The Psychometric Properties of Generic Preference-Based Measures in Amyotrophic Lateral Sclerosis

Abstract

Background: Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by the loss of motor neurons. Preference-based measures (PBMs) of health-related quality of life (HRQL) can be utilized for cost-effectiveness analyses of interventions in individuals with ALS. However, current measures are generic (GPBMs) and the psychometric properties of these measures have not yet been evaluated in ALS. Purpose: The purpose of this thesis was to evaluate the psychometric properties of GPBMs in ALS by 1) conducting a systematic review of the psychometric properties of GPBMs, and 2) assessing the content and convergent validity of GPBMs in ALS. Methods: Two studies were conducted. First, a systematic review was performed, and four databases were searched to identify studies that used and reported on the psychometric properties of GPBMs in ALS. Second, participants were recruited from three clinical sites across Canada and outcome measures were administered through an online or hardcopy survey. Areas of importance to the HRQL of individuals with ALS were identified using the Patient Generated Index (PGI), mapped against GPBMs to determine their coverage and scores were compared to determine convergent validity. Results: For the first study, the EQ-5D-3L was found to be the most commonly used GPBMs in ALS. It demonstrated convergent and known-groups validity however, significant floor effects were observed. For the second study, results indicated that the majority of GPBMs identified approximately half of the areas impacted by ALS. In addition, there were several domains not identified by GPBMs. Conclusion: This thesis highlights the importance of complete psychometric evaluation of measures in ALS. There is the need for the development of an ALS specific preference-based measures that reflects the health concerns of individuals with ALS; as GPBMs used in ALS were evaluated and deemed to be lacking in support for their usage in ALS.