Sato, A. F., Davies, W. H., Berlin, K. S., Hainsworth, K., & Weisman, S. J. (2009, April).
Measuring global impairment in pediatric chronic pain: Examining the overlap between
functional disability and health-related quality of life. Paper presented to the 2009 Midwest
Conference on Pediatric Psychology in Kansas City, MO.
Title
Measuring Global Impairment in Pediatric Chronic Pain: Examining the Overlap Between
Functional Disability and Health-Related Quality of Life
Authors and Affiliations
Amy F. Sato, M.S., University of Wisconsin – Milwaukee
W. Hobart Davies, Ph.D., University of Wisconsin – Milwaukee, Children’s Hospital of
Wisconsin
Kristoffer S. Berlin, Ph.D., Bradley Hasbro Children’s Research Center, Brown Medical School
Keri Hainsworth, Ph.D., Medical College of Wisconsin
Steven J. Weisman, M.D., Medical College of Wisconsin, Children’s Hospital of Wisconsin
Corresponding Author
Amy Sato, M.S.
Mailing Address:
Attention Amy Sato
Rhode Island Hospital
Child and Adolescent Psychiatry
Bradley Hasbro Children's Research Center
1 Hoppin St., Suite 204, Coro West
Providence, RI 02903
Email Address:
asato@lifespan.org
Consideration
Please consider this submission for either a paper or poster session.
Purpose/Background:
Research examining functional outcomes in pediatric chronic pain has typically focused on
health-related quality of life (HRQoL) or functional disability. Although the terminology (e.g.,
functional status, HRQoL) has often been used interchangeably (Varni et al., 2002) and there is
conceptual overlap between these constructs, researchers have not yet adopted a statistical
approach to clarify the relationships between these constructs. This study sought to determine
through the use of structural equation modeling (SEM) whether functional disability and HRQoL
are indicators of a broader “Global Impairment” latent construct. In addition, this study sought to
determine whether commonly used clinical indictors of pain hold together as a broader “Pain”
latent variable.
Methods:
Participants were 291 children and adolescents with chronic pain presenting to a tertiary chronic
pain clinic. Youth were 8 - 17 years old (M = 13.3, SD = 2.7), primarily female (72.2% female)
and primarily Caucasian (80.4%). Over half (52.7%) of patients reported pain duration greater
than 1 year. On a 0-to-10 numerical rating scale, participants’ best, worst, and usual pain ratings
were 1.7 (SD = 2.4), 8.7 (SD = 1.7), and 5.9 (SD = 2.1). As part of a comprehensive evaluation
prior to the establishment of a treatment plan, participants completed a demographics and
medical history questionnaire and measures of HRQoL, functional disability, and social
consequences of pain. The Pediatric Quality of Life InventoryTM Version 4.0 (PedsQL) Generic
Core Scales (Varni et al., 2001) assessed children’s perceptions of their HRQoL in the domains
of physical, emotional, social, and school functioning. The Functional Disability Inventory (FDI;
Claar & Walker, 2006; Walker & Greene, 1991) provided a unidimensional measure of
children’s perceived difficulty in physical and psychosocial functioning due to their physical
health. Internal consistencies of the FDI and PedsQL ranged from .86 to .91.
Results:
A measurement model containing the hypothesized Pain and Global Impairment latent variables
was constructed using LISREL 8.54. Because the measurement model was constructed as part of
a larger study exploring the relationships between pain, social consequences, child age/gender
and functioning, indices of social consequences and child demographics were also included.
In the initial measurement model, indictors of Global Impairment were the PedsQL and FDI total
scores and indicators of Pain were pain duration and best, worst and usual intensity. Due to
model non-convergence, the Global Impairment and Pain latent variables were re-specified (i.e.,
duration was removed from Pain and a more fine-grained approach was used for Global
Impairment). Model fit statistics were evaluated. The CFI (.90), SRMR (.06), and RMSEA (.09)
indicated adequate model fit, whereas the NNFI (.80) and SB-χ2/df (2.97) did not. All indicators
of Global Impairment and Pain loaded in the expected direction.
Conclusions:
Functional disability and HRQoL can be conceptualized as arising from a broader Global
Impairment latent construct. Pain duration emerged as distinct from other clinical indicators of
pain intensity. Given that functional disability and HRQoL appear to be tapping the same
underlying construct, it may not be necessary to administer measures of both in a busy clinical
setting.
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