Chest
Volume 144, Issue 1, July 2013, Pages 234-240
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Original Research
Diffuse Lung Disease
Clinical Features and Outcomes in Combined Pulmonary Fibrosis and Emphysema in Idiopathic Pulmonary Fibrosis

https://doi.org/10.1378/chest.12-2403Get rights and content

Background

Combined pulmonary fibrosis and emphysema (CPFE) is increasingly recognized, but its prevalence and prognosis remain unclear. We sought to determine the prevalence, clinical features, and prognosis of CPFE in idiopathic pulmonary fibrosis (IPF), using a standardized and reproducible definition.

Methods

Patients with IPF were identified from two ongoing cohorts. Two radiologists scored emphysema and fibrosis severity on high-resolution CT (HRCT) scans. CPFE was defined as ≥ 10% emphysema on HRCT scan. Clinical characteristics and outcomes of patients with CPFE and IPF and those with non-CPFE IPF were compared with unadjusted analysis and then analysis after adjustment for HRCT fibrosis score. Mortality was compared using competing risks regression to handle lung transplantation. Sensitivity analyses were performed using Cox proportional hazards, including time to death (transplantation censored) and time to death or transplant.

Results

CPFE criteria were met in 29 of 365 patients with IPF (8%), with high agreement between radiologists (κ = 0.74). Patients with CPFE had less fibrosis on HRCT scans and higher FVC, but greater oxygen requirements (P ≤ .01 for all comparisons). Findings were maintained with adjustment for fibrosis severity. Inhaled therapies for COPD were used by 53% of patients with CPFE. There was no significant difference in mortality comparing patients with CPFE and IPF to those with non-CPFE IPF (hazard ratio, 1.14; 95% CI, 0.61-2.13; P = .69).

Conclusions

CPFE was identified in 8% of patients with IPF and is a distinct, clinical phenotype with potential therapies that remain underutilized. Patients with CPFE and IPF and those with non-CPFE IPF have similar mortality.

Section snippets

Study Patients

Patients were identified through the University of California San Francisco (UCSF) and Mayo Clinic Rochester (Mayo) interstitial lung disease (ILD) databases between January 2000 and July 2010. Patients were included if they had a diagnosis of IPF based on multidisciplinary review according to established criteria9, 10 and had a high-resolution CT (HRCT) scan within 1 year of their initial clinic consultation. Patients without a HRCT scan available for re-review were excluded (n = 71). A total

Prevalence of CPFE in IPF

Criteria for CPFE were met in 29 of 365 patients, representing 8.0% of the overall cohort (95% CI, 5.1%-10.6%) (Fig 1). There was no difference in the frequency of CPFE between cohorts (8.9% in UCSF and 6.9% in Mayo, P = .50). Forty-nine patients (13.4%) had ≥ 5% emphysema and 106 patients (29.0%) had at least some emphysema detectable on HRCT scan. In 17 patients, the extent of emphysema was greater than that of fibrosis; 15 of these patients met our definition of CPFE. When present, emphysema

Discussion

This is the first IPF-specific multicenter study of CPFE, and unlike previous studies, we used both a standardized definition of CPFE and rigorous statistical methods to determine differences in clinical features and outcomes. We restricted our analysis to patients with IPF to reduce potential bias that would be introduced by inclusion of other ILDs that have distinct natural histories and variable association with smoking. In addition, we chose a prespecified cutoff of ≥ 10% emphysema to

Acknowledgments

Author contributions: Drs Ryerson and Collard had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Ryerson: contributed to conception of the study design, performed the data analysis, produced the initial draft of the manuscript, approved the final manuscript, and served as principal author.

Dr Hartman: contributed to data interpretation and preparation and approval of the final manuscript.

Dr Elicker:

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    Funding/Support: The authors have reported to CHEST that no funding was received for this study.

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