Validation of the "Patient-Acceptable Symptom State" Question as Outcome Measure in AChR Myasthenia Gravis: A Multicentre, Prospective Study

Abstract

Introduction: Patient Acceptable Symptom State (PASS) is emerging as a valuable subjective measure of the overall myasthenia gravis (MG)-related burden. This study aimed at identifying PASS-positive thresholds for the most used clinical scales, investigating whether PASS and MGFA post-intervention status capture different aspects of the disease outcome, and identifying clinical variables associated with PASS=YES response.

Methods: Adult AChR-MG patients were prospectively enrolled at two Italian Centres (Rome: index cohort; Florence: validation cohort). PASS thresholds for MG-ADL, QMG, and MG-QOL15r were defined in the index cohort by ROC analysis and validated in the validation cohort; predictors of favorable PASS were identified by multivariable analysis.

Results: This study included 173 patients (44% females, median age at onset: 53 years). PASS=YES patients had significantly lower median MG-ADL, QMG, and MG-QOL15r scores, with the following thresholds for PASS=YES: MG ADL ≤ 2, QMG ≤ 8 and MG-QOL15r ≤ 6. The MG-ADL (OR = 0.46, 95% CI = 0.36-0.60, p < 0.001), QMG (OR = 0.72, 95% CI = 0.64-0.81, p < 0.001) and MG-QOL15r (OR = 0.76, 95% CI = 0.70-0.84, p < 0.001), were independently associated with a favorable PASS. The degree of ocular involvement in each scale was the strongest negative determinant of PASS=YES.

Conclusions: This study validates the PASS question and highlights the relevance of ocular complaints in patients' perception of MG burden.

Keywords: myasthenia gravis; ocular symptoms; outcome; patient‐acceptable symptom state; patient‐reported outcome measures; quality of life.