Evaluating Health Utilities in Adolescents: Raising the Profile of an Alternative Method for Assessing Health-Related Quality of Life
Article Outline
Abbreviations: HRQOL, Health-related quality of life, IBD, Inflammatory bowel disease, PCDAI, Pediatric Crohn's Disease Activity Index, QALY, Quality-adjusted life-years, SG, Standard gamble, TTO, Time to trade-off
In this issue of The Journal, Yi et al1 report on their work examining health utilities in a cohort of adolescents with chronic inflammatory bowel disease (IBD) compared with healthy controls. This work is important because it helps raise the profile of a topic that has been relatively understudied in pediatrics. Although the past several decades have seen an exponential increase in interest in the study of health-related quality of life (HRQOL) in pediatrics, this interest has been skewed to health status as opposed to health value assessment.
See related article, p 527
Health status versus health values—what is the difference? As discussed in this article, these are 2 fundamentally different approaches to the evaluation of HRQOL.2, 3 Most HRQOL work in pediatrics has concentrated on creating age- and developmentally appropriate tools to evaluate the health status of children and adolescents.4, 5, 6 Through health status assessment, one seeks to describe an individual's functioning in 1 or more domains (eg, social, physical, emotional). Tackling HRQOL in a different way, health utility measures (also known as health value or health preference measures) assess the value—or desirability—of a state of health to represent health on a metric scale, usually between 1 (full health) and 0 (death).7 The standard gamble (SG) and time to trade-off (TTO) are among the most commonly used health utility measures. The standard gamble assesses the risk of death that an individual would be willing to incur to improve a state of health.7 The time to trade-off approach asks how many days, months, or years of life an individual is willing to give up in exchange for a better state of health.7
These authors have previous experience in evaluating health utilities in adolescents, having conducted a similar study in patients with cystic fibrosis.8 In the present study, however, the authors not only sought to examine the feasibility of ascertaining health value scores in adolescents with IBD and healthy controls, but also explored potential predictors of these health value scores. In 67 patients with IBD (age 11 to 19 years) and 88 healthy controls, they noted no major feasibility concerns. Using a battery of validated measures, evaluating personal, family, and social characteristics, the authors found lower TTO scores in the patients with IBD than in healthy adolescent controls, but no significant difference in SG scores different between the 2 groups. Of the multiple factors studied, poorer emotional functioning and spiritual well being were associated with lower TTO and SG scores. But in both cases, the amount of variability explained in the scores by emotional functioning and spiritual well being was not large (17% for TTO scores; 22% for SG scores).
The authors studied other potential predictors but did not find any other significant ones in a multivariate analysis of this population. The inability to delineate factors that better explain the variability of health value scores may be because the factors that are truly important have not yet been explored or identified. Another possible explanation may be that the tools used to assess the factors may be faulty. For instance, the tool used in this study to assess disease activity, the modified Lloyd-Still Index,9 is no longer routinely selected as a measure for evaluating disease activity in children with IBD. Rather, the Pediatric Crohn's Disease Activity Index (PCDAI) is the measure more commonly selected, given its demonstrated reliability and validity in pediatric Crohn's disease.10 At the time that the authors began this study, there was no single accepted disease activity measure for pediatric ulcerative colitis, but this is no longer the case, now that the Pediatric Ulcerative Colitis Activity Index has been published.11 No matter which measure of disease activity is selected, a potential limitation still may be that the measure only captures the current activity of the IBD and does not provide a clear picture of disease activity pattern over time.
Leaving aside the question of the validity of the Lloyd-Still Index for assessing disease activity, because it included few patients with severe disease, this study may have been insufficiently powered to detect the impact of disease activity and disease severity on health value scoring. Although the authors conclude that efforts should be made to address the spiritual and emotional health needs of patients, further study is needed to evaluate the potential impact of an individual's life experience with the disease and its management and the potential influence of this on the scoring of health utilities.
The authors are to be commended for their work in the study of health utilities in adolescents. Additional research is needed to better understand how to best interpret and report health utilities in adolescents, as well as in younger children. Most work in health utilities done to date has been conducted in adults. Even though work has been done on evaluating the age at which the various HRQOL tools can be used,12 the impact of chronological age and changing neurodevelopmental status on how adolescents express their preference for a certain health state remains unclear. One indicator of an adult level of cognitive development is the ability to understand future consequences of actions. For many, this developmental stage is not reached until late adolescence. Risk-taking behaviors and a sense of invulnerability are other adolescent traits that could affect an individual's health state preferences.
Why is it important to include assessment of health utilities in pediatrics? Besides their use as global HRQOL measures in clinical trials, they also can be used to incorporate the perspective of a patient's personal value system in individual decision making regarding diagnostic testing and treatment considerations.7 In addition, health utilities are used as quality weights for calculating quality-adjusted life-years (QALYs).13 A QALY is the patient's preference for 1 year of life at a decreased state of health compared with life at an optimal state of health. QALYs are important tools in decision and cost-effectiveness analyses, because they incorporate both quality and quantity of life in a single metric, to determine the mathematical product of life expectancy and QOL of remaining life-years.2
The pediatric patient population with IBD evaluated in this study provides an excellent example of why having the ability to evaluate an individual's health preferences can be relevant. Increasingly we are seeing the emergence of effective, but costly, therapies for managing chronic illnesses like IBD. Because there is no cure for IBD, and no major difference in overall life expectancy from the healthy population, adolescents diagnosed with IBD will live with the disease for many years. The cost of biological therapy can exceed $20 000/year. For those individuals started on such therapies, at least in 2008, there is no clear exit strategy, so we may be committing these patients to costly interventions for the long-term. With more and more of these therapies becoming available, and with increasing concerns about sustainability of the health care system in its current form, the ability of both health care providers and payers to demonstrate the cost-effectiveness of proposed options for therapy will become increasingly important.
References
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PII: S0022-3476(08)01047-0
doi:10.1016/j.jpeds.2008.11.039
© 2009 Mosby, Inc. All rights reserved.
Refers to article:
- Health Values in Adolescents with or without Inflammatory Bowel Disease , 25 November 2008
