“…[17] In addition to age and sex, the most frequent confounders considered were a history of peptic ulcer (21 studies),[7,11,15–31,35,67] smoking (13 studies),[7,11,15,18,20,21,23,27–32] alcohol use (9 studies),[7,15,19,21,27,28,30–32] use of proton-pump inhibitors and anti-ulcer medications (11 studies),[16–23,30,67,68] and concurrent use of medications increasing the risk of UGIC (16 studies). [7,11,15,16,19–21,23,27,29–31,33,35,67,68] The quality of the studies measured with the NOS was, in general, very good: for the selection component, 12 studies had the maximum score of 4[7,11,15,22–25,32,33,35,67,68] and 13 studies had the next highest score of 3;[13,14,16–19,21,26,28,29,30,32,34] for comparability, 24 studies had the maximum score of 2;[7,11,14–19,21–33,35,67,68] and for the exposure/outcome component, 14 studies had the maximum score of 3[7,11,13,17–19,23–26,33,35,67,68] and 10 studies...…”