Impact of different diagnostic criteria in hypersensitivity pneumonitis: a center’s experience

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease from exposure to an inducing antigen. Recently, two societies (CHEST and ATS/JRS/ALAT) have published guidelines for HP’s diagnosis. To determine how these guidelines perform in a real-world setting and to identify differences in diagnostic confidence. We applied both criteria to 88 cases of HP previously confirmed (2015-2023). We simplified the diagnostic confidence into four categories for comparison: definitive (≥90%), high(70–89%), low(51-69%) and unlikely HP (≤50%) according to the literature. There were 59 female and 29 male with a median age of 71.0 [66.3;75.0], 14.8% had unknown exposure, 50.0% had restrictive defect, 85.2% underwent LBA (34.1% with lymphocytosis≥30%) and 18.2% lung biopsy. The table summarizes the results of HP diagnostic confidence: <table-wrap><object-id>erj;64/suppl_68/PA1575/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td> <bold>Degree of diagnostic confidence (DDC)</bold> </td><td> <bold>ATS/JRS/ALAT</bold> <bold>[n(%)]</bold> </td><td> <bold>CHEST</bold> <bold>[n(%)]</bold> </td><td> <bold>p value; Kappa’s Cohen (<italic>p</italic>value)</bold> </td></tr><tr><td><bold>Definitive</bold></td><td>3(3.4%)</td><td>19(21.6%)</td><td> <0.001; 0.13 (0.116) </td></tr><tr><td><bold>High</bold></td><td>57(64.8%)</td><td>25(28.4%)</td><td> <0.001; 0.20 (0.025) </td></tr><tr><td><bold>Low</bold></td><td>20(22.7%)</td><td>35(39.8%)</td><td> 0.017; 0.11 (0.310) </td></tr><tr><td><bold>Unlikely</bold></td><td>8(9.1%)</td><td>9(10.2%)</td><td> 1.00; 0.41 (0.003) </td></tr></tbody></table></table-wrap> When definitive and high confidence were considered together (DDC≥70%; 60 and 44 patients), as well as low and unlikely confidence (DDC<70%; 28 and 44), the concordance of the guidelines was moderate (p=0.002|K 0.41 [p<0.001]). Our findings confirm that ATS guidelines are more restrictive in determining a definitive HP diagnosis as stated in literature. Moreover, the agreement between guidelines was poor/fair for definitive/high/low confidence categories but the concordance was improved when 70%confidence level was considered for appropriate management of these patients.