Observer-Reported Communication Ability (ORCA) Measure

The ORCA measure captures overall communication ability through observable behaviors within expressive, receptive, and pragmatic types of communication. The measure consists of 81 total questions with 70 behavioral items within 22 concepts/functions (e.g., refuse object, make choices) that cover expressive, receptive and pragmatic areas of communication, alongside a set of 11 descriptive items that capture important information about the individual’s unique ways of communicating (e.g. modalities the individual uses, their current vocabulary, and language complexity). The questionnaire is designed to be completed by the primary caregiver who is most familiar with the individual and the ways they communicate. The descriptive items follow skip logic, so it is possible not every caregiver will complete every question.

The ORCA measure was purposely designed to be modality agnostic – meaning that a child could score high or low on the ORCA regardless of whether they use gestures/signs, vocalizations/sounds, words, and/or assistive technology to communicate. The ORCA measure is available in English and has language translations in Arabic (Israel), Dutch (Belgium), Dutch (Netherlands), English (Australia), English (Canada), English (UK), French (Belgium), French (Canadian), French (France), German (Austria), German (Belgium), German (Germany), Hebrew (Israel), Hungarian (Hungary), Italian, Japanese (Japan), Korean (South Korea), Polish (Poland), Portuguese (Portugal), and Russian (Russian Federation), Simplified Chinese (China), Spanish (Argentina), Spanish (Columbia), Spanish (Spain), Spanish (USA), and Turkish (Turkey).

The ORCA measure was developed using rigorous qualitative and quantitative methods and was originally designed to assess the communication ability of an individual with Angelman syndrome (AS) from the perspective of their caregiver. The target population was any individual with AS (of any genotype) aged 2 years old or older (including adults with AS). The content included in the ORCA measure was informed by interviews with parents of individuals with AS and by communication specialists (e.g., speech-language pathologists). Specialists treated both individuals with AS and individuals with other developmental communication disorders.

The ORCA measure was originally developed for Angelman syndrome and has also been validated in Rett syndrome. Currently, the ORCA measure is being evaluated for 12 other rare neurodevelopmental disorders, including: SYNGAP1-related intellectual disability, STXBP1-related disorders, Hunter syndrome (MPS-II), Phelan McDermid syndrome (PMS), Malan syndrome (NFIX), SCN2A-related disorders (SRD), SETBP1 haploinsufficiency disorder (SETBP1-HD), Schinzel-Giedion syndrome (SGS), HNRNPH2-related disorders, Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS), GRIN2B-related neurodevelopmental disorder, and Hao-Fountain Syndrome (USP7). The ORCA measure may be applicable to other similar neurodevelopmental disorders. Ideally, these should be populations where most individuals are nonverbal or communicate primarily through modalities other than spoken words. Please note, if you would like to use the ORCA measure with populations other than Angelman syndrome or Rett syndrome, then the ORCA measure would be considered an exploratory measure and could not serve as the primary outcome measure until additional validity evidence is gathered in your population and context of use. Please click here for more information and guidance.

The scoring approach for the ORCA measure is different from many other clinical outcome assessments by design, and reflects the unique complexities of communication ability. Thus, the ORCA measure cannot be scored by hand, and an accompanying SAS macro must be used. R can also be used to run the macro. For researchers who do not have the ability to use SAS or R statistical software programs, a free scoring feature is available through the Greenlight platform. If you are interested in using this feature, please refer to the ORCA measure Scoring for more information.

Download these ORCA resources for more information:

• FAQ

• ORCA measure Scoring Manual

Accepted Publications:

• Reeve, B.B., Lin, L., Rader, A. et al. “Evaluating different scoring algorithms to assess communication ability for individuals living with Angelman syndrome: the Observer-Reported Communication Ability (ORCA) measure.” J Patient Rep Outcomes, (2026). https://doi.org/10.1186/s41687-026-01072-7
• Rader, A., Lin, Li., Sadhwani, A., Lucas, N., Jones, HN., et al. “Caregiver Meaningful Score Differences and Meaningful Score Regions for the Observer-Reported Communication Ability Measure for Individuals with Angelman Syndrome.” Value in Health, (2026). https://doi.org/10.1016/j.jval.2026.02.002
• Rader, A., Lin, L., Jones, H.N. et al. “Association of the Observer-Reported Communication Ability (ORCA) Measure with Established Communication Measures: Insights From the Angelman Syndrome Natural History Study”. J Autism Dev Disord (2026). https://doi.org/10.1007/s10803-026-07224-4
• Zigler, Christina K et al. “The spectrum of communication abilities in children with 12 rare neurodevelopmental disorders: a qualitative study with caregivers.” The Journal of Child Psychology and Psychiatry, https://doi.org/10.1111/jcpp.70063
• Chen, D., Zigler, C.K., Lin, L. et al. ‘Understanding reliability of the observer-reported communication ability measure within Angelman syndrome through the lens of generalizability theory.’ J Patient Rep Outcomes 8, 50 (2024), https://doi.org/10.1186/s41687-024-00725-9
• Reeve, Bryce B., et al. ‘Validation of the Observer-Reported Communication Ability (ORCA) Measure for Individuals with Rett Syndrome’. European Journal of Paediatric Neurology, Elsevier, https://doi.org/10.1016/j.ejpn.2023.07.007
• Zigler, Christina K., et al. ‘Exploring Communication Ability in Individuals With Angelman Syndrome: Findings From Qualitative Interviews With Caregivers’. American Journal on Intellectual and Developmental Disabilities, vol. 128, no. 3, Apr. 2023, pp. 185–203, https://doi.org/10.1352/1944-7558-128.3.185
• Zigler, Christina K et al. “Validation of the Observer-Reported Communication Ability (ORCA) Measure for Individuals With Angelman Syndrome.” American journal on intellectual and developmental disabilities vol. 128,3 (2023): 204-218. doi:10.1352/1944-7558-128.3.204