Homelessness is worldwide an important societal issue as it can be considered as unacceptable and unfair. In the USA, each year over three million people experience homelessness of which 1,3 million children . In England 99.5000 households were officially recognised as newly homeless in 2007 . In the Flemish region each year 12.000 people get support in residential care for homeless persons .
Compared to a decade ago, the homeless population today is younger (between 30 and 50 years) with a growing number of women and children. This trend continues both in the USA and in Europe [4–7]. The way people become homeless can be attributed to a number of factors such as a disruptive family environment characterized by extreme poverty, marital discord, addiction, financial problems (no job, no money) and mental health problems [7–10].
Homelessness and health
Homeless people face many challenges. They lack the access to basic human needs such as shelter, clothing and healthy food, and have a disproportionally higher burden of disease than the average population . They suffer from a wide range of medical problems, acute as well as chronic, e.g. tuberculosis, [8, 12–14] hepatitis [7, 14], HIV [4, 7, 14–16], influenza  and skin and soft tissue infections [8, 13, 15, 16]. On top of the physical diseases, homeless people are more frequently caught in the downward spiral of having mental health problems or substance abuse: suffering from disorders such as depression, bipolar disorder or schizophrenia makes it even more difficult to find a job, stable housing or medical care [4, 10, 12, 15, 17]. These higher morbidity rates within the homeless population are also reflected in raised mortality rates [4, 7, 9, 15]: studies on the European and US situation report life expectancies between 41 and 47 years [4–6, 18, 19].
Homeless and health care utilisation
The literature concerning the health care utilisation of homeless people is scarce and almost exclusively reporting on the situation in the UK and the US. These studies show low utilisation rates of primary care among homeless people, with emergency care often being the only form of health care use [6, 7, 14, 16, 20–23]. As a result homeless people often consult with severe diseases and complications that could be prevented through earlier contact with a health care provider .
This particular pattern in health care use by homeless people is largely determined by the way the health care system is organised [7, 20–23]. In the USA, the health care system relies almost entirely on the private sector for both the financing  and the delivery of the health care. Most health care facilities are privately owned and operated. Some vulnerable groups are covered by social insurance programs such as Medicare, Medicaid and the State Children's Health Insurance Program. Even though these programs contribute to a more accessible health care for those groups, they are not able to provide access to all types of medical care nor do they cover all groups of vulnerable patients . Unsurprisingly, US based studies reporting on barriers in healthcare by homeless people describe several financial barriers to health care because of the lack of insurance (high insurance fees, refusing homeless patients because of missing identification cards,...), high costs of medication, competing priorities (finding housing or employment is more important than addressing health problems) [6, 16, 20]. Literature from the UK shows a slightly different picture, reflecting the particularity of the UK health care system. The UK has a universal health care system free at the point of service if people are registered with a GP . It is in fact this registration procedure which forms an important barrier to primary health care for homeless people in the UK: they often don't know they have to register or are scared off by the complexity of the registration procedure, GPs are reluctant to accept them on their list,... [7, 14, 21, 23, 24].
Although the UK provides a health service for all, marginal groups, such as homeless people, are poorly served and sometimes excluded. Since 1997 the NHS has focused on improved primary health care services for these special needs groups . Specialised general practices that register only homeless people have become more common . But despite the installation of this selective health care system, parallel to the universal system, the majority of the homeless is not aware of its existence and use emergency care as a substitute for primary care .
Information on the health care use of homeless people in other countries and the influence of health system characteristics seems to lack.
Furthermore, literature also reports on a wide range of factors and mechanisms not related to the organisation of the health care system contributing to the particular health care use patterns of homeless patients. The majority of these studies emphasize the importance of the attitude of health care providers towards homeless patients. Care is often postponed because homeless people feel labelled, stigmatized or considered as "problem patients"[11, 21].
In the region of Ghent (Belgium) the care for homeless people is organised in a unique way. In general, Belgium has a universal health care system with direct access to any general practitioner or specialist, without gate-keeping nor a patient-list. There is a fee-for-service system with about 30% co-payment for primary health care and 40% for specialist care. The lower socio-economic groups have a reduced co-payment of 8%. This co-payment is limited each year by an income-based threshold: the maximum bill . Since 1982, the legal possibility to work in a capitation system in primary health care has been put in practice. In the area of Ghent (a midsized city in Belgium with 225 000 inhabitants) the 19th century belt of deprived areas is to a large extent covered by Community Health Centres that provide interdisciplinary comprehensive primary health care using a capitation payment system. They adopt a universal approach in which all people residing in the neighbourhood can access the services of the centre. Less privileged residents such as the homeless staying in the area (e.g. frequenting the night shelters, living in squats, ...) are actively guided towards the community health centres by social welfare services. More specifically, there are formal agreements between the shelters for homeless people and the Community Health Centres in Ghent; in case people staying in the shelter need medical care, the nearby Community Health Centre is warned and (in most cases) a doctor comes to the shelter to see the patient. In rare occasions, the patient consults the doctor in the Community Health Centre (e.g. when he/she has been there before and he/she is able to walk to the Centre). Also for the payment of the costs, arrangements are made: all costs are directly refunded by the shelter or by the patient's Sickness Fund. When the patient is not insured, the Community Health Centres tend to ask no fee. Most homeless people living in the streets are usually known by the social workers working in the neighbourhood such as the outreachers and street corner workers. In case a homeless person needs medical care, the social workers refer him/her (or go with them) to one of the shelters (and usually do a follow-up whether the person did go to the shelter) or takes him/her directly to a doctor. There is no formal agreement between the street corner workers and the Community Health Workers, however the strong informal networks between them and the low financial and other thresholds of the Community Health Centres, makes that also the street corner workers usually lead the homeless people towards the Community Health Centres.
In one part of the area where there is no community health centre, people are guided towards a large group practice with a comparable way of working to the community health centres, except for the payment system which is fee-for-service based without co-payment for the patient.
Seen the particular organisation of the health care use in Ghent, we want to describe the accessibility of primary health care services, secondary care and emergency care for homeless people living in an area with a universal primary health care system and active guidance towards the system.