Dealing with heterogeneity in treatment implementation: an example from music therapy in psychiatry

Christian Gold

Background: Heterogeneity in psychotherapeutic intervention processes may stem from multiple sources, including differences between therapists, clients, theoretical orientations, therapy settings, and cultural contexts. These may reflect clinically important differences and should be adequately addressed in systematic reviews. Current recommendations include subgroup analyses and meta-regression, but both can be problematic both practically and conceptually [1].
Objective: To examine sources of heterogeneity in treatment implementation in music therapy for schizophrenia.
Methods: Using a sample of studies identified for a Cochrane Review [2], we explore how music therapy was conceptualised and carried out in these studies, and how this is related to a standard definition of music therapy [3], and to clinical reports of music therapy in psychiatry [4].
Results: We identified the following problems: - In relation to the definition of music therapy, it is often difficult to determine the precise boundary between music therapy and non-music therapy. - Variation between studies occurs on several dimensions and may in many cases better be described as continuous rather than categorical. - There is a considerable gap between music therapy as typically implemented in clinical practice and music therapy as typically implemented in studies.
Conclusions: Heterogeneity in the implementation of psychosocial interventions such as music therapy is manifold and complex. It is unlikely that it will disappear by separating smaller sub-groups, developing more rigid definitions, or constraining clinical practice. There is a need for studies that are more closely linked to clinical practice, and a need for methodological developments that provide a more adequate way of dealing with complex heterogeneity in systematic reviews.
References: 1. Clarke M, Oxman AD, editors. Cochrane Reviewers’ Handbook 4.2.0 [updated March 2003]. In: The Cochrane Library, Issue 2, 2003. Oxford: Update Software. Updated quarterly. 2. Gold C, Bentley K, Wigram T. Music therapy for schizophrenia or schizophrenia-like illnesses (Protocol for a Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Chichester, UK: John Wiley & Sons, Ltd. 3. Bruscia KE. Defining music therapy. 2nd ed. Gilsum, NH: Barcelona; 1998. 4. Wigram T, De Backer J. Clinical applications of music therapy in psychiatry. London: Jessica Kingsley; 1999.

Ottawa 2004 O-066