Treatments including multiple nonpharmacological components have beneficial effects on the key symptoms of fibromyalgia, although effects are limited and often do not persist. In this study, we examined different patterns of clinical progress and the dynamic interplay between predictors and outcomes over time.
Fibromyalgia patients (N=153; 135 women) followed a multidisciplinary group program spanning 12weeks, aimed at "regaining control over daily functioning". Anxiety, depression, pain coping and kinesiophobia were used as predictor variables. Outcome variables were pain severity, pain-related disability, physical functioning and functional interference. All variables were assessed at 3 moments: on the first and last day of treatment, and 12weeks after the last day of treatment. Overall treatment effects were analyzed using mixed model analyses. Latent class growth analysis identifying different treatment trajectory classes was used to investigate individual differences in treatment effects. Finally, cross-lagged structural equation models were used to investigate the dynamic interplay between predictors and outcomes over time.
Only a fourth to a third of the total group showed improvement on the outcome variables. These patients had lower baseline anxiety, depression and kinesiophobia, and improved more on anxiety, depression and kinesiophobia. Physical well-being had a stronger effect on anxiety and depression than vice versa. Physical functioning predicted relative changes in kinesiophobia, while kinesiophobia predicted relative changes in pain-related disability.
The results emphasize the importance of tailoring treatments to individual needs in order to improve overall effectiveness of treatment programs.