Prevalence of coal workers' pneumoconiosis in China: a systematic analysis of 2001-2011 studies

Nowadays, coal workers' pneumoconiosis (CWP) is still believed to be the main occupational disease in China. However, information on the exact prevalence of the disease is not available. Therefore, the aims of our investigation were to provide the missing information in China by conducting a systematic evaluation of published data from 2001 to 2011 and to compare the prevalence of CWP with those in other countries. Published reports about the prevalence of CWP were searched from PudMed(English language databases), Foreign Medical Journal Full-Text Service Database (FMJS, English language databases), Chinese Journal Full-Text Database (CJFD, Chinese language databases), Chongqing VIP Chinese Science and Technology Journals Database (VIP, Chinese language databases), Chinese Biomedical Literature Database (CBM, Chinese language databases) and Chinese Medical Association Journals Database (CMAJ, Chinese language databases). The quality of identified reports was strictly evaluated using predetermined inclusion and exclusion criteria. Based on these criteria, 11 reports were selected. Then, the content of these reports were reviewed and the needed information was extracted. Meta-analysis was performed on the extracted data. The R2.15.1 software was applied for statistical analysis. The total populations from these reports were 173,646 and 10,821 for dust-exposed coal workers and patients with CWP, respectively. The pooled prevalence of CWP was 6.02% (95% CI: 3.43-9.26%) and the pooled rate of CWP patients combined with tuberculosis was 10.82% (95% CI: 8.26-13.66%). The prevalence was analyzed according to the geographic areas of the study, years of the investigation, duration of dust exposure, coal rank, stages of CWP, types of work and coal-mining categories, etc. Among them, the prevalence of CWP in locally owned mines (9.86%; 95% CI: 1.25-25.17%) was significantly higher than that of state-owned mines (4.83%; 95% CI: 2.35-8.13%) (P<0.05). Publication bias was assessed by the Egger's test which showed insignificant results (P>0.05). It was concluded that the prevalence of CWP were still high in China compared to UK (0.8%, during 1998-2000) and USA (3.2% in 2000s). In addition, the conditions in locally owned mines had caused more CWP than that of state-owned mines. Our data clearly show that regulatory agencies in China need to step up their effort in implementing more rigorous policies to protect coal miners, especially those in locally owned mines.