Perhaps the protocol in the US is different.
However, the AI's are not without serious life limiting side effects
. In particular they do not protect the bones as Tamoxifen does, and I now have osteopenia, requiring a weekly bisphosphonate, Alendronic Acid (Fosamax in the US), plus twice daily Calcichew/Vit.D.
After some 4 yrs on the AI the pain in my left hip, both feet and hands has become unbearable and my GP advised me to stop Arimidex for 3-4 weeks to see if the pain diminished.