Development of a reliable self-report outcome measure for pragmatic trials of communication therapy following stroke: the Communication Outcome after Stroke (COAST) scale

Clin Rehabil. 2008 Dec;22(12):1083-94. doi: 10.1177/0269215508090091.


Objective: To develop and validate a clinically feasible measure of communication effectiveness for people with any type of communication problem following stroke.

Design: Cross-sectional, interview-based, psychometric study, building on the development phase for construction of the Communication Outcome after Stroke (COAST) scale.

Setting: A community sample from the northwest of England, UK.

Subjects: One hundred and two people with communication problems (aphasia and/or dysarthria) following a stroke, within the previous 4-12 months.

Interventions: Administration of the COAST scale, on two occasions, within a two-week period, and collection of demographic and other data relating to disability, degree of aphasia (where appropriate) and hospital diagnosis of aphasia/dysarthria.

Main measures: Acceptability (missing values), reliability (internal consistency and test-retest reliability) and item analysis (item redundancy).

Results: Ninety-seven (visit 1) and 98 (visit 2) respondents provided usable data for the psychometric analysis. The 29-item COAST scale showed good acceptability (few missing values, sample spread 28-100%), internal consistency and test-retest reliability for the scale (alpha = 0.95; ICC = 0.90) and its subscales (alpha = 0.65-0.93; ICC = 0.72-0.88), but possible item redundancy. A revised scale of 20 items was produced, demonstrating good internal consistency and test-retest reliability (alpha = 0.83-92; ICC = 0.72-0.88).

Conclusions: The COAST is a patient-centred, practical and reliable measure that can be used to assess self-perceived communication effectiveness for people with aphasia and/or dysarthria. Further testing on construct validity and responsiveness to change is needed before the measure can be firmly recommended for use within clinical practice and research.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adult
  • Aged
  • Communication Disorders / diagnosis*
  • Communication Disorders / etiology*
  • Cross-Sectional Studies
  • Disability Evaluation*
  • Female
  • Humans
  • Interviews as Topic
  • Male
  • Middle Aged
  • Reproducibility of Results
  • Severity of Illness Index
  • Stroke / complications*
  • Young Adult