Usage and Grammar

Q. I am a copyeditor for a tiny scientific journal. I was given the following sentence: It is intriguing to note that BE has 18- to 33-fold the analgesic potency of morphine. I felt that this was incorrect and should have been changed to “18 to 33 times the analgesic potency” or “an 18- to 33-fold greater analgesic potency.” My editor overruled me by telling me that in scientific writing this is acceptable. I believe he is being confused by the fact that dictionaries give times as the definition of -fold (the true meaning of -fold is quite debatable, but that is not my question). I can’t seem to find a good reference for correct usage in this case. 

A. Careful writers and editors avoid the use of -fold precisely for this reason: it’s ambiguous. From Scientific Style and Format (12.3.3, “-Fold, Factor, and Times”):

the volume increase was 3-fold [was the final volume 3 times as high as the initial volume, or was the size of the increase 3 times the initial value?]

the final volume was 3 times the initial volume
the final volume was 300% of the initial volume
the final volume was 3 times the initial volume of 10 mL