Study population
This pooled data analysis included adult participants from three previously published studies on OT.11–13 Adult patients were either self-referrals or referred from outside institutions to tertiary-care otorhinolaryngology departments between 2008 and 2018. Inclusion criteria were posttraumatic, postinfectious, and idiopathic smell loss. Exclusion criteria were TDI above 30.5 (indicating normal olfactory function), pregnancy, and acute or chronic sinonasal diseases. At the initial visit, patients were asked for presence of parosmia or phantosmia (binary outcome of yes and no), time since onset of OD (in month), and possible causes for their smell loss. Diagnosis was made based on the recent “Position paper of olfactory dysfunction1” (Table 1 ).