Its preferred in older patients because of doctor conservatism more than anything else, because most people under 60, don't have significant risks using sublingual orals at at the lower dosage often prescribed to older TS patients (again conservatism).
Of course, if you have a conditions favorable to a stroke, have smoked a long time, liver problems, genetic predisposition to clotting (like leyden), injection or transdermals are preferred.
Injections are much cheaper than transdermals and in theorie have the same advantages, but tend to lead to spiking in the serum level of E, so even though it goes to the blood, its not used in older individuals (over 50) generally.
