Psychometric properties of the stroke specific quality of life scale for the assessment of participation in stroke survivors using the rasch model: a preliminary study


A preliminary analysis was performed of the SS-QOL items that address the ICF participation category. For this, a methodological cross-sectional study was carried out involving 33 stroke survivors with chronic hemiparesis. The subjects were recruited from the outpatient clinic of the Physical Therapy Department of the University Nove de Julho (Brazil).

The following were the inclusion criteria: clinical diagnosis of primary or recurrent stroke with a history of more than six months and weakness and/or spasticity on the affected side of the body. The exclusion criteria were the presence of another clinical condition associated with hemiparesis caused by stroke, motor or comprehension aphasia and cognitive impairment established using the Mini-Mental State Examination with the cutoff points proposed by Bertolucci12).

All participants signed a statement of informed consent and were informed of the possibility of dropping out of the study at any time without penalty. This study received approval from the Human Research Ethics Committee of the University Nove de Julho (São Paulo, Brazil) under protocol number protocol 313.776/13.

Identification of the items of the SS-QOL that address the ICF participation component was based on a study by Silva et al.11), who found that 26 of the 49 SS-QOL items evaluated participation, spanning eight subscales (family roles, language, mobility, self-care, social roles, thinking, upper extremity function, and work/productivity). Five response options are offered for each item, with item scores ranging from 1 to 5. Thus, the minimum overall score for the questionnaire is 26 (lowest social participation), and the maximum score is 130 (highest social participation)11).

Read more  Are Plant-Based Alternatives to Meat Actually Healthier?

The volunteers were evaluated by a single examiner who had undergone training for the administration of the data collection instruments through theoretical and practical exercises. Considering the sociocultural characteristics of the sample, the participants could opt to have the questionnaires administered in interview form.

Descriptive statistics were performed for characterization of the sample and distribution of the scores. Measures of central tendency (mean) and dispersion (standard deviation) were used for quantitative variables, and frequency was used for categorical variables. Nonparametric variables were expressed as medians and interquartile ranges.

Rasch analysis allows calibration of the difficulty of items and the level of ability of individuals on a simple linear continuum at equal intervals along which each item and each individual are aligned13, 14). In the present study, the basic assumption was that individuals with a better participation capacity would achieve higher scores on all items of the SS-QOL scale, regardless of whether the tasks addressed were easy or difficult, whereas any individual is likely to achieve a higher score on items addressing easy tasks15). When all items of a test meet these expectations, the test is then fitted to a measurement model15), and those individuals with greater competence in the domain of a given function (participation, in the present case) are more likely to achieve higher scores than those with lesser competence. These principles are only applicable if the set of items measures a one-dimensional skill16).

In the present study, the analysis of the calibration of the SS-QOL items was carried out using the BIGSTEPS program. This program calculates MnSq values and associated t values, which indicate whether the relationship between an individual’s ability and item difficulty fulfill the assumptions of the model. Linacre and Wright17) suggest MnSq = 1 ± 0.3 with an associated t = ± 2 as reasonable values indicating the suitability of items.

Read more  How To Fix 3 Types Of Paint Streaks On Walls (And Avoid Them)

Test-retest reliability was assessed using the intraclass correlation coefficients (ICCs) which were interpreted as follows: less than 0.40 = poor reliability, 0.40 to 0.75 = moderate reliability, 0.75 to 0.90 = good reliability, and greater than 0.90 = excellent reliability18). In all inferential analyses, the level of significance was set to α = 0.05.


Recommended For You

About the Author: Tung Chi