Women on alendronate or placebo did not know which treatment they were taking, but those on hormone replacement did. This may have contributed to the side effects experienced by women taking hormones, since people who know they are on a medicine watch more closely for side effects. The study therefore had limited ability to compare the side effects of hormone replacement and alendronate. The study could not determine which treatment was most effective in preventing fractures because fractures occur so seldom in non-osteoporotic, younger, healthy postmenopausal women. A much larger study sample would be required to demonstrate a potential protective effect against fractures.