Strengths and weaknesses of the study
The present study uses a comprehensive dataset including relevant
olfactory demographics and smell-loss related variables to assess
different factors associated with clinically relevant improvements after
OT. However, this study also has limitations. Firstly, although we were
able to depict the exact training type in all studies, subtle
differences in odours used might have biased our results. Since previous
studies have shown that the training effect was consistent among
different training protocols, these differences might not have affected
the outcome after OT to a large extent.11,12 Secondly,
the missing values may have biased our results and compromised the
statistical power. Nevertheless, our results are an important reference
point on OD-related variables for clinicians during counselling of
patients with smell loss.