title: Elevated serum liver enzymes and fatty liver changes associated with long driving among taxi drivers.
abstract: BACKGROUND
  Previous studies suggested increased morbidities and mortalities of liver diseases in drivers.
  
  
  METHODS
  To examine whether driving (monthly driving distance; tenure) is associated with elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), or chronic fatty liver (FL) changes, we performed a cross-sectional, secondary analysis of the Taxi Drivers' Health Study (n = 1,355), adjusting for clinical, demographic, and lifestyle factors.
  
  
  RESULTS
  Prevalence of elevated ALT, elevated AST, and fatty liver changes were 22.0%, 5.1%, and 9.3%, respectively. Driving distance had a positive association with elevated ALT with a prevalence ratio of 1.35 (95% CI: 0.98, 1.89) comparing the highest versus lowest driving quartile. This association differed by alcohol use, with a corresponding prevalence ratio of 2.08 (95% CI: 1.30, 3.33) among "past/current" drinkers but no association among "never" drinkers. Similar patterns were found for AST, but estimates were less stable. We found a curvilinear response pattern for fatty liver changes; prevalence first increased with years as a taxi driver and then receded in the highest ranges of driving tenure, regardless of the alcohol history.
  
  
  CONCLUSIONS
  Our results provide evidence that long driving is associated with both short-term and chronic liver insults, although alcohol use appears to modify this putative effect.
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, USA. slippmann@unc.edu
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Lippmann
authors.forename: David B
authors.initials: DB
authors.lastname: Richardson
authors.forename: Jiu-Chiuan
authors.initials: JC
authors.lastname: Chen
mesh_terms: D000328:Adult; D000410:Alanine Transaminase / Q000097:blood; D000428:Alcohol Drinking / Q000009:adverse effects; D001219:Aspartate Aminotransferases / Q000097:blood; D001334:Automobile Driving; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D015995:Prevalence; D012307:Risk Factors; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase