ORIGINAL PAPER Alberto Parabiaghi ® Chiara Bonetto ® Mirella Ruggeri ® Antonio Lasalvia ® Morven Leese Severe and persistent mental illness: a useful definition for prioritizing community-based mental health service interventions Accepted: 3 February 2006 / Published online: 25 March 2006 j Abstract Objective There is a lack of consensus on the identification of seriously mentally ill patients (SMI). This study investigates the external and pre- dictive validity of an operationalized definition for the severity and persistency of mental illness applied to a sample of service users attending a community mental health service. Method The definition is based on the fulfilment of dysfunction (GAF £ 50) and ill- ness duration (‡2 yrs) criteria. The study was con- ducted with a two-year longitudinal design. External and predictive validity of the SMI definition were assessed against the diagnosis of psychosis. Re- sults Our data show evidence for an overall high predictive and external validity of the SMI definition and high sensitivity in predicting those with high burden of mental illness. Conclusions In order to identify people with high levels of psychiatric burden, the SMI working definition seems to be more useful than that simply based on diagnostic criteria. j Key words mental health services – psychotic disorders – burden of illness Introduction In recent years, the expression ‘‘severe and persistent’’ referred to persons with long-term psychiatric condi- tions has replaced the word ‘‘chronic’’, in order to avoid the association with the outdated and pessimistic concept of continuous and untreatable illness [19]. Defining severe and persistent mentally ill through operational criteria is useful for targeting: (a) mental illness costs in terms of direct treatment and support, morbidity and mortality (i.e. the reduced or lost value of productivity resulting from mental illness) [10, 18]; (b) distribution of resources to prioritize the severely mentally ill [25]; (c) equity in access to service (i.e. equal resources for those with equal need) according to a consensus based on a standardised definition [4]. A workgroup established under the auspices of the National Institute of Mental Health [16] proposed a consensus definition of the severe and persistent mentally ill, in order to find a common language among the ‘‘tower of Babel’’ [3] of definitions of serious mental illness (SMI); the NIMH definition was based on three criteria: (a) the diagnostic criterion, described as a non- organic psychosis and personality disorder [2]; (b) the duration criterion, which described the seriously mentally ill as having a long history of previous hos- pitalizations or outpatient treatment; (c) the disability criterion, which included dangerous or disturbing so- cial behaviour, moderate impairment in work and non- work activities and mild impairment in basic needs. Subsequently, Schinnar et al. [24] applied 17 SMI definitions proposed in USA between 1972 and 1987 (including the NIMH definition) to 222 psychiatric inpatients in Philadelphia and found estimates of SMI prevalence ranging from 4 to 88% of the treated population, depending on how broad the definitions’ A. Parabiaghi, MD ® C. Bonetto, Dr. Stat Prof. M. Ruggeri, Phd ® A. Lasalvia, PhD Dept. of Medicine and Public Health Section of Psychiatry and Clinical Psychology University of Verona Ospedale Policlinico Verona, Italy Dr. A. Parabiaghi (&) Dip.to di Medicina e Sanita ` Pubblica Sezione di Psichiatria e di Psicologia Clinica, Universita ` di Verona Policlinico GB Rossi, Piazzale L.A. Scuro, 10 37134 Verona, Italy Tel.: +39-045/8074441 Fax: +39-045/8074889 E-Mail: albertoparabiaghi@infinito.it M. Leese, PhD Section of Community Psychiatry (PRiSM) Health Service Research Dept. Institute of Psychiatry King’s College London London, England Soc Psychiatry Psychiatr Epidemiol (2006) 41:457–463 DOI 10.1007/s00127-006-0048-0 SPPE 48