Assessing the Validity of a Stage Measure on Physical Activity in a Population-Based Sample of Individuals With Type 1 or Type 2 Diabetes

Abstract

This study was designed to test the validity of a transtheoretical model's physical activity (PA) stage measure with intention and different intensities of behavior in a large population-based sample of adults living with diabetes (Type 1 diabetes, n = 697; Type 2 diabetes, n = 1,614) and examine different age groups. The overall specificity (classified correctly as inactive) for Type 1 diabetes was 69.3% based on the percentage of individuals in precontemplation, contemplation, and preparation not meeting Canada's PA guidelines. Sensitivity (classified correctly as active) was 82.5% based on the proportion of active participants in action and maintenance. In the Type 2 diabetes group, the overall specificity and sensitivity was 63.9% and 88.2%, respectively. No significant differences were found between the diabetes groups for stage distribution patterns, and sensitivity and specificity values. The majority of the study hypotheses related to intention and behaviors were confirmed, providing further supportive evidence for the utility of this PA staging measure for the diabetes population.

Keywords:

• stages of change
• transtheoretical model
• physical activity
• diabetes mellitus
• validation
• sensitivity
• specificity

ACKNOWLEDGEMENTS

The first author is supported by Salary Awards from the Alberta Heritage Foundation for Medical Research and the Canadian Institutes for Health Research (CIHR). The second author was funded through a CIHR New Emerging Team Grant during the time of this research. The fourth author is supported by the Canadian Research Chair Program. The sixth author is funded by the Ontario Ministry of Health, Scientist Career Award. We would like to thank Kylie Hugo for her editorial assistance on this manuscript.

Notes

¹600 MET/Week is equivalent to 150 minutes of moderate physical activity/Week (Brown & Bauman, 2000)

²ΔM = mean difference between adjacent stage groups, i.e. Preparation and Action.

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