Psychometric evaluation of the Stroke Impact Scale 3.0.
BACKGROUND
The Stroke Impact Scale 3.0 (SIS 3.0) is widely used to measure quality of life in stroke survivors; however, previous studies have not tested the original 8-factor structure of the scale. In addition, previous studies have shown floor and ceiling effect and weak reliability within the scale.


OBJECTIVE
The aim of this study was to evaluate the psychometric characteristics of the SIS 3.0, including its construct validity (factorial structure, concurrent and contrasting group validity), floor and ceiling effect, and reliability.


METHODS
A cross-sectional design was used to study 392 stroke survivors enrolled in 16 rehabilitation facilities across Italy. Factorial structure of the SIS 3.0 was tested with confirmatory factor analysis. Concurrent and contrasting group validities were evaluated with other scales measuring functional capacities, neurological functions, cognition, anxiety, depression, and generic quality of life. Floor and ceiling effects were evaluated by determining the percentages of patients with the minimum and the maximum score at SIS 3.0. Reliability was determined by Cronbach's α and test-retest.


RESULTS
Participants were 71 years old on average (SD, 11 years); 55% were men. Confirmatory factor analysis revealed a new 4-factor structure that fitted the data better than the original 8-factor structure did. Concurrent and contrasting group validity of the new 4-factor structure was supportive and no floor and ceiling effects were found. Internal consistency and test-retest reliability ranged between 0.79 and 0.98.


CONCLUSIONS
The new factorial structure of the SIS 3.0 with 4 factors showed better psychometric properties than the original 8-factor structure did. This evidence supports further use of the SIS 3.0 in clinical practice and research.
Ercole Vellone, RN, MSN PhD Student, Research Fellow, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy. Serenella Savini, RN, MSN PhD Student, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy. Roberta Fida, PhD Assistant Professor, Department of Psychology, Sapienza University, Rome, Italy. Victoria Vaughan Dickson, PhD, RN Assistant Professor, College of Nursing, New York University. Gail D'Eramo Melkus, EdD, C-NP, FAAN Florence and William Downs Professor in Nursing Research, College of Nursing, New York University. Francisco Javier Carod-Artal, MD, PhD Visiting Professor of Neurology, Medicine and Health Sciences Faculty, Universitat Internacional de Catalunya (UIC), Barcelona, Spain, and Consultant Neurologist, Department of Neurology, Raigmore Hospital, Inverness, United Kingdom. Gennaro Rocco, RN, MSN Director, Center of Excellence for Nursing Scholarship, Rome, Italy. Rosaria Alvaro, RN, MSN Associate Professor, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy.
Ercole
E
Vellone
Serenella
S
Savini
Roberta
R
Fida
Victoria Vaughan
VV
Dickson
Gail D'Eramo
GD
Melkus
Francisco Javier
FJ
Carod-Artal
Gennaro
G
Rocco
Rosaria
R
Alvaro
D000368:Aged; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D020521:Stroke / Q000523:psychology*; D000071939:Stroke Rehabilitation; D011795:Surveys and Questionnaires; D017741:Survivors