Background

Psychosis is a term used to describe a group of conditions in which severe symptoms of mental illness such as delusions and hallucinations occur, accompanied by the inability to distinguish between subjective experience and reality, and usually there is a lack of insight. Psychosis can be categorised as organic or functional. Organic psychoses can be caused by a variety of conditions including strokes, brain injury, encephalitis, Alzheimer£s disease, Parkinson£s disease, multiple sclerosis, temporal lobe epilepsy and brain tumours. Functional psychoses include schizophrenia and mood disorders such as mania, bipolar disorder and puerperal psychosis.

The prevalence of organic causes of psychosis varies with age, being lower in younger than older patients. Patients with psychosis may also have additional pathology such as space-occupying brain lesions. The main factors that would lead the clinician to suspect an organic cause of psychosis or additional pathology should be discovered during the initial clinical history and examination.

Indications that an organic cause is more likely include an acute onset, features of delirium such as clouding of consciousness, disorientation in time and place, disturbance of memory, impaired attention, fluctuation of conscious awareness and visual hallucinations. A neurological history and examination would look for a recent history of malignancy and/or focal neurological symptoms or signs, but these are not always present. Additional confirmatory tests would be used, depending on the diagnosis hypothesised. However, structural neuroimaging can also be used in all patients presenting with psychosis, irrespective of clinical suspicion, to screen for any additional pathology that would affect the clinical management of the patient. This may include structural magnetic resonance imaging (MRI) or computed tomography (CT) scanning, but frequently this is not undertaken in the UK.

Objectives

The objectives were to establish the clinical effectiveness and cost-effectiveness of structural neuroimaging (structural MRI and CT scanning) for all patients with psychosis, particularly a first episode of psychosis, relative to the current UK practice of selective screening only where it is clinically indicated.

Methods

A systematic review of studies (of any study design) reporting the additional diagnostic benefit of structural MRI, CT or combinations of these in patients with psychosis was conducted. The comparator was any current standard practice of diagnostic workup without structural neuroimaging. Only studies reporting clinically relevant outcomes were included. MEDLINE, EMBASE, the Cochrane Library, PsycINFO and CINAHL were searched from inception to November 2006. Inclusion, quality assessment and data extraction were undertaken in duplicate. Studies were assessed qualitatively only. The economic assessment consisted of a systematic review of economic evaluations and the development of a threshold analysis to predict the gain in quality-adjusted life-years (QALYs) required to make neuroimaging cost-effective at commonly accepted threshold levels (£20,000 and £30,000 per QALY). Sensitivity analyses of several parameters including prevalence of psychosis were performed.

Results

Discussion and conclusions

First-episode psychosis is not clearly defined or universally accepted. There is a paucity of good-quality evidence on the clinical benefits of structural neuroimaging in psychosis on which to base this health technology assessment. The evidence to date suggests that if screening with structural neuroimaging was implemented in all patients presenting with psychotic symptoms under 65 years old, little would be found to affect clinical management in addition to that suspected by a full clinical history and neurological examination. From an economic perspective, the outcome is not clear. The strategy of neuroimaging for all is either cost-incurring or cost-saving (dependent upon whether MRI or CT is used) if the prevalence of organic causes is around 1%. However, these values are nested within a number of assumptions, meaning that they have to be interpreted with caution.

Publication

• Albon E, Tsourapas A, Frew E, Davenport C, Oyebode F, Bayliss S, et al. Structural neuroimaging in psychosis: a systematic review and economic evaluation. Health Technol Assess 2008;12(18). [PubMed: 18462577]

NIHR Health Technology Assessment Programme

The Health Technology Assessment (HTA) Programme, part of the National Institute for Health Research (NIHR), was set up in 1993. It produces high-quality research information on the effectiveness, costs and broader impact of health technologies for those who use, manage and provide care in the NHS. 'Health technologies£ are broadly defined as all interventions used to promote health, prevent and treat disease, and improve rehabilitation and long-term care.

The research findings from the HTA Programme directly influence decision-making bodies such as the National Institute for Health and Clinical Excellence (NICE) and the National Screening Committee (NSC). HTA findings also help to improve the quality of clinical practice in the NHS indirectly in that they form a key component of the 'National Knowledge Service£.

The HTA Programme is needs-led in that it fills gaps in the evidence needed by the NHS. There are three routes to the start of projects.

First is the commissioned route. Suggestions for research are actively sought from people working in the NHS, the public and consumer groups and professional bodies such as royal colleges and NHS trusts. These suggestions are carefully prioritised by panels of independent experts (including NHS service users). The HTA Programme then commissions the research by competitive tender.

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Some HTA research projects, including TARs, may take only months, others need several years. They can cost from as little as £40,000 to over £1 million, and may involve synthesising existing evidence, undertaking a trial, or other research collecting new data to answer a research problem.

The final reports from HTA projects are peer-reviewed by a number of independent expert referees before publication in the widely read journal series Health Technology Assessment.

Criteria for inclusion in the HTA journal series

Reports are published in the HTA journal series if (1) they have resulted from work for the HTA Programme, and (2) they are of a sufficiently high scientific quality as assessed by the referees and editors.

Reviews in Health Technology Assessment are termed 'systematic£ when the account of the search, appraisal and synthesis methods (to minimise biases and random errors) would, in theory, permit the replication of the review by others.

The research reported in this issue of the journal was commissioned and funded by the HTA Programme on behalf of NICE as project number 06/58/01. The protocol was agreed in November 2006. The assessment report began editorial review in July 2007 and was accepted for publication in November 2007. The authors have been wholly responsible for all data collection, analysis and interpretation, and for writing up their work. The HTA editors and publisher have tried to ensure the accuracy of the authors£ report and would like to thank the referees for their constructive comments on the draft document. However, they do not accept liability for damages or losses arising from material published in this report.

The views expressed in this publication are those of the authors and not necessarily those of the HTA Programme or the Department of Health.

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