Self- and surrogate-reported communication functioning in aphasia.
OBJECTIVE
To evaluate the dimensionality and measurement invariance of the aphasia communication outcome measure (ACOM), a self- and surrogate-reported measure of communicative functioning in aphasia.


METHODS
Responses to a large pool of items describing communication activities were collected from 133 community-dwelling persons with aphasia of ≥ 1 month post-onset and their associated surrogate respondents. These responses were evaluated using confirmatory and exploratory factor analysis. Chi-square difference tests of nested factor models were used to evaluate patient-surrogate measurement invariance and the equality of factor score means and variances. Association and agreement between self- and surrogate reports were examined using correlation and scatterplots of pairwise patient-surrogate differences.


RESULTS
Three single-factor scales (Talking, Comprehension, and Writing) approximating patient-surrogate measurement invariance were identified. The variance of patient-reported scores on the Talking and Writing scales was higher than surrogate-reported variances on these scales. Correlations between self- and surrogate reports were moderate-to-strong, but there were significant disagreements in a substantial number of individual cases.


CONCLUSIONS
Despite minimal bias and relatively strong association, surrogate reports of communicative functioning in aphasia are not reliable substitutes for self-reports by persons with aphasia. Furthermore, although measurement invariance is necessary for direct comparison of self- and surrogate reports, the costs of obtaining invariance in terms of scale reliability and content validity may be substantial. Development of non-invariant self- and surrogate report scales may be preferable for some applications.
Geriatric Research Education and Clinical Center, VA Pittsburgh Healthcare System, Pittsburgh, PA, USA.
Patrick J
PJ
Doyle
William D
WD
Hula
Shannon N
SN
Austermann Hula
Clement A
CA
Stone
Julie L
JL
Wambaugh
Katherine B
KB
Ross
James G
JG
Schumacher
D000368:Aged; D000369:Aged, 80 and over; D001037:Aphasia / Q000523:psychology / Q000534:rehabilitation; D015982:Bias; D017028:Caregivers / Q000523:psychology; D003142:Communication; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D057566:Self Report; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires