A Patient-Reported Outcome Measure of Communication Difficulties in Friedreich Ataxia: COMATAX

Friedreich ataxia (FA) causes progressive impairment of communication due to gradual deterioration of speech, associated with impaired hearing, socio-cognitive and language skills. There is an urgent need to investigate the impact of this multiparametric alteration on patients' lives. Therefore, the COMunication and ATAXia measure (COMATAX) was developed and validated in French and German.

In the PROFA study (NCT05943002), we conducted focus groups and cognitive interviews with patients with FA, professionals and caregivers to elaborate relevant items of communication disabilities. Subsequently, the measure was validated in 93 patients with FA via a mobile health app. For validation, distribution properties, reliability (Cronbach's alpha) and validity (correlations with VHI-30, SSQ-12, SARA total score, SARA speech item, Speech rate and GAA repeats; known-groups validity by age, sex, and self-rated health/wellbeing, disease-severity, hearing function, daily activities, and exploratory factor analysis) were calculated. An IRT analysis was performed to assess item characteristics.

COMATAX consists of 17 items (five response options each) and an 18th question asking about the most bothersome symptom. We observed high internal consistency for the total COMATAX scale (α = 0.897), strong correlations with VHI-30 (r=.894), SSQ-12 (r = -.531), moderate with SARA score (r=.498), SARA speech item (r=.416), Speech rate (r=-.354), weak with GAA repeat length (r_GAA1=-0.207) and the ability to distinguish between different subgroups (disease severity, self-rated health, wellbeing, hearing function, and daily activities). Most items showed good discrimination of communication ability.

The COMATAX is a valid and reliable patient-reported communication disability measure, useful in future therapeutic trials in FA.