Diagnostic accuracy of the nasal obstruction index in detecting adenoid hypertrophy in children without allergy

Objective: We have previously compared the capacity of the nasal obstruction index (NOI) and nasal fiberoptic endoscopy (NFE) to detect adenoid hypertrophy (AH) in children and found no agreement between them. However, the prevalence of false positive results was significantly higher in children with allergic rhinitis (AR), thus suggesting that AR may be a possible causative factor. The aim of this study was to verify the diagnostic accuracy of the NOI in detecting AH by comparing NOI scores with NFE findings in a selected series of non-allergic children affected by nasal obstruction. Methods: This prospective study was carried out at the Outpatient Clinics of the Departments of Specialist Surgical Sciences and Maternal and Pediatric Sciences of the University of Milan, Italy, and involved 154 non-allergic children aged 3-12 years in whom otological diseases and/or perceived nasal obstruction led to the suspicion of adenoid obstruction. The diagnostic accuracy of NOI was tested at all of the thresholds obtained by combining all of the cut-off points of NFE and NOI. Results: Sixty-two percent of the children had otological diseases. The choanal opening was completely blocked by the adenoids in 40% of the children, whereas NOI indicated severe clinical obstruction in only 16%. The analysis of diagnostic accuracy showed that sensitivity and specificity were respectively 17-96% and 15-91% depending on the threshold, with no simultaneously acceptable sensitivity and specificity values at any threshold and AUC values of ≤0.7 at all thresholds. Conclusions: In comparison with NFE, the NOI seems to be inaccurate in detecting AH in non-allergic children with nasal obstruction.