Determinants of spirometric abnormalities among silicotic patients in Hong Kong.
BACKGROUND
Silicosis is the second commonest notified occupational disease in Hong Kong.


OBJECTIVE
To characterize the determinants of spirometric abnormalities in silicosis.


METHODS
The spirometric patterns of consecutive silicotic patients on confirmation by the Pneumoconiosis Medical Board from 1991 to 2002 were correlated with demographic characteristics, occupational history, smoking history, tuberculosis (TB) history and radiographic features by univariate and multiple regression analyses.


RESULTS
Of 1576 silicotic patients included, 55.6% showed normal spirometry, 28.5% normal forced vital capacity (FVC>or=80% predicted) but reduced forced expiratory ratio (FER<70%), 7.6% reduced FVC but normal FER, and 8.4% reduced both FVC and FER. Age, ever-smoking, cigarette pack-years, industry, job type, history of TB, size of lung nodules and progressive massive fibrosis (PMF) were all significantly associated with airflow limitation on univariate analysis (all P<0.05), while sex and profusion of nodules were not. Only age, cigarette pack-years, history of TB, size of lung nodules and PMF remained as significant independent predictors of airflow obstruction in multiple logistic regression analysis. After controlling for airflow obstruction, only shorter exposure duration, history of TB and profusion of nodules were significant independent predictors of reduced FVC. As well as age, history of TB, cigarette pack-years, PMF and nodule size contributed comparable effects to airflow obstruction in multiple linear regression analyses, while profusion of nodules was the strongest factor for reduced vital capacity.


CONCLUSIONS
In an occupational compensation setting, disease indices and history of tuberculosis are independent predictors of both airflow obstruction and reduced vital capacity for silicotic patients.
Leung
Chi C
CC
Department of Health-Pneumoconiosis Clinic 4/F, Shaukiwan Jockey Club Clinic 8, Hong Kong. cc_leung@dh.gov.hk
Chang
Kwok C
KC
Law
Wing S
WS
Yew
Wing W
WW
Tam
Cheuk M
CM
Chan
Chi K
CK
Wong
Man Y
MY
D000328:Adult; D000368:Aged; D004391:Dust; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006723:Hong Kong; D006801:Humans; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D012044:Regression Analysis; D012822:Silicon Dioxide / Q000633:toxicity*; D012829:Silicosis / Q000209:etiology / Q000503:physiopathology*; D012907:Smoking / Q000009:adverse effects; D014376:Tuberculosis / Q000150:complications; D014797:Vital Capacity / Q000502:physiology
D004391:Dust; D012822:Silicon Dioxide