Assessment of health-related quality-of-life in patients with chronic Rhinosinusitis - Validation of the German Sino-Nasal Outcome Test-22 (German-SNOT-22).

PURPOSE: The Sino-Nasal-Outcome-Test-22 (SNOT-22) represents the reference questionnaire to assess symptoms, health-related quality-of-life (HRQOL) and treatment-response in patients with chronic rhinosinusitis (CRS). The SNOT-22 has been validated for various languages, yet no validation is available for the German version. Thus, we provide a validation of the SNOT-22 for German. METHODS: In this prospective observational study 139 CRS-patients and 36 control-participants were included. CRS-patients completed the German-SNOT-22 before treatment (T0) and four (T1), twelve (T2) and 48 weeks after inclusion (T3). At T0, Mackay-Naclerio-, Lund-Mackay- and Brief-Symptom-Inventory-18 (BSI-18) scores were collected as external reference for the German-SNOT-22 and its subscales. At T1, T2, and T3 health-transition-items (HTIs) were raised to explore responsivity. Control-participants completed the German-SNOT-22 at T0. Reliability (internal consistency, item-total correlation), validity (concurrent validity, discriminatory validity) and responsiveness (distribution- and anchor-based) were explored for the German-SNOT-22. RESULTS: At T0, the mean German-SNOT-22 total-score for CRS patients was 38.0 (± 20.9) and responded to treatment (T1 = 26.3 ± 19.1; T2 = 25.8 ± 20.6; T3 = 20.5 ± 16.3). For control-participants, the mean total-score at T0 was 15.1 (±10.9). The German-SNOT-22 was reliable (excellent internal consistency α = 0.93; good overall item-total correlations r = 0.39-0.85), valid (significant correlations between Mackay-Naclerio-, Lund-Mackay- and BSI-18 scores, all r > 0.39, p < 0.01) and responsive (significant correlations between HTIs and mean change in German-SNOT-22 total-score F = 9.57, p < 0.001). CONCLUSION: The German-SNOT-22 validated here matches the original SNOT-22. It is a reliable, valid and responsive questionnaire to assess symptoms, HRQOL and treatment-response in CRS-patients. Good psychometric properties were observed.

The SNOT-22 factorial structure in European patients with chronic rhinosinusitis: new clinical insights.

PURPOSE: The sino-nasal outcomes test-22 (SNOT-22) represents the reference questionnaire to assess patients with chronic rhinosinusitis (CRS). As weak correlations between objective CRS parameters and SNOT-22 total score have been observed, factor analyses have aimed to identify underlying factorial structures. However, ambiguous factor loadings and problematic item-domain assignments have resulted. Moreover, such factor analyses have mainly been performed in non-European CRS patients, while European data remain sparse. This study thus sought to address these issues. METHODS: Principal component analysis and confirmatory factor analysis were performed from SNOT-22 questionnaires completed by European CRS patients. Goodness of fit, internal consistencies, and factor loadings were calculated. Item-domain assignment was based on statistical grounds and clinical meaningfulness. Additionally, this study investigated correlations between SNOT-22 domains and external reference criteria, including Lund-Mackay score, Lund-Naclerio score and the brief symptom inventory 18 (BSI-18). RESULTS: One hundred and thirty-four European CRS patients were included. Principal component analysis proposed four SNOT-22 domains ("nasal symptoms", "otologic symptoms", "sleep symptoms", "emotional symptoms"), which explained 63.6% of variance. Observed item-domain-assignment differed from previously proposed item-domain assignments. All factor loadings were > 0.5, except "cough" (0.42) and "facial pain or pressure" (0.49). For confirmatory factor analysis, satisfactory goodness of fit (RMSEA = 0.66; CFI = 0.92; TLI = 0.90) and internal consistencies (Cronbach-α: total score = 0.93; domains = 0.75-0.91) were observed. Significant positive correlations were found between the "nasal symptoms" domain and both the Lund-Mackay score (r = 0.48; p < 0.001) and the Lund-Naclerio score (r = 0.27, p < 0.01). Significant positive correlations were also identified between "emotional symptoms" and BSI-18 total score (r = 0.64, p < 0.001). CONCLUSIONS: Principal component analysis performed for SNOT-22 questionnaires completed by European CRS patients indicated a different item-domain-assignment than previously reported. Confirmatory factor analysis suggested acceptable and clinically plausible psychometric properties for the resulting factorial structure. Significant correlations between the "nasal symptoms" and the "emotional symptoms" domains were observed with objective CRS parameters. The resulting factorial structure with different item-domain assignments may thus be more suitable for European CRS patients.