Defining the Minimal Clinically Important Difference for Patients with Vestibular Schwannoma: Are all Quality-of-Life Scores Significant?

BACKGROUND: The diagnosis of vestibular schwannomas (VS) is associated with reduced patient quality of life (QOL). Minimal clinically important difference (MCID) was introduced as the lowest improvement in a patient-reported outcome (PRO) score discerned as significant by the patient. We formerly presented an MCID for the Penn Acoustic Neuroma QOL (PANQOL) battery based on cross-sectional data from 2 tertiary referral centers. OBJECTIVE: To validate the PANQOL MCID values using prospective data. METHODS: A prospective registry capturing QOL was queried, comprising patients treated at the authors' institution and Acoustic Neuroma Association members. Anchor- A nd distribution-based techniques were utilized to determine the MCID for domain and total scores. We only included anchors with Spearman's correlation coefficient larger than 0.3 in the MCID threshold calculations. Most domains had multiple anchors with which to estimate the MCID. RESULTS: A total of 1254 patients (mean age: 57.4 yr, 65% females) were analyzed. Anchor-based methods produced a span of MCID values (median, 25th-75th percentile) for each PANQOL domain and the total score: Hearing (13.1, 13-16 points), balance (14, 14-19 points), pain (21, 20-28 points), face (25, 16-36 points), energy (16, 15-18 points), anxiety (16 [1 estimate]), general (13 [1 estimate]), and total (12.5, 10-15 points). CONCLUSION: Current findings corroborate our formerly shared experience using multi-institutional, cross-sectional information. These MCID thresholds can serve as a pertinent outcome when deciphering the clinical magnitude of VS QOL endpoints in cross-sectional and longitudinal studies.