title: Correlation between Silica Exposure and Risk of Tuberculosis in Lorestan Province of Iran.
abstract: BACKGROUND
  Tuberculosis is considered a prevalent and hazardous disease in developing countries. Recognition and control of TB risk factors are of special significance. This study sought to determine the frequency of occupational silica exposure in TB patients residing in Lorestan Province.
  
  
  METHODS
  This cross-sectional study was conducted in 2012. List of registered TB patients was obtained from the Infectious Disease Control Center of Lorestan Province. Data were collected from 871 TB patients through interview and filling out a checklist. Also, 429 subjects presenting to Health Centers of Lorestan Province with respiratory complaints suspicious of TB (which was ruled out) were entered the study as the control group for comparison of frequency of silica occupational exposure. Understudy subjects based on the degree of silica exposure were categorized into 4 groups of no exposure, mild exposure, moderate exposure and severe exposure and compared in terms of frequency of TB incidence.
  
  
  RESULTS
  Frequency of silica exposure was significantly higher in TB patients compared to controls (P < 0.001, OR: 3.39, 95%CI = 2.63-4.36). Additionally, frequency of TB was greater in patients with probable silicosis and silica exposed subjects compared to those with no history of silica exposure (P < 0.05). Logistic regression analysis revealed significant associations between moderate and severe silica exposure and TB frequency. Significant correlations were also detected between age, work experience, level of education, male gender and cigarette smoking with TB frequency (P < 0.05).
  
  
  CONCLUSIONS
  The study results revealed that silica exposure was prevalent among TB patients and frequency of TB increased by increased intensity of silica exposure, older age, higher work experience, lower level of education, male gender and cigarette smoking. Provided that our study results are confirmed by prospective studies, TB screening is recommended for workers with occupational silica exposure particularly those with higher work experience.
authors.affiliation: Department of Occupational Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Aliakbar
authors.initials: A
authors.lastname: Yarahmadi
authors.affiliation: Department of Pulmonary Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Zahmatkesh
authors.affiliation: Department of Occupational Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Ghaffari
authors.affiliation: Department of Occupational Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Saber
authors.initials: S
authors.lastname: Mohammadi
authors.affiliation: Department of Occupational Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Yasser
authors.initials: Y
authors.lastname: Labbafinejad
authors.affiliation: Chronic Respiratory Diseases Research Center (CRDRC), Air Pollution, Health and Occupational Diseases Research Unit, National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Seyedmehdi
authors.affiliation: Community Medicine Department, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Nojomi
authors.affiliation: Department of Occupational Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mirsaeed
authors.initials: M
authors.lastname: Attarchi
keywords: Occupational exposure; Silica exposure; Tuberculosis; Worker