Prevalence of Airflow Limitation and Emphysema in Lung Cancer Screening Populations: A Systematic Review and Meta-Analysis.

Abstract

Background: Early detection and treatment of COPD are becoming important for improving the prognosis of individuals who have a history of heavy smoking. Despite the higher risk of COPD among individuals participating in lung cancer screening, many of these patients continue to show rates of underdiagnosis of lung cancer.

Research question: How many participants in lung cancer screening have emphysema or airflow limitation? If spirometry is incorporated into the screening, how many additional patients with airflow limitation could be identified?

Study design and methods: The Ovid-MEDLINE and Embase databases were searched from inception through November 30, 2023. We included original studies reporting the prevalence of CT scan-confirmed emphysema and spirometry-confirmed airflow limitation. The primary outcomes were the prevalence of emphysema and airflow limitation. For studies reporting severity, we analyzed the percentage of mild vs moderate to severe disease. We also calculated the proportion of newly confirmed cases of airflow limitation via spirometry.

Results: In total, 42 studies were included (emphysema, n = 18; airflow limitation, n = 13; both, n = 11), comprising 126,842 individuals with emphysema and 72,209 individuals with airflow limitation. The pooled prevalence of emphysema was 45.3% (95% CI, 39.3%-51.2%), and that of airflow limitation was 40.1% (95% CI, 33.4%-46.8%). Moderate to severe emphysema was observed in 28.8% of patients with emphysema (95% CI, 24.2%-33.4%), whereas 54.3% patients with emphysema (95% CI, 40.6%-60.6%) showed moderate to very severe airflow limitation. Furthermore, 65.2% of patients with airflow limitation (95% CI, 55.7%-74.7%) identified by spirometry had been unrecognized previously.

Interpretation: Among screening participants, 45.3% demonstrated emphysema and 40.1% demonstrated airflow limitation, with 28.8% and 54.3% of these patients showing moderate to severe disease, respectively. Furthermore, 65% of patients with airflow limitation had not received a diagnosis previously. These findings suggest that incorporating spirometry into screening programs may enhance COPD detection and management.

Clinical trial registry: International Prospective Register of Systematic Reviews; No.: CRD42024513248; URL: https://www.crd.york.ac.uk/prospero/.