Testing integrated behavioural and biomedical models of activity and activity limitations in a population-based sample

Abstract

Purpose: The predictive utility of an integrated model of disability is tested. The integrated model incorporates an impairment based model (International Classification of Functioning, Disability and Health (ICF)) and the behavioural models. Methods: Community dwelling adults (n = 628) completed a postal questionnaire measuring the integrated model. The ability of the model to predict disability in the form of activity limitations (ALs) and walking, in the full community sample and in respondents reporting chronic pain was tested. Results: In both the community and chronic pain samples each version of the integrated model explained a majority (55%–67%) of the variance in ALs but only 11%–29% of the variance in walking behaviour (WB). Impairment directly predicted ALs but did not directly predict WB. Control related cognitions were direct predictors, and mediators, of the relationship between bodily impairment and both ALs and WB. In addition, intentions and outcome expectancies predicted WB. Self-efficacy (SE) was the most consistent predictor of both ALs and WB. Conclusions: An integrated model which combines psychological constructs and impairment is required for an adequate understanding of ALs. By contrast, behavioural models, but not degree of impairment, are necessary to explain activity levels.

Implications for Rehabilitation

• Activity limitations are typically predicted by impairment based models, whereas activity is typically predicted by cognition based models of behaviour.

• This study examines whether a theoretical model that incorporated both cognition and impairment factors could predict the activity of walking and activity limitations in a community sample of people with and without chronic pain.

• An adequate understanding of activity limitations required a model that incorporated impairment and cognitions, whereas impairment factors were not required for an understanding of walking behaviour.

• Interventions to reduce or manage activity limitations might usefully incorporate techniques to change cognitions, especially self-efficacy perceptions.

Keywords::

• Chronic pain
• disability
• ICF
• social cognitive theory
• theory of planned behaviour
• walking

Acknowledgements

The authors would like to thank the Scottish Primary Care Research Network and the participating GP practices for their work for this study. This study was funded by the Chief Scientist Office Edinburgh.

Declaration of Interests: The authors report no declaration of interests.

Notes

1 In order to examine the predictive validity of the TPB it is necessary to specify precisely the target behaviour and to measure the TPB cognitions toward that specific behaviour. Thus, it would have been necessary to specify a participation restriction behaviour of relevance to each participant, and to measure cognitions towards that behaviour; this was not possible within the constraints of a postal questionnaire.

2 The measurement validation studies employed the method of Discriminant Content Validation (DCV) to establish the relationship between measurement items and constructs from the ICF. In the DCV studies, expert judges decided whether each measurement item was a ‘match’ or ‘no match’ to the theoretical definitions of: impairment, activity limitations and participation restrictions. Judges also provided a confidence rating for each judgement. One sample t-tests then identified pure measurement items; items that were matched to one theoretical construct only.