Defining the Minimally Clinically Important Difference for Patients with Vestibular Schwannoma

Background Vestibular schwannomas (VS), the most common neoplasms of the cerebellopontine angle, have the potential to cause significant reduction in patient's quality of life (QOL). The concept of minimum clinically important difference (MCID) has been put forth as the smallest amount of change in a patient-reported outcome (PRO) score perceived as important by the patient. We have previously published our experience with 538 patients who were cross-sectionally surveyed at a mean follow-up of 7.7 years after treatment. Herein, we sought to determine the MCID values for the Penn Acoustic Neuroma QOL (PANQOL) instrument using 12-month prospectively collected data.

Methods We queried the results of a prospective study assessing quality of life, composed of patients evaluated at the authors' center and members of the Acoustic Neuroma Association. PANQOL is a 26-item instrument divided into seven domains related to patient's hearing, balance, head pain, facial weakness, depression, level of energy, and general well-being. Anchor-based (seven different anchors) and distribution-based (half a standard deviation) methods were used to calculate the MCID for domain and total scores. Only anchors with a correlation coefficient greater than 0.3 were considered suitable for the MCID threshold calculations. Patients with neurofibromatosis type 2 and those who received more than one treatment were excluded from the analysis.

Results A total of 782 patients (mean age: 58 years, 69% females) with complete 12-month PRO data were analyzed. One hundred fifty-seven patients were managed with observation alone, 174 patients had radiosurgery, while 451 patients underwent microsurgical resection. Distribution- and anchor-based techniques generated a range of MCID values (median, range) for each domain and the total score: hearing (12, 10–13 points), balance (14, 9–15 points), pain (16, 10–18 points), face (18, 13–22 points), energy (13, 7–16 points), anxiety (14, 14–19 points), general (11, 6–13 points), and total (11, 7–14 points).

Conclusion The findings of the present study validate our previously published experience using cross-sectional data. These data may serve as an appropriate endpoint when interpreting the clinical significance of VS QOL outcome studies.