Draft

26  Hypersensitivity Pneumonitis

26.1 What this covers

  • Antigen removal (worse prognosis if no antigen is identified - Noguieria et al Pulmonology 2019)
  • Steroids, but weak evidence base (RCT of 36 resulted in improvement in DLCo and FVC at 1 month but no difference at 5 years; matched cohort of 144 showed slower fibrosis progression on CT - esp early fibrosis)
  • AZA, MMF - need to exclude IPF (increased mortality). Less side effects than long-term steroids.

26.2 Learning objectives

  • Antigen removal (worse prognosis if no antigen is identified - Noguieria et al Pulmonology 2019)
  • Steroids, but weak evidence base (RCT of 36 resulted in improvement in DLCo and FVC at 1 month but no difference at 5 years; matched cohort of 144 showed slower fibrosis progression on CT - esp early fibrosis)
  • AZA, MMF - need to exclude IPF (increased mortality). Less side effects than long-term steroids.
  • ? Nintedanib - INBUILD study, progressive fibrosis including 26.1% who had chronic HP

26.3 Bottom line / summary

  • Extrinsic allergic alveolitis - to inhaled organic small particles.
  • CHEST: https://journal.chestnet.org/article/S0012-3692(21)00686-3/fulltext
  • ATS: https://www.atsjournals.org/doi/10.1164/rccm.202005-2032ST
  • ARUP’s panel and what the significance of each result is:
  • Diagnostic algorithm (From ATS)

26.4 Approach

  1. Antigen removal (worse prognosis if no antigen is identified - Noguieria et al Pulmonology 2019)
  2. Steroids, but weak evidence base (RCT of 36 resulted in improvement in DLCo and FVC at 1 month but no difference at 5 years; matched cohort of 144 showed slower fibrosis progression on CT - esp early fibrosis)
  3. AZA, MMF - need to exclude IPF (increased mortality). Less side effects than long-term steroids.
  4. ? Nintedanib - INBUILD study, progressive fibrosis including 26.1% who had chronic HP

26.5 Red flags / when to escalate

  • TODO: List red flags that require urgent escalation.

26.6 Common pitfalls

  • TODO: Capture common errors or missed steps.

26.7 References

  • https://journal.chestnet.org/article/S0012-3692(21)00686-3/fulltext
  • https://www.atsjournals.org/doi/10.1164/rccm.202005-2032ST
  • https://photos.collectednotes.com/photos/5187/200a7dbe-8a3d-4fad-8c21-96b5118ae8b9
  • https://photos.collectednotes.com/photos/5187/6e91d6df-1bd2-4ee0-88e5-d93ce65f487b
  • https://photos.collectednotes.com/photos/5187/272e9096-095f-408b-8837-605c2de59229
  • https://photos.collectednotes.com/photos/5187/0fb15d68-dd72-41e1-a9fb-6aa26c076289

26.8 Source notes

26.8.1 Hypersensitivity Pneumonitis

27 Hypersensitivity Pneumonitis

Extrinsic allergic alveolitis - to inhaled organic small particles.

Recent guidelines:

CHEST: https://journal.chestnet.org/article/S0012-3692(21)00686-3/fulltext

ATS: https://www.atsjournals.org/doi/10.1164/rccm.202005-2032ST

ARUP’s panel and what the significance of each result is:

alt

Nonfibrotic:

alt

Fibrotic: alt

Diagnostic algorithm (From ATS)

alt

40% BAL lymphocytosis is strongly associated.

Treatment:

  • Antigen removal (worse prognosis if no antigen is identified - Noguieria et al Pulmonology 2019)
  • Steroids, but weak evidence base (RCT of 36 resulted in improvement in DLCo and FVC at 1 month but no difference at 5 years; matched cohort of 144 showed slower fibrosis progression on CT - esp early fibrosis)
  • AZA, MMF - need to exclude IPF (increased mortality). Less side effects than long-term steroids.
  • ? Nintedanib - INBUILD study, progressive fibrosis including 26.1% who had chronic HP

27.1 Source materials