Establishing utility values for the 22-item Sino-Nasal Outcome Test (SNOT-22) using a crosswalk to the EuroQol–five-dimensional questionnaire–three-level version (EQ-5D-3L)

Background

Chronic rhinosinusitis (CRS) is a common condition for which there are numerous medical and surgical treatments. The 22-item Sino-Nasal Outcome Test (SNOT-22) is a patient-reported outcome measure often used with patients diagnosed with CRS. However, there are no utility values associated with the SNOT-22, limiting its use in comparative effectiveness research. The purpose of this study was to establish utilities for the SNOT-22 by mapping responses to utility values associated with the EuroQol–5-dimensional questionnaire–3-level version (EQ-5D-3L).

Methods

This study used data collected from patients diagnosed with CRS awaiting bilateral endoscopic sinus surgery in Vancouver, Canada. Study participants completed both the SNOT-22 and the EQ-5D-3L. Ordinary least squares was used for 3 models that estimated the EQ-5D-3L utility values as a function of the SNOT-22 items.

Results

A total of 232 participants completed both the SNOT-22 and the EQ-5D-3L. As expected, there was a negative relationship between the SNOT-22 global scores and EQ-5D-3L utility values. Adjusted R² for the 3 models ranged from 0.28 to 0.33, and root mean squared errors between 0.23 and 0.24. A nonparametric bootstrap analysis demonstrated robustness of the findings.

Conclusion

This study successfully developed a mapping model to associate utility values with responses to the SNOT-22. This model could be used to conduct comparative effectiveness research in CRS to evaluate the various interventions available for treating this condition.

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