Validation of a Novel Allergy-Specific Domain for the 22-Item Sino-Nasal Outcomes Test

Abstract

Objectives: To develop and assess the validity of a novel allergy-specific domain for the 22-item sino-nasal outcomes test (SNOT-22), to provide a new tool that efficiently quantifies the impact of allergic rhinitis (AR) concurrent with chronic rhinosinusitis.

Study design: Prospective validation study.

Setting: Tertiary care hospital and community-based clinic.

Methods: Proposed items were developed based on clinician and patient input, and further assessed via factor analysis and for internal consistency (n = 1987). Items were then additionally assessed for convergent and discriminant validity (n = 415), applying data from concurrent completions of the Nasal Obstruction and Septoplasty Effectiveness Scale (NOSE), Mini-Rhinoconjunctivitis Quality-of-Life Questionnaire (MiniRQLQ), and validated global health assessments. Assessments of intra-rater reliability, responsiveness to change, and qualitative input were also performed.

Results: Factor analysis demonstrated that proposed allergy items mapped to a single domain. Items were internally consistent (Cronbach α: 0.80 within domain, 0.91 within all SNOT). In assessments of convergent validity, domain scores were associated with MiniRQLQ (Spearman's ρ: 0.46, 95% confidence interval [CI]: 0.30-0.59) and NOSE scores (0.36, 95% CI: 0.27-0.44). The novel items also discriminated among clinical states: a 1-point increase in domain score was associated with an 8.32 (95% CI: 5.43-12.75) increase in the odds of prompting a visit for allergy-related symptoms and a 1.52 (95% CI: 1.13-2.05) increase in the odds of positive allergy testing. Intra-rater reliability was substantial (Cohen's κ: 0.8, 95% CI: 0.8-0.9), and responsiveness to change was demonstrated (mean difference: -0.6, 95% CI: -0.8 to -0.4).

Conclusions: This novel domain is a valid, efficient measure of AR alongside rhinosinusitis.

Keywords: allergic rhinitis; chronic rhinosinusitis; evidence-based practice; factor analysis; quality of life; rhinoconjunctivitis; sino-nasal outcomes test; validated instrument.