An international core outcome set for primary progressive aphasia (COS-PPA): consensus-based recommendations for communication interventions across research and clinical settings

INTRODUCTION: Interventions to treat speech-language difficulties in primary progressive aphasia (PPA) often use word accuracy as a highly comparable outcome. However, there are more constructs of importance to people with PPA that have received less attention. METHODS: Following Core Outcome Set Standards for Development Recommendations (COSSTAD), this study comprised: Stage 1 – systematic review to identify measures; Stage 2 – consensus groups to identify important outcome constructs for people with PPA (n = 82) and care partners (n = 91); Stage 3 – e-Delphi consensus with 57 researchers. RESULTS: The systematic review identified 84 Outcome Measurement Instruments. Core outcome constructs identified included: (1) Participate in conversations with family and friends, (2) get words out, (3) be more fluent, (4) convey a message by any means, and (5) understand what others are saying. Researchers were unable to reach a consensus on measurement instruments. DISCUSSION: Further work is required to develop appropriate measurement instruments that address all core outcome constructs important to key stakeholders. Highlights: We introduce new symptom-led perspectives on primary progressive aphasia (PPA). The focus is on non-fluent/agrammatic (nfvPPA) and semantic (svPPA) variants. Foregrounding of early and non-verbal features of PPA and clinical trajectories is featured. We introduce a symptom-led staging scheme for PPA. We propose a prototype for a functional impairment scale, the PPA Progression Planning Aid.