Prediction of a single psychotic episode: A 7.5-year, prospective study in first-episode psychosis
Introduction
Despite previous longitudinal studies showing that around 20% of patients who suffer from psychotic disorders will only experience one psychotic episode (Linszen et al., 2001, Shepherd et al., 1989, Wiersma et al., 1998), little research has been dedicated to identifying this subgroup of patients. There are many potential benefits to both research and clinical practice in establishing the factors associated with only experiencing a single psychotic episode (SPE). Firstly, the identification of a separate group of patients who achieve clinical remission with a non-relapsing course of illness may enable more benign treatment approaches tailored to this subgroup's particular needs, minimizing side effects associated with prolonged exposure to antipsychotic medication (Alvarez-Jimenez et al., 2008, Alvarez-Jimenez et al., 2009a, Alvarez-Jimenez et al., 2009b, an der Heiden and Hafner, 2000, Bola and Mosher, 2002, Carpenter and Heinrichs, 1981). Secondly, establishing treatment and environmental factors that have an effect on the long-term course of the illness would shed light on modifiable prognostic characteristics. This would, in turn, inform public health policies and the development of novel therapies targeting these factors (van Os and Kapur, 2009).
A study that aims to discriminate factors associated with experiencing a SPE from potential confounders needs to meet strict methodological criteria. Firstly, a prospective first-episode psychosis (FEP) study is necessary in which participants are recruited and assessed at first treatment contact, free from the confounding effects of previous treatment interventions or secondary morbidity (Ram et al., 1992). Secondly, such a study should include recruitment of an incident, multi-diagnostic FEP cohort, as opposed to convenience samples of limited diagnostic range which are likely to create selection biases that impede generalizability of the findings to ‘real world’ settings (Henry et al., 2007). Thirdly, the study should be properly powered to investigate the influence of relevant predictors independent of potential confounders. Finally, the duration of follow-up should extend beyond the critical period (i.e. the first 5 years after the onset of psychosis) after which the level of disability sustained, or recovery achieved, is thought to endure into the long-term (Birchwood et al., 1998, Crumlish et al., 2009).
Only a few longitudinal FEP studies have conducted prospective assessments beyond 5 years; however they have exclusively focused on patients with schizophrenia (an der Heiden and Hafner, 2000, Breier et al., 1991, Mason et al., 1995, Munk-Jorgensen and Mortensen, 1989, Wiersma et al., 1998), recruited convenience or small samples of newly admitted inpatients (Bottlender et al., 2003, Carpenter and Strauss, 1991, Linszen et al., 2001), or they have examined predictors of recovery without isolating the subset of patients who only experience one psychotic episode (Crumlish et al., 2009, Robinson et al., 2004) or controlling for potential confounders (Robinson et al., 2004). To date, no single study has reliably characterized the group of patients who only experience one psychotic episode or identified prognostic factors for this subgroup independent of potential confounders.
In the present study we recruited a large, epidemiologically representative cohort of FEP patients presenting at a specialized FEP service followed them up over a 7.5-year period. We sought to: 1) characterise the subgroup of FEP patients who experienced a SPE; 2) identify independent predictors of SPE after controlling for potential confounders; and 3) evaluate an hypothesised model of the relationships between relevant predictive factors and experiencing a SPE.
Section snippets
Design and setting
The study participants were recruited into the Early Psychosis Prevention and Intervention Centre (EPPIC) long-term follow-up study, a longitudinal 7.5-year follow-up study of consecutive FEP patients admitted into EPPIC. The EPPIC programme is a front-line, youth-orientated, specialist mental health programme which provides comprehensive, community-based treatment for FEP patients originating from a geographically defined catchment area in metropolitan Melbourne, Australia with a population of
Follow-up and characteristics of the sample
Four hundred and thirteen patients agreed to take part in the study, and reliable information on number of psychotic episodes were available for 274 participants from the 7.5-year follow-up interviews. Loss to follow-up (n = 139) was due to refusal to be interviewed (n = 79; 19.1%), previous refusal of all further follow-up (n = 3; 0.7%), deceased (n = 26; 2.3%), failure to locate the participant for interview (n = 27; 6.5%), or lack of reliable data on number of psychotic episodes despite being
Discussion
This is the first study, to our knowledge, to characterise the subgroup of FEP patients who experience a single psychotic episode (SPE) and remain in clinical remission during a long-term follow-up extending beyond the critical period for psychosis. Both environmental and treatment-related variables were shown to be relevant predictors of experiencing SPE. Shorter DUP, more rapid time to response to treatment, and ‘no parental loss’ emerged as the strongest independent predictors of
Role of funding source
This work was supported by the Victorian Health Promotion Foundation (grant number 91-0084C) Victoria, Australia; the Australian National Health and Medical Research Council (grant number 350241) Canberra, Australian Capital Territory, Australia; and the Colonial Foundation, Victoria, Australia. The funding bodies had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.
Contributors
MA-J and JF-G designed the study and wrote the first draft of the manuscript. E-K and AR-Y contributed to the design of the study and critically revised the manuscript. PD-M, HJ-J, H-H, LP-H, MG-H, GP-A and SM-H supervised the research project and critically revised the manuscript. All authors contributed to and have approved the final manuscript.
Conflict of interest
The authors report no additional financial or other affiliation relevant to the subject of this article.
Acknowledgments
This work was supported by the Victorian Health Promotion Foundation (grant number 91-0084C) Victoria, Australia; the Australian National Health and Medical Research Council (grant number 350241) Canberra, Australian Capital Territory, Australia; and the Colonial Foundation, Victoria, Australia. The funding bodies did not contribute to the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.
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