Screening of olfactory function using the Biolfa olfactory test: investigations in patients with dysosmia

To present a statistical evaluation of a new olfactory test, Biolfa.

The olfactory test was carried out in individuals with normal olfactory function (n=67; 31 males; mean age 27.4 years) and in patients with mild, moderate or severe hyposmia (n=155; 61 males; mean age 54.6 years). The main diagnoses of the hyposmic patients were upper respiratory tract infection (32%), nasal polyposis (24%), head trauma (8%), idiopathic (8%), old age (5%) and chronic rhinitis (5%). In the first part of the test, olfactory thresholds were measured for three different substances (eugenol, aldehyde C14 and phenyl ethyl alcohol). The second part comprised an odor identification test for determining olfactory function for a large panel of common odors of Southern European countries.

Mean olfactory thresholds were determined for subjects with normal olfaction and hyposmic patients; there was a statistically significant relationship between olfactory thresholds and degree of olfaction (mild to moderate hyposmia versus severe hyposmia). For the odor identification test, a global score was determined to allow the differentiation of normosmic subjects from patients with mild, moderate or severe hyposmia. The principles of decision theory (i.e. analysis of the receiver operating characteristic curve) were applied to the problem of evaluating the ability of Biolfa to distinguish subnormal subjects from hyposmic subjects.

This study provides a basis for the routine clinical use of Biolfa.