Factors Determining the Severity of Pulmonary Function Impairment in Silicotic Patients Nitipatana Chierakul MD*, Tiraporn Boonyarattaphun MD*, Arth Nana MD*
* Division of Respiratory Disease and Tuberculosis, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok
Affiliation : Objective : Silicosis is the most common occupational lung disease in Thailand. Determinants of pulmonary
function impairment in Thai silicotic patients have not been mentioned before.
Materials and Methods : The present study was conducted in silicotic patients who attended the Siriraj Occupa-
tional Lung Clinic in the year 2006. Patients were classified according to the forced expiratory volume in
one second (FEV1) into the severe impairment group (< 50% predicted) and the non-severe group (FEV1 >
50% predicted) which includes normal FEV1. Comparison between the two groups in terms of demographic
characteristics, smoking history, history of pulmonary tuberculosis, and radiographic features were assessed.
Results : Thirty-four patients of which 24 were female (70.6 %) had an overall mean age of 53.7 years. Seven
patients (20.6%) had severe impairment, four were female, three were smokers, and two had a history of
pulmonary tuberculosis. All of the severe impairment patients had nodule profusion in category 2 and had
large opacity. Only the presence of large opacity was significantly associated with the severity of pulmonary
function impairment (p = 0.002).
Conclusion : Only the presence of large opacity in a chest radiograph can determine the severity of pulmo-
nary function impairment in Thai silicotic patients.
Keywords : Silicosis, Chest radiograph, Pulmonary function
