Chest
Volume 144, Issue 5, November 2013, Pages 1644-1651
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Original Research
Diffuse Lung Disease
Identifying an Inciting Antigen Is Associated With Improved Survival in Patients With Chronic Hypersensitivity Pneumonitis

https://doi.org/10.1378/chest.12-2685Get rights and content

Background

The cornerstone of hypersensitivity pneumonitis (HP) management is having patients avoid the inciting antigen (IA). Often, despite an exhaustive search, an IA cannot be found. The objective of this study was to examine whether identifying the IA impacts survival in patients with chronic HP.

Methods

We used the Kaplan-Meier method to display, and the log-rank test to compare, survival curves of patients with well-characterized chronic HP stratified on identification of an IA exposure. A Cox proportional hazards (PH) model was used to identify independent predictors in time-to-death analysis.

Results

Of 142 patients, 67 (47%) had an identified IA, and 75 (53%) had an unidentified IA. Compared with survivors, patients who died (n = 80, 56%) were older, more likely to have smoked, had lower total lung capacity % predicted and FVC % predicted, had higher severity of dyspnea, were more likely to have pulmonary fibrosis, and were less likely to have an identifiable IA. In a Cox PH model, the inability to identify an IA (hazard ratio [HR], 1.76; 95% CI, 1.01–3.07), older age (HR, 1.04; 95% CI, 1.01–1.07), the presences of pulmonary fibrosis (HR, 2.43; 95% CI, 1.36–4.35), a lower FVC% (HR, 1.36; 95% CI, 1.10–1.68), and a history of smoking (HR, 2.01; 95% C1, 1.15–3.50) were independent predictors of shorter survival. After adjusting for mean age, presence of fibrosis, mean FVC%, mean diffusing capacity of the lung for carbon monoxide (%), and history of smoking, survival was longer for patients with an identified IA exposure than those with an unidentified IA exposure (median, 8.75 years vs 4.88 years; P = .047).

Conclusions

Among patients with chronic HP, when adjusting for a number of potentially influential predictors, including the presence of fibrosis, the inability to identify an IA was independently associated with shortened survival.

Section snippets

Materials and Methods

From our longitudinal ILD database, as described previously,1 we identified 142 consecutive adult patients with clinical-radiologic-pathologic chronic HP evaluated in our multidisciplinary ILD and occupational medicine program between January 1, 1982, and January 1, 2008. Data from some of these patients were included in two previously published studies.1, 2 We reviewed the complete medical records of included subjects and abstracted data pertaining to the following: demographics, smoking

Results

Of 142 subjects (mean age, 58 ± 12 years; 67 women), 67 (47%) had an IA, and 75 (53%) had no IA. The most common IAs were avian (n = 24, 41%) or mold (n = 16, 27%). Median follow-up for the cohort was 7.8 years. Table 1 displays the clinical characteristics of subjects stratified on survival. At diagnosis, compared with survivors, subjects who died were older, had lower total lung capacity % and Dlco%, had higher severity of dyspnea, were more likely to have fibrosis on HRCT scan and in

Discussion

We identified 142 subjects with well-defined HP evaluated in our program between 1982 and 2008 and evaluated the effect of identifying an IA on prognosis. The main findings of this study were the following: (1) IAs were identified in only 47% of the cohort; (2) IAs were significantly more likely to be identified among survivors than among subjects who died; (3) avian antigens were the most commonly identified IA; (4) inability to identify an IA was a significant predictor of shortened survival,

Acknowledgments

Author contributions: Dr Fernández Pérez is the guarantor of the paper, taking responsibility for the integrity of the work as a whole, from inception to published article.

Dr Fernández Pérez: contributed to conception and design of the study, data collection and analysis, and drafting the manuscript for important intellectual content.

Dr Swigris: contributed to design of the study, data collection and analysis, and drafting the manuscript for important intellectual content.

Ms Forssén:

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  • Cited by (0)

    Funding/Support: Dr Swigris receives funding via a National Institutes of Health K23 Career Development Award [Grant K23 HL092227].

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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