OK, I requested the full study from the university library.
I'll try to summarize.
-all from Florida, unknown storage conditions
-spanned from 3 months past exp. date to 35 months past exp. date.
-tested for the actual amount of epinephrine in liquid as administered by EpiPen
All EpiPens 24months old or less contained a minimum of 90% of the labeled dose of epinephrine, even though some solutions were discolored.
Take away: In the case of an anaphylactic reaction, an old EpiPen is better than no EpiPen.
Note 1: In reading the study, "EAI" is Epinephrine Auto-Injector.
Note 2: Take the study with a grain of salt. it can be unwise to make a generalization for all EpiPens from a small sample of 35 EpiPens. As well, Florida may be an environment to test the effects of heat on the storage life of EpiPens, but not the effects of cold on the storage life.
Note 3: Even if we take this data as generalizable for all EpiPens, as Mel pointed out, an EpiPen is not a metered dose inhaler (MDI), like Primatene Mist.