Purpose: To translate the Trunk Impairment Scale (TIS), a measure of trunk control in patients with stroke, into Norwegian (TIS-NV), and to explore its construct validity, internal consistency, intertester and test-retest reliability.
Method:The TIS was translated according to international guidelines. 201 patients with acute stroke were recruited for the validity study, and 50 inpatients with acquired brain lesions were recruited for the study of intertester and test-retest reliability.Construct validity was analysed using explorative factor analysis, confirmatory factor analysis and item response theory, internal consistency with Cronbach's alpha test, and intertester and test-retest reliability with kappa and intraclass correlation coefficient tests.
Results:The back-translated version of TIS-NV was validated by the original developer. The subscale Static sitting balance was removed from the test. Six testlets were hierarchically constructed by combining items from the subscales Dynamic sitting balance and Coordination, and renamed modified TIS-NV (TIS-modNV). After these modifications the TIS-modNV fitted well to a locally dependent unidimensional item response theory model. The test demonstrated good construct validity, excellent internal consistency, as well as high intertester and test-retest reliability for the total score.
Conclusions:The TIS-modNV is a valid and reliable scale for use in clinical practice and research.3
Main textPatients with disability due to neurological lesions constitute one of the greatest challenges for society and health services in developed countries [1]. The most common cause of brain damage in adults is stroke, and in Norway approximately 15.000 persons suffer a stroke each year [2]. Rehabilitation should be beneficial for the individual patient as well as for society [3], and adequate assessment tools are needed to examine relevant functional aspects.Impaired balance is a common physical deficit post stroke [4;5], and improved balance has been found to be associated with improved rehabilitation outcomes [6], ability to perform daily activities [7], and walking [8]. Impaired balance increases the risk of falls [9], and may thus imply social problems and high economic costs [10].The trunk seems particularly important for balance as it stabilizes the pelvis and spinal column [11], being a prerequisite for coordinated use of the extremities in functional activities such as reaching and gait [12]. Impaired trunk control seems common post stroke [13], and trunk control assessed in patients early after stroke has been found predictive of long-term functional improvement [14;15] Even if previous studies using CTT have given important psychometric information, there are several problems with the assumptions underlying CTT such as sample dependency, item equivalence and standard error of measurement [25]. If the data can meet certain rather strict assumptions, Item Response Theory (IRT) overcomes many of these limitations [26;27]. IRT also provides rather sophisticated psyc...