Effects of immunosuppressants in patients with mild fibrotic hypersensitivity pneumonitis

Background: The efficacy of immunosuppressants in patients with fibrotic hypersensitivity pneumonitis (HP) is controversial. We hypothesized that pretreatment and posttreatment disease progression in immunosuppressant with prednisolone group and the immunosuppressant-naive prednisolone group would show a significant difference.

Methods: This was a single-center, retrospective, observational study. Patients with histopathological examination between January 2005 and March 2021, a diagnosis of fibrotic HP at multidisciplinary discussion and a diagnosis of fibrotic HP according to international guidelines were investigated. Propensity score matching which had covariates: age, gender, and forced vital capacity, was performed, and disease progression between the two groups was compared.

Results: Forty-two patients were included in this study. The mean change in forced vital capacity (FVC) in the 12 months prior to treatment was significantly decreased in the immunosuppressant with prednisolone group compared with the immunosuppressant-naive prednisolone (-8.2% and -2.7%, respectively, P = 0.033). During 12 months of treatment, the two groups did not differ significantly with regards to FVC change (-1.1% and 0.5%, respectively, P = 0.675). Between the two groups, the annual change in Krebs von den Lungen-6 before treatment and after treatment were not significantly different (P = 0.626 and 0.844, respectively). Transplant-free survival from the treatment in the two groups did not differ significantly (HR: 1.09, 95%CI (0.41-2.88), P = 0.873).

Conclusions: No significant differences were observed in FVC changes between the two groups following treatment, although the immunosuppressant with prednisolone group exhibited a greater decrease in FVC before treatment.