Abstract
PURPOSE: The purpose of this study was to conduct validity and reliability testing of a novel quantitative instrument, the Symptom Intrusiveness Rating Scale (SyIRS), developed to assess health-related quality of life (HRQOL) based on individuals' perception of how symptoms associated with a chronic condition affect their quality of life. It was noted in a review of the literature that an instrument focusing on the impact of symptoms of HRQOL that can be used as a subjective assessment tool for all individuals with symptoms related to a chronic condition is currently not available.
DESIGN: Prospective observational study.
SUBJECTS AND SETTING: The sample was comprised of 50 participants experiencing pain associated with chronic wounds hospitalized in an urban 500-bed acute care hospital in the south central United States.
METHODS: Cognitive pretesting was conducted to test the construct of the SyIRS. Two experts in the field of HRQOL reviewed and scored statements on the SyIRS based on their relevance to HRQOL. Item-level content validity index (I-CVI) and scale-level content validity index average (S-CVI/Ave) were calculated to assess content validity. Internal consistency was tested using the Cronbach alpha. Test-retest reliability was obtained after administering the SyIRS twice over 2 weeks. The Pearson correlation was used to determine concurrent validity between the SyIRS and the SF-36v2 administered at the same time to confirm HRQOL as the construct on the SyIRS.
RESULTS: Cognitive pretesting indicated that participants interpreted the SyIRS instructions, statements, and response options as intended by the researchers. The SyIRS is a valid and reliable instrument with an S-CVI/Ave = 0.90, indicating the statement in the SyIRS all reflected HRQOL, Cronbach [alpha] = 0.904 indicated the instrument has good reliability based on internal consistency. Test-retest of SyIRS showed a strong positive correlation (r = 0.92, P < .005), indicating acceptable test-retest reliability. Correlation between the 2 subscales of SyIRS with SF-36v2 indicated moderate correlation on initial instrument completion (r = -0.56, P < .005, and r = -0.46, P < .001) as well as on the second completion (r = -0.55, P < .005, and r = -0.53, P < .005).
CONCLUSIONS: The SyIRS is a valid and reliable instrument to use for assessing HRQOL based on the perceptions of the impact symptoms associated with a chronic condition.