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

Abstract

Background: Early detection and treatment of chronic obstructive pulmonary disease (COPD) are becoming important for improving the prognosis of individuals who smoke heavily. Despite the higher risk of COPD among individuals participating in lung cancer screening, many of these patients remain underdiagnosed.

Research questions: 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 newly identified?

Study design and methods: The Ovid-MEDLINE and Embase databases were searched from inception to November 30, 2023. We included original studies reporting the prevalence of CT-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 versus moderate to severe cases. We also calculated the proportion of newly confirmed airflow limitation cases via spirometry.

Results: In total, 42 studies were included (emphysema, n=18; airflow limitation, n=13; both, n=11), comprising 126,842 individuals for emphysema and 72,209 for 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% (95% CI, 24.2-33.4%) of emphysema cases, while 54.3% (95% CI, 40.6-60.6%) had moderate to very severe airflow limitation. Furthermore, 65.2% (95% CI, 55.7-74.7%) of airflow limitation cases identified by spirometry were previously unrecognized by patients.

Interpretation: Among screening participants, 45.3% had emphysema and 40.1% had airflow limitation, with 28.8% and 54.3% of these cases being moderate to severe, respectively. Furthermore, 65% of airflow limitation cases were previously undiagnosed. These findings suggest that incorporating spirometry into screening programs may enhance COPD detection and management.