Life satisfaction questionnaire (Lisat-9): reliability and validity for patients with acquired brain injury

The aim of this study was to determine the reliability and discriminant validity of the Dutch version of the life satisfaction questionnaire (Lisat-9 DV) to assess patients with an acquired brain injury. The reliability study used a test-retest design, and the validity study used a cross-sectional design. The setting was the general rehabilitation centre. There were 159 patients over 18 years of age, with an acquired brain injury, in the chronic phase. The main outcome measures were weighted kappa of test and retest data on the nine questions of the Lisat-9 DV and significance levels of differences between subgroups of patients who are expected to differ in terms of Lisat-9 scores, on the basis of other instruments. The results were as follows: the reliability was moderate, with the weighted kappa ranging from 0.41 to 0.64. In terms of validity, subgroups of patients who were expected to differ in terms of the Lisat-9 domains did indeed differ significantly, except for the difference in the Lisat score for 'contact with friends and acquaintances' between subgroups defined by higher or lower scores on the corresponding domain of the Frenchay Activities Index. As there was a plausible explanation for not finding a significant difference between subgroups defined by one of the Frenchay Activities Index domains and significant differences were found between the subgroups defined by other instruments corresponding to the same domain, we conclude that the discriminant validity is good. The reliability was not clearly affected by cognitive disorder or aphasia. The conclusions were that the reliability of the Lisat-9 DV for patients with an acquired brain injury was moderate; the discriminant validity was good.