Testing the integration of ICF and behavioral models of disability in orthopedic patients: Replication and extension.

Abstract

Objective: Disability from chronic illness is a major problem for society, yet the study of its determinants lacks an overall theoretical paradigm. Johnston (1996) has proposed conceptualizing disability as behavior and integrating biomedical and behavioral predictors. Dixon, Johnston, Rowley, and Pollard (2008) tested a model including constructs from the International Classification of Functioning, Disability and Health (ICF) and the theory of planned behavior (TPB) using structural equation modeling; it fitted better and explained more variance than the ICF or TPB alone. We replicated their study with a new sample from the same population (orthopedic patients awaiting joint replacement) and also tested the model after the patients had surgery. Methods: Two weeks before surgery, 342 orthopedic patients who had joint pain (most with arthritis) completed a questionnaire, with 228 completing it again 1 year after surgery. The authors tested Dixon et al.'s best-fit models cross-sectionally (before and after surgery) and assessed the goodness of fit of these imposed models to our data using structural equation modeling. Results: Findings strongly supported those of Dixon et al. Before surgery, results were very similar to Dixon et al. with all models accounting for significant variance and fitting well, but the integrated model fitted better and accounted for more variance. One year after surgery, Dixon et al.'s models showed even stronger fit to the data. Conclusions: Although behavioral and biomedical (ICF) models were supported, the integrated model provided a better explanation of disability in this population than either of these models alone and suggests biopsychosocial interventions to reduce disability.

Discriminant content validity: A quantitative methodology for assessing content of theory‐based measures, with illustrative applications

“…Pollard et al (2009) identified pure measures of ICF constructs, uncontaminated by the other constructs in the model, making it possible to test theoretical models of the relationships between constructs in the ICF and to test theoretical models that integrate the ICF with psychological models (Dixon, Johnston, Elliott, & Hannaford, 2011;Dixon, Johnston, Rowley, & Pollard, 2008;Quinn et al, 2012). Pollard et al (2009) identified pure measures of ICF constructs, uncontaminated by the other constructs in the model, making it possible to test theoretical models of the relationships between constructs in the ICF and to test theoretical models that integrate the ICF with psychological models (Dixon, Johnston, Elliott, & Hannaford, 2011;Dixon, Johnston, Rowley, & Pollard, 2008;Quinn et al, 2012).…”

Developing an integrated biomedical and behavioural theory of functioning and disability: adding models of behaviour to the ICF framework

“…Impairment (joint pain) and self-efficacy were predictive whereas OE did not predict walking limitations either in the SCT or the integrated model (Dixon, 2006). In the replication study, SCT accounted for 60% and the integrated model 64 % of variance in AL (Quinn et al, 2012). Following joint replacement surgery, the SCT explained 79% variance and the integrated model 82% variance in AL.…”

“…In each of these studies, measures of A and AL were selected on the basis of empirical work using Discriminant Content Validity methods ( Pollard et al, 2006;Pollard et al, 2009) to ensure satisfactory operationalization of these (Quinn , Johnston, Dixon, Johnston, Pollard, 2012). Table 1 about here While these findings offer considerable support for an integrated model, they are confined to one population, health condition and level of impairment and disability.…”

“…Table 1 about here While these findings offer considerable support for an integrated model, they are confined to one population, health condition and level of impairment and disability. However, we repeated the tests of the models on the same cohort following joint replacement surgery so that the health condition had now altered (Quinn et al, 2012). Participants no longer retained the arthritic joint, i.e.…”

Using impairment and cognitions to predict walking in osteoarthritis: A series of n‐of‐1 studies with an individually tailored, data‐driven intervention

“…To date, the integrated model has been tested using group-based designs identifying differences in activity limitations and walking between individuals with disabling chronic conditions including osteoarthritis (Dixon, Johnston, Rowley, & Pollard, 2008;Quinn et al, 2012), chronic pain (Dixon, Johnston, Elliott, & Hannaford, 2012), and chronic idiopathic axonal polyneuropathy (Schroder et al, 2007). However, the majority of psychological theories posit within-individual processes, and therefore, the importance of testing whether a model or theory can account for differences in behaviour within an individual is paramount (Curran & Bauer, 2011;.…”