Moderating factors for the effectiveness of group art therapy for schizophrenia: secondary analysis of data from the MATISSE randomised controlled trial.

Purpose: Although some studies suggest that art therapy may be useful in the treatment of negative symptoms of schizophrenia, a recent large trial of group art therapy found no clinical advantage over standard care, but the study population was heterogeneous and uptake of the intervention was poor. This study aimed to investigate whether art therapy was more effective for specific subgroups of patients.

Methods: Secondary analysis of data from a randomised controlled trial of group art therapy as an adjunctive treatment for schizophrenia (n = 140) versus standard care alone (n = 137). Positive and Negative Syndrome Scale scores at 12 months were compared between trial arms. Interaction between intervention effect and different subgroups, including those with more severe negative symptoms of schizophrenia, and those who expressed a preference for art therapy prior to randomisation, was tested using a linear mixed model.

Results: The clinical effectiveness of group art therapy did not significantly differ between participants with more or less severe negative symptoms [interaction for difference in PANSS = 1.7, 95 % CI (-8.6 to 12.1), P = 0.741], or between those who did and did not express a preference for art therapy [interaction = 3.9, 95 % CI (-6.7 to 14.5), P = 0.473]. None of the other exploratory subgroups suggested differences in intervention effect.

Conclusions: There was no evidence of greater improvement in clinical symptoms of schizophrenia for those with more severe negative symptoms or those with a preference for art therapy. Identification of patients with schizophrenia who may benefit most from group art therapy remains elusive.