Classification of Psychotherapy Interventions for People with Schizophrenia: Development of the Nottingham Classification of Psychotherapies
Authors: Roberts Matthew T. , Shokraneh Farhad , Sun Yanli , Groom Maddie , Adams Clive E. 
Published: August 2020

Background

Currently, there is no accepted system for the classification of psychotherapies for application within systematic reviews is timely.

Objective

To devise a system for classification of psychotherapy interventions – for use, initially, in systematic reviews.

Methods

Cochrane Schizophrenia’s Register used as the source of RCTs. After being piloted and refined at least twice, finally we applied it to all relevant trials within the register. Basic statistical data already held within the register were extracted and used to calculate the distribution of schizophrenia research by form of psychotherapy.

Findings

The final classification system consisted of six definable broad ‘boughs’ two of which were further subdivided into ‘branches’. The taxonomy accommodated all psychotherapy interventions described in the Register. Of the initial 1645 intervention categories within the Register, after careful recoding, 539 (33%) were psychotherapies (234 coded as ‘Thought/Action’ (cognitive & behavioural) - 1495 studies; 135 ‘Cognitive Functioning’ - 652 studies; 113 ‘Social’ - 684 studies; 55 ‘Humanistic’ - 272 studies; 23 ‘Psychoanalytic/dynamic’ - 40 studies; and 63 ‘Other’ - 387 studies).

For people with schizophrenia, across categories, the average size of psychotherapy trial is small (107) but there are notable and important exceptions.

Conclusion

We reported a practical method for categorising psychotherapy interventions in evaluative studies with applications beyond schizophrenia. A move towards consensus on the classification and reporting of psychotherapies is needed.

Clinical Implications

This classification can help the clinicians, clinical practice guideline developers, and evidence synthesis experts to recognise and compare the interventions from same or different classes.

Summary Box

What is already known about this subject?

Effective classification of medical interventions is a perquisite for their effective identification, detection, and grouping. This in turn is essential for comprehensive identification of randomised control trials (RCTs) for inclusion in systematic reviews.

A vast range of psychological therapies for schizophrenia exist, however there is a great degree of heterogeneity in their methods, and little consistency in their nomenclature.

Classification of interventions for schizophrenia exists for pharmacological therapies. However only limited attempts have been made to develop such a classification for psychotherapies, and no literature-based classifications have been attempted for use in research.

What are the new findings?

The vast majority of psychotherapy interventions for schizophrenia can be consistently and systematically assigned to five broad categories: Thought/Action, Cognitive Functioning, Social, Humanistic, and Psychoanalytic/Psychodynamic. A small minority of emerging or unique psychotherapy interventions do not fit into any of these five categories.

Using the same classification system these categories can in turn be subdivided into branches, allowing similar forms of psychotherapy to identified with greater detail, and allowing systematic reviews of greater specificity to be conducted.

This classification was applied to Cochrane Schizophrenia’s comprehensive register of schizophrenia RCTs. It was demonstrated to be an effective method for identifying and grouping different schizophrenia psychotherapy RCTs for the purposes of conducting systematic reviews.

The mean size of schizophrenia psychotherapy RCTs is approximately one hundred participants, consistent across different categories of psychotherapies. Thought/Action interventions – such as cognitive behavioural therapies – account for the largest proportion of schizophrenia psychotherapy RCTs. Only a small minority of schizophrenia psychotherapy RCTs investigate humanistic and psychoanalytic/psychodynamic therapies.

How might it impact on clinical practice in the foreseeable future?

The classification system we have developed can be used for the accurate identification and grouping of different types of psychotherapies. This will allow more comprehensive, accurate, and specific systematic reviews to be conducted – in turn producing better quality evidence on the effectiveness of different forms of psychotherapy for schizophrenia.

The classification system also has applications beyond research – and likely beyond schizophrenia – including providing a framework for laypersons and clinicians to better understand and recognise different forms of psychotherapy. It also provides a contribution, and an impetus, towards improving consensus around common language and classification of psychotherapies.

The data on study size and distribution by category of psychotherapy – which we have produced by applying our classification system to Cochrane Schizophrenia’s comprehensive register of schizophrenia RCTs – may illuminate avenues for future research into schizophrenia psychotherapy, and identify areas in which RCTs in this area can be improved.