Minimal Clinically Important Difference of Vestibular Migraine Patient Assessment Tool and Handicap Inventory (VM-PATHI)

Introduction: Vestibular migraine (VM) is one of the most common causes of dizziness. The Vestibular Migraine Patient Assessment Tool and Handicap Inventory (VM-PATHI) is a patient reported outcome measure used to assess VM specific symptoms. An understanding of how changes in VM-PATHI relate to clinical improvement is critical for understanding VM-PATHI scores. Thus, the aim of this study is to calculate the minimal clinically important difference (MCID) for VM-PATHI.

Methods: A total of 53 subjects who met Barany Society criteria for VM or probable VM were included. All subjects selected were either 1) in a randomized double-blind placebo-controlled trial for galcanezumab (n = 22), 2) a mindfulness-based stress reduction course (n = 20), or 3) received routine clinical management (n = 11). All subjects completed VM-PATHI before and after intervention. A Global Rating of Change (GRoC) questionnaire was also completed following intervention. Anchor based methods, using the GRoC, were utilized to assess the MCID. The MCID was determined first by categorizing participants as either responders or non-responders. A receiver operating characteristic (ROC) curve was then utilized to estimate the MCID that produced the highest sensitivity and specificity.

Results: In total, 43 subjects were classified as responders and 10 were classified as non-responders. The mean VM-PATHI pre-treatment score minus the post-treatment score between the responders (mean = 14.05, SD 13.56) and non-responders (mean = 3.80, SD = 12.43) was statistically significant (p = 0.034). The VM-PATHI score change cutoff that best differentiated between responders and non-responders was a VM-PATHI change of 6. Thus, the MCID of VM-PATHI was defined to be a change of 6 points (sensitivity = 77%, specificity = 75%). The area under the ROC curve was 0.89, 95% CI [0.78, 0.98], which demonstrates an excellent ability for the VM-PATHI score change to discriminate between responders and non-responders.

Conclusions: Patients with VM are likely to demonstrate clinical improvement if their VM-PATHI score decreases by 6 or more.