Assessment of the Validity and Reliability of the Sinonasal Outcomes Test-22 in Endoscopic Endonasal Transsphenoidal Pituitary Surgery in a Multicenter Prospective Trial

Introduction: Sinonasal Outcomes Test-22 (SNOT-22) has been widely used as a patient reported sinonasal quality of life (QOL) instrument in patients undergoing endonasal skull base surgery, even though it has never been validated in this patient population. SNOT-22 was developed for chronic rhinosinusitis and consists of five subscales (i.e., rhinological, extranasal rhinologic, ear/facial, psychological, and sleep). The purpose of this study was to explore the psychometric validity and minimally clinically important difference (MCID) of SNOT-22 to determine if it is a valid and reliable scale in patients undergoing endoscopic endonasal pituitary surgery.

Methods: Adult patients with pituitary tumors undergoing endoscopic endonasal transsphenoidal surgery were enrolled in a multicenter QOL study (NCT03014687). Patient-reported sinonasal quality of life was assessed at baseline and at prescribed time points following endoscopic pituitary surgery using SNOT-22 and the anterior skull base nasal inventory-12 (ASK Nasal-12), and a site-specific QOL tool developed and validated in endoscopic endonasal surgery patients. Face validity using factor analysis, internal consistency, responsiveness to clinical change, test–retest reliability, concurrent validity, and MCID were determined for SNOT-22 using standard statistical methods.

Results: A total of 113 patients were evaluated (Table 1). Internal consistency using Cronbach's alpha at baseline and at two weeks were 0.911 and 0.922, respectively, indicating SNOT-22 performed well as a single construct. The mean QOL scores were significantly worse at 2 weeks compared to baseline (16.44 ± 15.07 vs. 23.14 ± 16.43, p < 0.001) indicating the scale is responsive to changes in clinical states. However, only 11/22 (50%) items demonstrated statistically significant changes in mean scores at 2 weeks compared to baseline. Mean scores were significantly worse compared to baseline at 1, 2, 3, and 4 weeks postop for ASK Nasal-12 and from baseline to 1, 2, and 3 weeks post-op for the SNOT-22. The degree of correlation between scores at two and three weeks was high, suggesting good test–retest reliability (r (107) = 0.748, p < 0.001). Face validity using factor analysis suggests that the 5-factor solution (i.e., 5 subscales) proposed for SNOT-22 in chronic rhinosinusitis patients is not valid in pituitary surgery patients. The MCID as determined using the distribution method was 7.5.

Conclusions: Although SNOT-22 is acceptable as a sinonasal QOL instrument for tracking endoscopic pituitary surgery patients, shorter QOL instruments that are more sensitive to clinical change and specifically developed for this patient population such as the ASK Nasal-12 are recommended. The use of five subscales of SNOT-22 is not valid if used in this patient population.

Publication History

Article published online:
12 February 2021