Impact of Lymphocytosis in Bronchoalveolar Lavage Fluid on Corticosteroid Treatment in Fibrotic Hypersensitivity Pneumonitis

• Published in: The Journal of the Japan Society for Respiratory Endoscopy Vol. 44; no. 4; pp. 259 - 267
• Main Authors: Okamoto, Tsukasa, Miyazaki, Yasunari, Ejima, Masaru, Shimamura, Takashi, Suzuki, Takafumi
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society for Respiratory Endoscopy 25.07.2022; 特定非営利活動法人 日本呼吸器内視鏡学会
• Subjects: Bronchoalveolar lavage fluid; Corticosteroid treatment; Fibrotic hypersensitivity pneumonitis; Lymphocytosis; Prognosis; ステロイド; リンパ球分画; 予後; 気管支肺胞洗浄液; 線維性過敏性肺炎
• ISSN: 0287-2137; 2186-0149
• DOI: 10.18907/jjsre.44.4_259

Background and purpose. Bronchoalveolar lavage (BAL) lymphocytosis is considered when deciding whether or not to perform corticosteroid treatment for fibrotic hypersensitivity pneumonitis (HP). However, there is scant evidence as to whether or not the BAL lymphocyte percentage can predict the posttreatment response and prognosis in fibrotic HP. Methods. We conducted a retrospective single-center study of 62 cases of fibrotic HP who had undergone corticosteroid treatment and received a BAL analysis within 1 year before the treatment. The association of the BAL lymphocyte percentage with the posttreatment mortality was evaluated using a multivariate analysis. Treatment responses were compared among the 3 stratified groups with high (≥40%, n=14), medium (10-39%, n=26), and low (<10%, n=22) lymphocyte percentages, in terms of the change in radiological scores, percent predicted forced vital capacity (%FVC), and survival rates from the date of initiating corticosteroids. Results. In the entire cohort, a multivariate Cox proportional regression analysis revealed that a low BAL lymphocyte percentage or medium (10-39%) to low (<10%) lymphocyte percentage was significantly associated with a high mortality, independent of the %FVC and presence of extensive ground-glass attenuation (GGA). There were significant or improving trends in one-year GGA scores and six-month FVCs from baseline in all three stratified groups. In contrast, the significant deterioration of the 1-year fibrosis scores from baseline was observed in the medium (10-39%) and low (<10%) lymphocyte percentage groups, showing poor survival rates compared to the high group (≥40%) (median survival time: not-reached, 69 months; P=0.089, and 37 months; P=0.049, respectively). Furthermore, a subgroup analysis of each of the three groups stratified by the presence or absence of extensive GGA revealed that its absence contributed to poor survival rates in all three groups. Conclusion. A low BAL lymphocyte percentage at the time of corticosteroid treatment in fibrotic HP may predict unfavorable outcomes, including continuous fibrotic progression and high mortality. Careful management may be required for corticosteroid therapy in fibrotic HP patients with a poor prognosis, especially those with a BAL lymphocyte percentage <40% and the absence of GGA.