Chest
Volume 134, Issue 6, December 2008, Pages 1265-1270
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Original Research
Hypersensitivity Pneumonitis
Clinical Predictors and Histologic Appearance of Acute Exacerbations in Chronic Hypersensitivity Pneumonitis

https://doi.org/10.1378/chest.08-0866Get rights and content

Background

Acute exacerbations (AEs) in idiopathic pulmonary fibrosis (IPF) are critical factors for its clinical course and prognosis. We have seen AEs and poor prognosis consequent to AE in patients with chronic hypersensitivity pneumonitis (HP), as has been seen in patients with IPF. The aim of this study was to evaluate the clinical features of the patients with AE in those with chronic HP.

Methods

We reviewed 100 consecutive patients with chronic bird fancier lung (BFL) from 1993 to 2006, and analyzed the clinical characteristics, including history, and laboratory and immunologic, imaging, BAL, and histologic findings.

Results

AE developed in 14 patients during this observation period (AE group), whereas 86 patients remained stable (non-AE [NAE] group). The 2-year frequency of AE among patients with chronic BFL having usual interstitial pneumonia (UIP)-like lesions seen on surgical lung specimens was 11.5%. Patients with AE were more likely to be smokers (p = 0.003). In pulmonary function test results, the mean total lung capacity (TLC) and diffusing capacity of the lung for carbon monoxide (Dlco) were lower in patients with AEs (TLC: AE patients, 63.0 ± 16.8%; NAE patients, 81.6 ± 20.0%; Dlco: AE patients, 41.9 ± 19.0%; NAE patients, 60.0 ± 19.4%). The mean number of lymphocytes in BAL fluid were lower (AE patients, 13.7 ± 7.5 lymphocytes; NAE patients, 37.2 ± 29.7 lymphocytes), while the number of neutrophils were greater in AE patients (AE patients, 10.7 ± 17.6 neutrophils; NAE patients, 3.6 ± 4.4 neutrophils). Histologic and/or radiologic findings revealed that all AE patients had UIP-like lesions. Diffuse alveolar damage was observed in six cases, whereas organizing pneumonia superimposed on preexistent fibrotic lesions was observed in two cases.

Conclusions

The present study showed several predictive factors for AE at the time of diagnosis. Low TLC and Dlco, low lymphocyte levels in BAL fluid, and a UIP-like pattern in histology at the time of diagnosis may be the risk factors for AE.

Section snippets

Patients

A retrospective review of the medical records of patients with chronic BFL who were admitted to our hospital between April 1993 and November 2006 was undertaken. Most of the subjects were included in the previous article.19 The diagnosis of chronic BFL was made based on clinical, radiologic, and histologic criteria, as was described previously.11, 13, 20 We conducted inhalation provocation tests in 50 of 86 non-AE (NAE) patients and in 10 of 14 AE patients. The remaining patients for each group

Clinical Features in Chronic BFL With AE

The characteristics of the 100 patients with chronic BFL are summarized in Table 1. Fourteen patients (14%) were admitted to the hospital due to the acute deterioration of the disease, and those acute episodes were all consistent with the criteria of Kondoh et al4 for AE (AE group), whereas the remaining 86 patients had experienced no AE during the observation period between April 1993 and November 2006 (NAE group). There was no significant difference in age between AE and NAE patients. AE

Discussion

In this study, the 2-year frequency of AE among patients with chronic BFL who initially had UIP-like lesions was 11.5%, and the mortality rate was 86%. Low TLC and Dlco, fewer lymphocytes, and an increased percentage of neutrophils found in BAL fluid were the characteristics of the AE patients. Moreover, UIP-like lesions at the onset of the diagnosis were an additional risk factor for the development of AE in patients with chronic BFL. Patients who showed peripheral consolidations superimposed

Acknowledgment

We thank Tamiko Takemura, Japan Red Cross Center, for discussions on histopathology and Vernon L. Moore, Merck Research Laboratories (retired), Phillips, WI, for critical review of the manuscript.

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    The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

    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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