among non-fibrotic in 4 (10%) – p=0.00069. Fever after antigen exposure, lymphocyte count in BALF>54%, RV/TLC>120% pred. and ill-defined centrilobular nodules in HRCT were positive treatment outcome predictors (OR 11.8, 8.3, 3.35, 3.1, respectively). Increased eosinophil count in BALF and fibrosis in HRCT predicted negative treatment outcome. Positive response to treatment and preserved baseline VC (% pred.) and TLC (% pred.) predicted longer survival, whereas fibrosis in HRCT was related to a worse prognosis.

Conclusion: Immunomodulatory treatment was effective in significant portion (70%) of patients with chronic HP, including 35% of those with fibrotic changes in HRCT. Lung fibrosis was the strong indicator of bad prognosis in the whole group. Future trials are needed to establish the role of immunosuppressive treatment in cHP.