Olfactory testing
Olfactory testing was performed twice birhinally (before and after
training) by means of the validated Sniffin’ Sticks test (Burghart
Medical Technology, Wedel, Germany).14 The Sniffin’
Sticks test is divided into subtests, covering three olfactory
dimensions: (i) Threshold (T), (ii) Discrimination (D), and (iii)
Identification (I). Summed scores allow the categorization of olfactory
performance into normosmia, hyposmia, and functional anosmia based on
normative data of over 9000 healthy subjects.15 The
test procedure is described in detail elsewhere.14Furthermore, Sniffin’ Sticks can also be used for follow-up testing with
minimally clinically important differences defined for summed scores and
each of the subtests separately.16