Validation of the Observer-Reported Communication Ability (ORCA) measure for individuals with Rett syndrome.

Area of Science:

• Neurodevelopmental disorders
• Communication sciences
• Psychometrics

Background:

• Rett Syndrome (RTT) is a rare neurodevelopmental disorder affecting communication abilities.
• Existing measures may not fully capture communication nuances in females with RTT.
• Caregiver-reported measures are crucial for assessing functional communication.

Purpose of the Study:

• To validate the Observer-Reported Communication Ability (ORCA) measure for assessing communication in females with Rett Syndrome (RTT).
• To ensure the ORCA measure is a reliable and valid tool for caregivers of individuals with RTT.

Main Methods:

• Qualitative interviews with 19 caregivers of individuals with RTT (ages 2+) for concept elicitation and cognitive interviewing.
• Quantitative validation study involving 279 caregivers to assess construct validity and reliability.
• Modified the ORCA measure based on qualitative feedback.

Main Results:

• The modified ORCA measure was well-understood and captured relevant communication concepts.
• Demonstrated high reliability (Cronbach's alpha = 0.90, ICC = 0.88).
• Showed strong correlation with the Communication and Symbolic Behaviors Scale (r = 0.73) and no significant floor or ceiling effects.

Conclusions:

• The modified ORCA measure is an acceptable and valid caregiver-reported tool for assessing communication ability in females with RTT.
• Supports the use of the ORCA measure in clinical and research settings for RTT.
• Further research should explore longitudinal validity and associations with clinician-based measures.