Determination of the minimal important change in the quality of life in people with aphasia. A clinimetric study of the evaluation of the SAQOL-39NLg.

Abstract

Background: Aphasia influences the ability to communicate and can influence quality of life (QoL). To measure QoL in people with aphasia (PWA), the stroke and aphasia quality of life scale (SAQOL-39NLg) was developed. The SAQOL-39NLg is divided into three domains. All psychometric properties of the SAQOL-39NLg have been determined, except for the minimal important change, which indicates the experienced change in QoL according to PWA. Therefore, the interpretability of test-retest results on the SAQOL-39NLg is limited.

Aim: Determining the Minimal Important Change (MIC) in terms of clinical relevance of test-retest results on the SAQOL-39NLg, in people with chronic aphasia post stroke.

Methods and procedures: This study involved a prospective clinimetric design, in which on two points in time data of the SAQOL-39NLg in PWA (n=35) were collected by an anchor-based approach of the MIC. Participants assessed their change in QoL since the previous measurement by responding to anchor questions, using six-point Likert scales. The results of the two measurements and the anchor questions were used to calculate MIC for improvement and deterioration in QoL.

Outcomes and results: The MIC for improvement on the SAQOL-39NLg in general is 0.09 points, for the domain ‘physical’ 0.03, for ‘communication’ 0.43, and for the psychosocial domain –0.35. The MIC for deterioration on the SAQOL-39NLg in general was –¬0.22, for the domain ‘physical’ –0.21, for ‘communication’ –0.07, and for the psychosocial domain –0.22 points.

Conclusions: This study provides scores of the clinical relevance of the SAQOL-39NLg for improvement and deterioration in QoL as experienced by PWA. These scores enhance the interpretability of the SAQOL-39NLg, which could be added to the guideline of this questionnaire.