The Minimal Clinically Important Difference in Vestibular Schwannoma Quality-of-Life Assessment: An Important Step beyond P <.05

Objective. Several studies have demonstrated small but statistically significant differences in quality-of-life (QOL) scores among vestibular schwannoma (VS) treatment modalities. However, does a several-point difference on a 100-point scale really matter? The minimal clinically important difference (MCID)∗defined as the smallest difference in scores that patients perceive as important and that could lead to a change in management-was developed to answer this important question. While the MCID has been determined for QOL measures used in other diseases, it remains undefined in the VS literature. Study Design. Distribution- and anchor-based techniques were utilized to define the MCID for the Penn Acoustic Neuroma Quality of Life (PANQOL) and 36-Item Short Form Health Survey (SF-36). Setting. Two academic referral centers. Patients. Patients with VS (N = 538). Intervention. Cross-sectional postal survey. Main Outcome Measures. MCID for PANQOL domains and total score and SF-36 Physical and Mental Health Component Summary scores. Results. The MCID (median, interquartile range) for the PANQOL total score was 11 points (10-12); the MCIDs for individual domains were as follows: hearing, 6 (5-8); balance, 16 (14-19); facial, 10 (no interquartile range); pain, 11 (10- 13); energy, 13 (10-17); anxiety, 11 (5-22); and general, 15 (11-19). The MCID was 7 points (6-11) for the SF-36 Mental Health Component Summary score and 8 points (6- 10) for the Physical Health Component Summary score. Conclusions. The MCIDs determined in the current study generally exceed differences reported in previous prospective studies, in which conclusions about QOL benefit (or harm) among VS treatment modalities were based on statistical significance alone. Moving forward, these MCIDs should be considered when interpreting results of VS QOL studies.