Development of a Preference Weighting System for the Parent-Proxy Child Chronic Cough Quality-of-Life Instrument

Objectives
Cough in children is the most common reason for seeking healthcare in Australia. When chronic, it is associated with decreased quality-of-life in parents/carers and significant societal costs. Despite this, the spillover effect of chronic cough on parents/carers is seldom accounted for in economic evaluations of interventions. We aimed to develop a new method of estimating spillover health utility in this population in Australia.

Methods
We conducted a discrete choice experiment on hypothetical health states based on the Parent-Proxy Child Cough Quality of Life questionnaire. These were analyzed using a garbage-class multinomial logit model (GCL). We also obtained visual analog scale scores for 6 health states and mapped them to the latent discrete choice experiment utilities, rescaling them to the 0 to 1 health utility scale required to estimate quality-adjusted life-years.

Results
A total of 550 participants broadly representative of Australian parents completed our survey. Parental concerns about their child being able to lead a normal life had the largest coefficients in the GCL. The resulting scoring algorithm had a minimum score of.21, and a maximum of 1 (full health).

Conclusions
We have developed a new method of estimating spillover health utility values in parents of children with chronic cough in Australia. This study is also a use case for the application of GCL in extracting respondent nontrading behavior, which may cause inaccurate preference estimates, and a visual analog scale based anchoring methodological approach that could be iterated in further research. We have developed an R package and shiny app to allow the easy estimation of spillover utility scores from Parent-Proxy Child Cough Quality of Life questionnaire responses.