The Epidemiology of Combined Pulmonary Fibrosis and Emphysema (CPFE) Among Mid-Atlantic Veterans.

Abstract

Rationale: Combined pulmonary fibrosis and emphysema (CPFE) is a unique phenotype with important prognosis and management implications in patients with idiopathic pulmonary fibrosis (CPFE-IPF) and other forms of fibrotic interstitial lung disease (CPFE-fILD). However, the epidemiology of CPFE is not well characterized, creating a barrier to clinical research needed to advance our understanding and management.

Objectives: To investigate the incidence, prevalence, and long-term outcomes of CPFE among a regional cohort of Veterans.

Methods: We retrospectively reviewed records for Veterans in the Veterans Affairs Mid-Atlantic Health Care Network (includes North Carolina and Virginia) with International Classification of Disease (ICD)-9 codes for pulmonary fibrosis between January 1, 2008, and December 31, 2015. We stratified pulmonary fibrosis into IPF and fILD using diagnostic codes and chart review. We reviewed CT reports and classified cases as having CPFE according to documented emphysema; a thoracic radiologist overread a subset of scans for validation. We calculated annual incidence and prevalence of CPFE and compared characteristics between Veterans with CPFE and Veterans with fibrosis without emphysema using Chi-squared testing, Mann Whitney U testing, and paired t-tests. We used Kaplan-Meier and Cox models to determine overall survival from diagnosis.

Results: We identified 2,414 Veterans with fibrotic ILD. Among 1,880 Veterans with IPF, 734 (39.0%) had CPFE-IPF; among 534 Veterans with fILD, 194 (36.3%) had CPFE-fILD. Agreement between CT reports and thoracic radiologist review was high (Kappa = 0.78). Annual CPFE prevalence ranged 71-100 per 100,000 Veterans, and incidence ranged 16-39 per 100,000 Veterans. CPFE was associated with male sex, lower BMI, greater tobacco history, higher FVC, reduced FEV1/FVC ratio, reduced DLCO, and increased oxygen utilization. CPFE was associated with increased mortality in unadjusted models. However, after adjustment for age, sex, and BMI, CPFE was not associated survival for both CPFE-IPF versus IPF without emphysema (HR 1.13, 95% CI 0.96-1.33) as well as CPFE-fILD versus fILD without emphysema (HR 1.16, 95% CI 0.82-1.63).

Conclusions: CPFE has high incidence and prevalence among Veterans with IPF and fILD and has a distinct phenotype with diagnostic and therapeutic implications. Further studies are merited investigating diagnosis, treatment considerations, and long-term impacts in CPFE.

Objectives: To investigate the incidence, prevalence, and long-term outcomes of CPFE among a regional cohort of Veterans.

Methods: We retrospectively reviewed records for Veterans in the Veterans Affairs Mid-Atlantic Health Care Network (includes North Carolina and Virginia) with International Classification of Disease (ICD)-9 codes for pulmonary fibrosis between January 1, 2008, and December 31, 2015. We stratified pulmonary fibrosis into IPF and fILD using these ICD9 codes. We reviewed CT reports and classified cases as having CPFE according to documented emphysema; a thoracic radiologist overread a subset of scans for validation. We compared characteristics between Veterans with CPFE and Veterans with fibrosis without emphysema using Chi-squared testing, Mann Whitney U testing, and paired t-tests as appropriate. We used Kaplan-Meier and Cox models to estimate and compare overall survival from diagnosis.

Results: We identified 2,414 Veterans with fibrotic ILD. Among 1,880 Veterans with IPF, 734 (39.0%) had CPFE-IPF; among 534 Veterans with fILD, 194 (36.3%) had CPFE-fILD. Agreement between CT reports and thoracic radiologist review was high (Kappa = 0.78). Overall CPFE prevalence was 107.48 per 100,000, and incidence was 28.53 per 100,000. CPFE was associated with male sex, lower BMI, greater tobacco history, higher FVC, reduced FEV1/FVC ratio, reduced DLCO, and increased oxygen utilization. CPFE was associated with increased mortality in unadjusted models. However, after adjustment for age, sex, and BMI, CPFE was not associated survival for both CPFE-IPF versus IPF without emphysema (HR 1.13, 95% CI 0.96-1.33) as well as CPFE-fILD versus fILD without emphysema (HR 1.16, 95% CI 0.82-1.63).

Conclusions: CPFE has high incidence and prevalence among Veterans with IPF and fILD and has a distinct phenotype with diagnostic and therapeutic implications. Further studies are merited investigating care utilization, treatment considerations, and long-term impacts in CPFE.