The Asthma Quality of Life Questionnaire

Project Name

The use of the Asthma Quality of Life Questionnaire (AQLQ) to derive QALYs

Project overview

There are studies of asthma that include the condition specific instrument AQLQ, but no generic preference based measure. Usually, this means QALY information cannot be derived from these studies. However, there are two ways to make this possible.

One is by "mapping" the AQLQ onto some existing generic preference based measure, such as the EQ-5D or SF-6D. Based on an external, independent dataset where both AQLQ and EQ-5D (say) were administered, a series of regression analyses are carried out to estimate the best mapping relationship between the two instruments.

The other is to conduct a "valuation study" of the AQLQ. Since the existing AQLQ instrument has too many items and too many levels for a valuation study, the instrument is first reduced to a more manageable size. Then, selected states are valued using TTO, and the results modelled using regression techniques, to estimate the values associated with all other states that were not directly valued.

Relevant Publications

  • Tsuchiya A, Brazier J, McColl E, Parkin D. Deriving preference-based single indices from non-preference based condition-specific instruments: Converting AQLQ into EQ5D indices, Sheffield Health Economics Group Discussion Paper (2002) [download]
  • Young T, Yang Y, Brazier J, Tsuchiya A, Using Rasch analysis to aid the construction of preference based measures from existing quality of life instruments, Health Economists' Study Group Meeting, Summer 2005