Table 1

Risk of breast cancer among female users of H2 blockers in GHC relative to the general population of western Washington State, 1977–1996

ObservedExpectedSIR95% CI
All users507518.21.00.9–1.1
Time since cohort entry (mo)
  0–116876.80.90.7–1.1
 12–59223234.81.00.8–1.1
 60–119154149.81.00.9–1.2
120+6256.81.10.8–1.4
By type(s) of H2 blocker used
Cimetidine only267281.80.90.8–1.1
Time since cohort entry (mo)
  0–113042.00.70.5–1.0
 12–59118122.51.00.8–1.2
 60–1198384.31.00.8–1.2
120+3633.01.10.8–1.5
Cimetidine and other165166.31.00.8–1.2
Time since cohort entry (mo)
  0–112018.21.10.7–1.7
 12–596270.20.90.7–1.1
 60–1195854.81.10.8–1.4
120+2523.21.10.7–1.6
Other only7570.01.10.8–1.3
Time since cohort entry (mo)
  0–111816.61.10.6–1.7
 12–594342.21.00.7–1.4
 60–1191310.71.20.6–2.1
120+10.61.70.0–9.4