Background
Programs for teaching self-management skills to people with chronic diseases can reduce anxiety and depression, but those benefits appear to be small.
Aim
We tested the hypothesis that important differences among the program’s participants are “averaged out” in summary statistics – that the benefits are actually large for some participants and small for others.
Methods
Adults with various chronic diseases (n=456) participated in the Chronic Disease Self-Management Program. We focused on two of the many outcome indicators: anxiety and depression. Both were measured four times over one year. To reveal latent trajectories – distinct patterns of change over time – we used Growth-Mixture Modeling (GMM) and the Bayesian information criterion.
Results
GMM identified two trajectories. One trajectory began from a low-anxiety baseline, and it showed almost no change. The other trajectory began from a clinically important high-anxiety baseline, and it showed marked improvement, but that improvement was followed by deterioration back to the baseline level, i.e. decay of impact. Almost half of the participants (46%) had the decay-of-impact trajectory. The results for depression were similar (51%).
Conclusion
First, GMM identified two distinct trajectories of change in anxiety and depression after a health-education intervention. Second, about half of the participants had a large decay of impact. If those people can be identified early, then “booster-session” reinforcements can be offered to them specifically, to help them maintain their new self-management skills. GMM can change the way these programs are evaluated, directing attention away from overall averages and toward pattern-defined groups.
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