A Pietroisti et al. Occ Env Med (2006) Vol.63 p 773-775
“Shift work increases the frequency of duodenal ulcer in H pylori infected workers”
The prevalence of duodenal ulcer was higher in night shift workers than in day time workers; 29% vs. 9%. Odds ratio = 3.9 (95% CI = 2.1 to 7.5).