The prevalence and unique clinical features of CPFE among patients with connective tissue disease-associated interstitial lung disease: a retrospective, real-world study.

BACKGROUND

Combined pulmonary fibrosis and emphysema (CPFE) is a distinct yet clinically underrecognised syndrome. Interstitial pneumonia is a common pulmonary manifestation of connective tissue diseases (CTDs), and some CTD-interstitial lung disease (CTD-ILD) patients have concurrent emphysema that is frequently overlooked clinically.

OBJECTIVES

This study explored the clinical characteristics and factors associated with emphysema in CTD-ILD patients to guide clinical management.

DESIGN

This single-centre retrospective study included patients with CTD-related lung diseases from the ILD database of Xiangya Hospital. Patients were screened with standardised respiratory disease keywords and verified by chest HRCT. All eligible cases were stratified into CTD-ILD and CTD-CPFE groups based on emphysema presentation on re-assessed HRCT images.

METHODS

Admission data, including demographics, comorbidities, inflammatory biomarkers, autoimmune antibodies, HRCT findings, pulmonary function test results and in-hospital treatment information, were collected for subsequent grouped analysis.

RESULTS

445 CTD-ILD patients were included, and 48 (10.8%) were CPFE. Patients with CPFE were predominantly male (68.8%), had a higher prevalence of a smoking history (68.8% vs 31.2%, p < 0.001), a lower body mass index (BMI) (20.4 vs 22.2 kg/m2, P = 0.004), and a higher prevalence of prior tuberculosis (TB) (14.6% vs 4.3%, p = 0.009). Multivariable regression analysis showed that sex, BMI, smoking status, and history of TB were independently associated with CPFE. Male sex was associated with a markedly increased likelihood of CPFE (p = 0.003). TB was associated with increased likelihood, whereas higher BMI was associated with reduced likelihood (odds ratio: 33 and 0.57, respectively).

CONCLUSION

CTD-CPFE may represent a distinct subgroup within CPFE, with several characteristic features, including a relatively lower prevalence of smoking history. A low BMI and a history of TB were associated with the presence of CPFE, highlighting the potential importance of nutritional and immune status in patients with CTD-ILD.