Reliability and telephone validity of the Stroke-specific Quality of Life (SS-QOL) scale
Background/Purpose: The SS-QOL is a validated 49-item stroke-specific quality of life scale. Scale stability over time, between raters and with different administration modes are necessary for use in large studies. The purpose of this study is to examine SS-QOL test-retest (TR) and inter-rater reliability (IR), and validity of telephone (PH) administration. Methods: Ischemic stroke survivors with no significant language or cognitive impairments were recruited as part of an ongoing study of SS-QOL version 2.0. In the TR study (N=47), a trained interviewer re-administered the SS-QOL within 2 hours of the initial interview. In the IR study (N=24), a second trained interviewer re-administered the SS-QOL within 2 hours of the first interview. The PH interview (N=34) was conducted within 48 hours of a face to face interview. Pearson correlations were used to assess the relationship between the overall SS-QOL scores and individual domain scores. Because scores may be highly correlated yet biased, paired t-tests were used to assess response bias. Overall SS-QOL score and domain scores range from 1.0 (worst) to 5.0 (best). Domains are: Mobility, Upper Extremities, Work, Self-care, Energy, Family Roles, Vision, Language, Social Roles, Cognition, Personality, and Mood. Results: 98–100% of the 3 samples were male, 88–94% were white and mean age was 66–67 years. Mean time since stroke was 4 months in the TR and IR samples and 5 months in the PH sample. SS-QOL scores were highly correlated and unbiased on TR (r=.92), IR (r=.92), and PH (r=.93) testing. All individual domain scores were also highly correlated in IR, TR and PH testing. Cognition and Personality domain scores were slightly higher on re-test and the Language domain score was slightly higher on PH administration. These differences were all < 1/4 of a standard deviation in domain score. Conclusions: The SS-QOL has excellent test-retest and inter-rater reliability. Telephone administration of the SS-QOL is accurate and unbiased. Individual domain scores are also highly reliable and observed differences in domain scores are rare and small. Validation of SS-QOL mail administration is ongoing.