Article Text
PDF
Abstract
Introduction and objectives An association between silicosis and mycobacterium disease is well reported globally particularly amongst gold miners.1 The rate of mycobacterium infection in silicosis cases in the last 15 years in the UK is unclear. The aim of this study was to establish the frequency of either tuberculosis (TB) or non-tuberculous mycobacterium (NTM) disease in a UK cohort.
Methods An occupational lung disease database (2004–2017) identified those with an MDT diagnosis of silicosis. Case notes were examined.
Results 22 patients were identified. 100% men, mean age 59.1 years (24–83) and mean length of silica exposure of 23.0 years (2–51). 63.6% were current or ex-smokers with a mean pack year history of 27.1 pack years (5–40). Figure 1 shows the relevant occupational history. 5 (22.7%) had an obstructive pattern of spirometry, 5 (22.7%) restrictive, 5 (22.7%) mixed and 7 (31.9%) normal spirometry. Mean FEV1 was 79% predicted (29%–106%) at presentation and FVC 90% predicted (48%–116%). 36.4% of patients had evidence of progressive massive fibrosis on chest radiology at presentation. 18.2% of patients were classified as accelerated silicosis (onset within 10 years of exposure). 19 of 22 (86.4%) silicosis cases identified had actively been screened for TB. 6 of 22 (27.3%) received anti-mycobacterium treatment. 5 of 6 received empirical treatment for TB prior to a diagnosis of silicosis being confirmed, of these 2 later relapsed and had NTM confirmed and treated. The other patient received empirical treatment for TB while awaiting lung transplantation and subsequently died of pulmonary TB. 3 of 6 had NTM grown on at least one occasion.
Occupations. n=22.
Conclusion This study indicates that rates of TB and NTM in silicosis are relatively high, supporting previously published international data. In addition, this study also highlights the difficulty in diagnosis of TB/NTM in silicosis due to similar clinical and radiological features, frequently leading to patients being treated empirically for TB and high relapse rates. The need for lung transplantation in accelerated disease may also necessitate careful screening for TB/NTM.
Reference
Cowie RL. The epidemiology of tuberculosis in gold miners with silicosis. Am J Respir Crit Care Med 1994;150(5 pt 1):1460–1462.