Asthma is a common chronic disease that affects persons of all ages. People with asthma report impacts on the physical, psychological and social domains of quality of life. Health-related quality of life (HRQoL) measures have been developed to complement traditional health measures such as prevalence, mortality and hospitalisation as indicators of the impact of disease. The inclusion of health and patient-focused measures of impact in population monitoring for asthma is important for guiding clinical management, predicting health outcomes, formulating clinical policy and assisting in the allocation of resources.
A range of HRQoL measurement instruments is available and choosing the most appropriate requires consideration of the context in which it will be implemented and the purposes of the data collection. The principal objective of this report is to develop a framework for assessing HRQoL measures and to make recommendations for measuring the impact of asthma on HRQoL in the Australian population. A number of measures have been included in Australian population surveys as indicators of HRQoL. Commonly, these have been single item measures to assess perceptions of life and health or to address specific issues such as reduced activity days. In this document, the attributes of these and other measurement instruments for HRQoL have been reviewed to assess their ability to accomplish the purposes of population monitoring, including comparing HRQoL in different diseases, monitoring HRQoL over time and allocating resources.
Single item measures are useful as low cost measures of overall health and have been widely used in population health surveys. However, they are restricted in content validity and sensitivity as measures of the impact of asthma on HRQoL and are vulnerable to measurement error. These limitations are not always overcome by large sample sizes or frequently repeated surveys, and sole reliance on such measures is not recommended for future monitoring.
The use of more valid and sensitive multi-item, multi-dimensional measurement instruments is limited by the practical and cost considerations of large surveys. Furthermore, many of these instruments were designed for individual patient management, and measure HRQoL with excessive precision for the purposes of large population monitoring studies. However, there are a number of shorter HRQoL profile measures that have been developed in recent years. These instruments measure HRQoL with adequate precision, validity and sensitivity and have lower respondent burden than the longer HRQoL profiles. The increased efficiency of these measures is an advantage for population health monitoring. In the future, other solutions to the problem may include the use of dynamic health assessments based on item response theory questionnaire batteries.