Revisiting the meaning and the source of health-related constructs and their applications in neurodisability.

The aim of this review is to revisit the meaning of common concepts and frameworks promoted to capture subjective outcomes of patients, the content of their corresponding measurements, and the preferred sources of the information of interest. This is important because conceptualizations of 'health' and the subject evaluations thereof continue to evolve. Related but distinct concepts like quality of life (QoL), health-related QoL (HRQoL), functional status, health status, and well-being are often used indiscriminately to assess clinical impacts of interventions and to influence decisions about patient care and policymaking. The discussion addresses and illustrates the following issues: (1) the required features of effective and valid health-related concepts; (2) understanding underlying factors that often create confusion about QoL and HRQoL; and (3) how these concepts provide insight into, and promote, health in the context of populations with neurodisability. The hope is to illustrate how a combination of a clear research question, a hypothesis, conceptualization of the required outcomes, and operational definitions of the domains and items of interest, including item mapping, can help to achieve robust methodology and valid findings beyond the required psychometric properties.