CORRESPONDENCE

Re: A Structured Review of Studies on Health-Related Quality of Life and Economic Evaluation in Pediatric Acute Lymphoblastic Leukemia

Elise Davis, Elizabeth Waters

Affiliation of authors: School of Health and Social Development, Deakin University, Burwood, Victoria, Australia

Correspondence to: Elise Davis, PhD, School of Health and Social Development, Faculty of Health and Behavioural Sciences, Deakin University, Melbourne Campus, 221 Burwood Hwy., Burwood, 3125 Victoria, Australia (e-mail: elise.davis{at}deakin.edu.au).

Dramatic improvements in survival rates for children with cancer have resulted in increasing recognition and interest in pediatric quality of life (QOL) and health-related QOL (HRQOL). A recent review of pediatric HRQOL instruments for oncology patients published in the Journal of the National Cancer Institute Monographs identified 16 QOL/HRQOL instruments for children with cancer (1). Although Pickard et al.'s (1) review provides extremely useful information about the basic properties of the instruments (e.g., subjective dimensions of health status or domains, number of items), it is important to highlight the impact of including particular domains and items on the QOL scores for children with cancer.

Domains measuring disease-related symptoms and physical, social, cognitive, and emotional function that are included in QOL/HRQOL instruments vary; consequently, we have concerns about what dimensions are included to measure HRQOL/QOL. QOL and HRQOL are in fact different constructs. QOL is usually described as an overall assessment of well-being across various domains (2). Whereas QOL encompass all aspects of an individual's life (housing, neighborhood, and school), HRQOL only refers to aspects of health.

In both QOL and HRQOL instruments for children with cancer, many of the domains refer to problems or limitations, such as somatic distress, physical restriction, discomfort from medical treatment, and pain, rather than to well-being or positive health. These domains are based on the assumption that the absence of problems (physical, social, or emotional) equals the presence of well-being. Although this underlying assumption has not been well studied in children, Hagerty et al. propose that negative domains should not be included in QOL instruments (3). This is because the optimal effect of negative domains, such as the absence of pain or somatic distress, can only have a neutral effect on QOL, not a positive effect (3).

A further concern with the domains is that many HRQOL instruments measure functioning (e.g., physical functioning, mobility, sensation, self-care, cognitive functioning, and social functioning). For example, the Pediatric Oncology QOL Scale (4) includes items such as "My child has had nausea or vomiting due to treatment" and the Pediatric Cancer Quality of Life Inventory-32 includes items such as "it is hard for me to run" and "I have trouble solving math problems" (5).

Functioning refers to whether a child can perform daily activities (6). Although it is important to measure a child's functioning, it is not the same as QOL and may best be assessed with an instrument designed to measure functioning. QOL/HRQOL refers to a child's (self-report or parent proxy) perceptions of his or her health and life. There is no evidence to suggest that a child's perception of his or her life corresponds with the ability to perform various tasks/activities. It is possible that some children may have poor functioning yet have a high HRQOL/QOL if they have adapted to their current health state or if they have not experienced a healthier state (7).

In summary, we recommend that existing instruments be critically appraised to ensure that they measure well-being, not just ill-being and poor functioning. Such an appraisal is necessary if the field is to progress beyond instrument development and testing to the planning and empirical testing of programs and interventions to increase QOL.

REFERENCES

(1) Pickard AS, Topfer L, Feeny DH. A structured review of studies on health-related quality of life and economic evaluation in pediatric acute lymphoblastic leukemia. J Natl Cancer Inst Monogr 2004;33:102–25.[Medline]

(2) Bjornson KF, McLaughlin JF. The measurement of health-related quality of life (HRQOL) in children with cerebral palsy. Eur J Neurol 2001;8 Suppl 5:183–93.[CrossRef][ISI][Medline]

(3) Hagerty M, Cummins R, Ferriss A, Land K, Michalos A, Peterson M, et al. Quality of life indexes for national policy: review and agenda for research. Soc Indic Res 2001;55:1–96.[CrossRef][ISI]

(4) Goodwin DA, Boggs SR, Graham-Pole J. Development and validation of the Pediatric Oncology Quality of Life Scale. Psychol Assess 1994;6:321–8.[CrossRef]

(5) Varni JW, Katz ER, Seid M, Quiggins DJ, Friedman-Bender A. The Pediatric Cancer Quality of Life Inventory-32 (PCQL-32). I. Reliability and validity. Cancer 1998;82:1184–96.[CrossRef][ISI][Medline]

(6) Drotar D. Validating measures of pediatric health status, functional status, and health related quality of life: key methodological challenges and strategies. Ambul Pediatr 2004;4(4 Suppl):358–64.[CrossRef][ISI][Medline]

(7) Vitale MG, Levy DE, Moskowitz AJ, Gelijns AC, Spellmann M, Verdisco L, et al. Capturing quality of life in pediatric orthopaedics: two recent measures compared. J Pediatr Orthop 2001;21:629–35.[CrossRef][ISI][Medline]



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