Chest

Chest

Volume 134, Issue 1, July 2008, Pages 133-138
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Original Research
Interstitial Lung Disease
High-Resolution CT Findings of Parenchymal Fibrosis Correlate With Prognosis in Hypersensitivity Pneumonitis*

https://doi.org/10.1378/chest.07-3005Get rights and content

Background

Histopathologic evidence of fibrosis on surgical lung biopsy has been associated with reduced survival in patients with hypersensitivity pneumonitis (HP). Changes of pulmonary fibrosis detected on CT may also correlate with prognosis in patients with HP.

Methods

We identified 69 consecutive patients with HP diagnosed between January 1997 and December 2002 at Mayo Clinic, Rochester, MN. Patients were stratified into fibrotic and nonfibrotic groups based on the CT findings. Fibrosis was defined by the presence of irregular linear opacities, traction bronchiectasis, or honeycombing.

Measurements and main results

Of 69 patients, 26 were classified as fibrotic and 43 as nonfibrotic. Patients in the fibrotic group were older, had longer symptom duration, were more likely to have crackles on auscultation, more likely to be exposed to avian antigen, and had greater restrictive lung impairment (p < 0.05 for all comparisons). There were 11 deaths in the fibrotic group and 1 death in the nonfibrotic group (p < 0.0001). In the regression analysis, CT evidence of fibrosis, more severe pulmonary function abnormalities, and the presence of crackles on auscultation were predictive of reduced survival (p < 0.05 for all). The presence as well as the extent of fibrosis on CT was associated with increased mortality. The age-adjusted hazard ratio for mortality in patients with fibrosis was 4.6 (95% confidence interval, 2.0 to 20.1; p < 0.0001).

Conclusion

CT findings of parenchymal fibrosis are associated with reduced survival in patients with HP and may serve as a useful prognostic indicator.

Section snippets

Patient Population

We conducted a computer-assisted search of the electronic medical records at the Mayo Clinic Rochester, MN, and identified 85 consecutive patients with HP diagnosed during the 6-year period between January 1, 1997, and December 31, 2002. The diagnostic criteria for HP included the following: (1) presence of respiratory symptoms, (2) radiologic evidence of diffuse lung disease, (3) known exposure or a positive serum precipitins to an inciting antigen, and (4) no other identifiable cause for the

Results

The mean (± SD) age in our patient population was 54 ± 14 years and 44 patients were female (64%). In 52 patients (75%), the presumptive antigen was identified by history or serologic testing, and 52 patients (75%) had histopathologic diagnosis of HP. Only one patient was current smoker. Based on the HRCT findings, 26 patients (38%) were classified as fibrotic and 43 patients (63%) were classified as nonfibrotic (Table 1). Patients in the fibrotic group were older, had longer duration of

Discussion

Our study found radiologic evidence of parenchymal fibrosis to be associated with decreased survival in patients with HP. Furthermore, the extent of parenchymal fibrosis, as assessed by semiquantitative visual scoring of CT, correlated with mortality.

HP may lead to progressive clinical deterioration and death in a proportion of patients.5, 10, 11, 12 Mortality in our study was 17%, comparable to reports from other tertiary care referral medical centers.5 The long-term mortality estimates in

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    Funding was provided by the Mayo Clinic Foundation.

    The authors have no conflicts of interest to disclose.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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    Copyright © 2008 The American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.