Confounding by indication?
Shapiro
S
S
D002927:Cimetidine / Q000009:adverse effects; D015986:Confounding Factors, Epidemiologic; D006635:Histamine H2 Antagonists / Q000009:adverse effects; D006801:Humans; D011899:Ranitidine / Q000009:adverse effects; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000453:epidemiology*
D006635:Histamine H2 Antagonists; D002927:Cimetidine; D011899:Ranitidine