Prevalence of Reduced Mid-Expiratory Flow Among Coal Workers' Health Surveillance Program Participants.

Abstract

Background: Small airways disease is a risk factor for the development of obstructive lung disease and may be present among coal miners without obstructive ventilatory impairment. Our study estimated the prevalence of reduced spirometric mid-expiratory flow among coal miners without obstructive ventilatory impairment.

Methods: Data were from coal miners participating in the Coal Workers' Health Surveillance Program (CWHSP) during 2014-2022 with forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) meeting quality criteria and no missing spirometry parameter values. We defined low forced expiratory flow at 25%-75% (FEF_25%-75%) as < 65% predicted.

Results: The prevalence of FEF_25%-75% < 65% predicted among miners without obstructive ventilatory impairment was 7.1% overall, 10.7% among retired miners, and 16.8% among miners with radiographic evidence of coal workers' pneumoconiosis (CWP).

Conclusions: Among miners without obstructive ventilatory impairment, reduced mid-expiratory flow was more prevalent in older miners with longer tenure, specifically retired miners. From a surveillance perspective, reduced spirometric mid-expiratory flow can be an early indicator of more serious health problems in coal miners, including obstructive lung disease.