Date Published: December 2, 2008
Publisher: Public Library of Science
Author(s): Seena Fazel, Vivek Khosla, Helen Doll, John Geddes, John McGrath
Abstract: BackgroundThere are well over a million homeless people in Western Europe and North America, but reliable estimates of the prevalence of major mental disorders among this population are lacking. We undertook a systematic review of surveys of such disorders in homeless people.Methods and FindingsWe searched for surveys of the prevalence of psychotic illness, major depression, alcohol and drug dependence, and personality disorder that were based on interviews of samples of unselected homeless people. We searched bibliographic indexes, scanned reference lists, and corresponded with authors. We explored potential sources of any observed heterogeneity in the estimates by meta-regression analysis, including geographical region, sample size, and diagnostic method. Twenty-nine eligible surveys provided estimates obtained from 5,684 homeless individuals from seven countries. Substantial heterogeneity was observed in prevalence estimates for mental disorders among the studies (all Cochran’s χ2 significant at p < 0.001 and all I2 > 85%). The most common mental disorders were alcohol dependence, which ranged from 8.1% to 58.5%, and drug dependence, which ranged from 4.5% to 54.2%. For psychotic illness, the prevalence ranged from 2.8% to 42.3%, with similar findings for major depression. The prevalence of alcohol dependence was found to have increased over recent decades.ConclusionsHomeless people in Western countries are substantially more likely to have alcohol and drug dependence than the age-matched general population in those countries, and the prevalences of psychotic illnesses and personality disorders are higher. Models of psychiatric and social care that can best meet these mental health needs requires further investigation.
Partial Text: Around 380,000 individuals in the United Kingdom  and 740,000 individuals in the United States  are reported to be homeless at any given time. Although most live in sheltered accommodation such as emergency hostels, bed and breakfasts, squats, or other temporary accommodation, a recent US report has estimated that 44% are unsheltered, equivalent to over 300,000 people living on the streets .
We searched for surveys that estimated the prevalence of psychotic illness, major depression, personality disorder, alcohol dependence, and substance dependence in homeless people, published between January 1966 and December 2007. We searched computer-based literature indexes (EMBASE, MEDLINE, PsycINFO), scanned relevant reference lists, searched relevant journals by hand, and corresponded with authors. For the database search, we used combinations of keywords relating to psychiatric illnesses (e.g., mental*, psych*, depress*, substance/drug*/alcohol* abuse/dependence, personality) and being homeless (e.g., homeless*, roofless, shelter*). Non-English articles were translated. MOOSE guidelines were followed (Text S1).
The final sample consisted of 29 studies published between 1979 and 2005 (Table 1) [6–10,38–59]. The studies included a total of 5,684 homeless individuals. Eleven reports reported data on men (n = 1,827) [7,38,40–43,45,47–49,60], 14 included mixed gender samples (n = 3,381) [6,8,39,44,50–54,61], and four investigated women (n = 476) [9,10,40,55]. In the surveys with mixed samples, 82% of the individuals were men (weighted average). The weighted average age of men (reported in eight reports) and women (from four reports) was 41.2 and 33.8 y, respectively. Average age of the mixed samples was 40.1 y (from ten studies). Ten studies were published before 1990 [6–8,10,39,40,42,45,46,49]. Ten reports were from the US (n = 2,019) [6,8,10,38,39,42,49,51,52,55], eight from the UK (n = 1645) [7,44,45,53,56–58,61], six from Germany (n = 624) [9,41,47,48,59,60], two from Australia (n = 473) [40,46], and one each from France (n = 715) , The Netherlands (n = 150) , and Greece (n = 58) .
This systematic review of serious mental disorders in homeless persons identified 29 surveys including 5,684 individuals. There are three main findings. First, the most common mental disorders appeared to be alcohol and drug dependence, with random effects pooled prevalence estimates of 37.9% (95% CI 27.8%–48.0%) and 24.4% (95% CI 13.2%–35.6%), respectively. Second, the prevalence estimates for psychosis were at least as high as those for depression, a finding in marked contrast from community estimates of these conditions [62,63], and in other at-risk groups such as prisoners  and refugees , in whom depression is more common. Third, although high prevalences were reported for serious mental disorders, their substantial heterogeneity suggests that service planning should not rely on our summary estimates but commission local surveys of morbidity to quantify mental health needs.