The Clinical Importance of Quality-of-Life Scores in Patients with Skull Base Tumors

Background: Health-related quality-of-life (QOL) outcomes are frequently used by clinicians, patients, and researchers for assessing the effectiveness of an intervention. Although small differences in QOL may be statistically significant, their clinical relevance has not been clarified. We aimed to determine the smallest changes in QOL scores of the anterior skull base surgery questionnaire (ASBS-Q) that could be considered clinically significant.

Methods: We assessed the QOL of 115 patients undergoing open or endoscopic skull base tumor resection. The minimal clinically important difference (MCID), defined as the smallest difference in QOL that patients perceive as beneficial and that would mandate a change in management, was calculated. A retrospective cohort (n = 79) was used to calculate MCID using the distribution-based methods (half standard deviation [SD], effect size [ES], and standard error of measurement [SEM]). A prospective cohort (n = 36) was used to calculate MCID using an anchor-based method. A population-based approach was used to assess the differences based on histology (benign vs. malignant), surgical approach (open vs. endoscopic), and postoperative period.

Results: The median MCID for the ASBS-Q was 0.4 (range, 0.34–0.42), reflecting an 8% change in QOL score. The population-based subgroup analysis showed a significant clinical difference in performance according to histological groups and postoperative period (7.9% and 13.4%, respectively). The surgical approach yielded a significant clinical difference in physical function and emotional status (9.8% and 16.4%, respectively). The MCID in the prospective cohort was 0.44 (range, 0.44–0.64), reflecting an 8.8% change in QOL score. Physical function and specific symptoms significantly changed during the early postoperative period (15% and 14%, respectively). The median change in scores was significantly different between patients reporting improvement (responders) and those reporting no change (nonresponders) in QOL (P = 0.003). A reliable change index threshold of 1.59 (33% change) revealed that 93% (14/15) of the responders had a significant improvement in QOL as opposed to only 31% (5/16) of the nonresponders (P < 0.001).

Conclusions: The MCID of the ASBS-Q is 0.4 (8%). Any change above this score can be considered as being clinically significant. Histology, postoperative period, and surgical approach have significant clinical impact on different QOL domains.