Intimate partner abuse
For the purpose of this review, intimate partner abuse (often termed domestic violence) is defined as abuse of a woman by a male or female partner who currently is, or formerly was, in an intimate relationship with the woman. Domestic violence against men is not included in the review. Intimate partner abuse perpetrated by women or men against male partners or ex‐partners also occurs. However, the majority of abuse with serious health and other consequences is that committed by men or women against their female partners (Henwood 2000). Abuse perpetrated by ex‐partners is included in the review since often the greatest risk to a woman is when she is preparing to leave or has just left her partner. It is estimated that between 65% and 75% of women killed by abusive partners are killed while leaving or after already leaving the relationship (Wilson 1993; FGTFDSV 1997). Intimate partner abuse may take various forms, including physical violence (ranging from slaps, punches, and kicks to assaults with a weapon and homicide), sexual violence (such as forced sex, or forced participation in degrading sexual acts), emotionally abusive behaviours (such as stalking, surveillance, threats of abuse, threats to remove children from the household, prohibiting a woman from seeing her family and friends, ongoing belittlement or humiliation, or intimidation), economic restrictions (such as preventing a woman from working, confiscating her earnings, restricting access to funds), and other controlling behaviours (Watts 2002). Additionally, abused disabled women may experience withholding of orthotic equipment, medications, transportation, or essential assistance with personal tasks, such as dressing or getting out of bed (Nosek 1998). Often the different forms of abuse co‐exist, but they may also present individually (Taft 2001). Partner abuse may also co‐exist with other forms of domestic violence, such as that perpetrated by other family members, but such abuse is not the focus of this review.

Prevalence of intimate partner abuse
The 1996 British Crime Survey for England and Wales found that 23% of women reported being physically assaulted by a current or former partner at some time in their lives, and these figures increased to 26% when frightening threats were included (Mirrlees‐Black 1991). More recently, the largest study in the United Kingdom among women general practice patients found that 41% had ever experienced physical or sexual violence from a partner or former partner and 17% had experienced it within the last year (Richardson 2002).

The UK experience described above is characteristic of that found in other countries. Abuse of women by their partners or ex‐partners is a worldwide phenomenon (Watts 2002). Research in the United States indicates that nearly one in three adult women experience at least one physical assault by a partner during adulthood and four million American women experience a serious assault by a partner during an average 12‐month period (APAPTFVF 1996). Fifty‐one cross‐sectional population surveys conducted in various countries on behalf of the World Health Organisation show a lifetime prevalence of between 10%‐50% and between 3%‐52% for the experience of physical violence in the previous year (WHO 2001; Heise 1999). Some examples from the WHO programme are given below (Table 1).

Disabled women may be at even greater risk of being abused. In a North American sample of women with physical disabilities, 62% reported having experienced emotional, physical, or sexual abuse (Nosek 1998).

Impact on health of women and use of services
Intimate partner abuse can have short‐term and long‐term negative health consequences for survivors, even after the abuse has ended (Campbell 2002). A World Development Report from the United Nations emphasises that such violence is a significant cause of death and disability on a world‐wide scale (SSI 1996) and the World Health Organisation highlights violence against women as a priority health issue (WHO 1998).

Physical health of abused women
Intimate partner abuse is one of the most common causes of injury in women. In the largest UK study of women general practice patients, 16% reported being punched in the face, 20% were punched on the body, arms or legs, and 13% were kicked on the floor. Of these women, 50% required medical attention for their injuries (Richardson 2002). Similar figures emerge from research conducted in hospital emergency rooms. In the USA a recent review estimated that 50% of all acute injuries and 21% of all injuries in women requiring urgent surgery were the result of partner abuse (Guth 2000).

In 1997, two women in England and Wales were killed each week by their current or former partners (HMSO 1998) a figure that represents 47% of all female homicides for that year (HMSO 1997). In Scotland, for homicides recorded over a ten‐year period (1991‐2000), 54% of the female victims aged 16‐59 were killed by their partner (SESS 2001). In the United States and Canada, 31%‐60% of murders of women during the 1990's were committed by intimate partners (Craven 1997; Crawford 1997; Brock 1999). Percentages may be even higher in less industrialised countries, but there is little global data on the murder of abused women (Gartner 1990). Suicide is also associated with intimate partner abuse in both industrialised and non‐industrialised countries, as is attempted suicide (Counts 1987). Abused women are five times more likely to attempt suicide compared with women who have not experienced such violence (Stark 1996).

Abused women experience many chronic health problems. The most consistent and largest physical health difference between abused and non‐abused women is the experience of gynaecological problems (e.g. sexually‐transmitted diseases, vaginal bleeding and infection, genital irritation, chronic pelvic pain, urinary‐tract infections) (Campbell 2002). Population based studies from the United States show that the likelihood of abused women exhibiting these symptoms are three times greater than average (McCauley 1995). Other conditions include chronic pain (e.g. headaches, back pain) and central nervous system symptoms (e.g. fainting and seizures),(Campbell 2002; DiazOlavarrieta 1999) self‐reported gastrointestinal symptoms (e.g. loss of appetite, eating disorders) and diagnosed functional gastrointestinal disorders (e.g. irritable bowel syndrome) (DiazOlavarrieta 1999; Coker 2000) and self‐reported cardiac symptoms (e.g. hypertension, chest pain) (Tollestrup 1999).

Health of abused women during pregnancy
Research evidence shows that intimate partner abuse continues when women becomes pregnant ‐ indeed, it may even escalate (Gazmararian 2000; Mezey 1997). A review by Campbell shows that prevalence rates of abuse during pregnancy are very similar in industrialised and non‐industrialised countries (Campbell 2002). Most studies in the United States show a prevalence of between 4%‐8%. This compares with 6%‐8% during the past year in the United Kingdom, 6%‐7% in Canada, at least 7% in South Africa, 11%‐21% in Sweden, and 13% in Nicaragua. The health risks for abused mothers and their unborn children can be serious. The most serious outcome is the death of the mother (Parsons 1999) or the foetus (McWilliams 1993; Jejeebhoy 1998). Intimate partner violence is also associated with low birth weight (Murphy 2001) premature birth and foetal injury (Mezey 1997).

Psychosocial health of abused women
The impact of partner violence has psychological parallels with the trauma of being taken hostage and subjected to torture (Dutton 1992; Herman 2001). The most prevalent mental health sequelae of intimate partner abuse are depression and post‐traumatic stress disorder (McCauley 1995; Ratner 1993; Golding 2002). Women living in abusive relationships are three times more likely to be diagnosed depressed or psychotic (Stark 1996) and they often have feelings of low self‐esteem and hopelessness (Kirkwood 1993). Living in a violent relationship may exacerbate a predisposition to depression; however, a woman's first exposure to abuse can also be a causal factor for subsequent depression (Campbell 1999; Silva 1997). Work in the United States shows that abused women are nearly four times as likely to suffer from post‐traumatic stress disorder compared with non‐abused women, and this can be directly related to experiencing intimate partner abuse (Golding 2002; Silva 1997). There is also evidence from the United States, Scandinavia and Papua New Guinea that increased suicidal tendencies are associated with abuse (Counts 1987; Golding 2002). Other signs of emotional distress associated with intimate partner abuse are self‐harm and para‐suicide (Stark 1996; Heath 2003) anxiety, insomnia and social dysfunction (Ratner 1993). A Nicaraguan study found that 70% of cases of emotional distress were believed to be a direct consequence of abuse (Ellsberg 1999).

In industrialised countries a further mental health problem associated with partner violence is the abuse of alcohol and drugs (McCauley 1995; Ratner 1993; Golding 2002). Women who have experienced physical or psychological violence are fifteen times more likely to abuse alcohol and nine times more likely to abuse drugs than are non‐abused women (Stark 1996). There is also evidence that alcohol and drug abuse for some women is directly attributable to intimate partner violence (Stark 1996).

The impact of intimate partner abuse on health service usage
Women experiencing intimate partner abuse present very frequently to health services and require wide‐ranging medical services (Campbell 2002; Davidson 2001). They are admitted to hospital more often than are non‐abused women and are issued more prescriptions (Koss 1991; Wisner 1999 A Canadian study set in a hospital accident and emergency department found that abused women access medical care three times more often than do non‐abused women (Ratner 1993). There is also evidence of a positive linear relationship between severity of abuse and the use of health‐care services (Koss 1991).

It is difficult to calculate the societal economic impact of intimate partner abuse but the costs are high. In a study conducted in east London, it was estimated that the public sector costs for providing services to women and children facing violence was £7.5 million (GBP). Extrapolating these figures to the whole of the Greater London area, it was estimated that the costs were around £278 million pounds per annum (Stanko 1998). In a study that compared health plans in the United States, a 92% increase in costs was associated with partner abuse, with much of this increased cost being attributable to providing mental health care provision (Wisner 1999). Thus, in addition to the very serious individual health consequences associated with abuse, there are also wider economic implications for society.

Interventions to improve the health consequences for women who are experiencing or have previously experienced domestic violence
Interventions may be primary, secondary or tertiary. In the context of domestic violence, primary interventions are concerned with preventing the onset of abuse, secondary interventions aim to prevent further abuse, and tertiary interventions deal with the consequences of abuse once the abuse has ceased. Thus it is secondary and tertiary interventions that are of relevance here.

A range of such interventions have been evaluated. Essentially these may be classified as interventions aimed at directly helping abused women (such as the provision of advocacy or therapy), and those aimed at indirectly helping abused women by improving the response of the professionals with whom they come into contact (such as the introduction of screening protocols or the provision of education and training about domestic violence). In order to have clear evidence about what professionals can do safely and effectively to decrease the impact of intimate partner abuse on women, all such interventions need to be evaluated. To this end, we are conducting a suite of systematic reviews evaluating the effectiveness of interventions to improve the health consequences for women who are experiencing or have previously experienced domestic violence.

In this review we examine the effectiveness of individual advocacy interventions. Future companion reviews will address the effectiveness of psychosocial therapeutic interventions for abused women, and screening and educational interventions aimed at the professionals who come into contact with these women.

The meaning of the term advocacy differs between countries. However, the core role of advocates is to provide information on legal, housing and financial options and to facilitate access and use of community resources such as refuges/shelters, emergency housing, and psychological services. Advocates can also provide more or less formal counselling and ongoing support. This heterogeneity in the meaning of advocacy will be explored in more depth in the review itself (based on the modes of advocacy offered in individual included studies).

The aims of advocacy are multifaceted and may include helping abused women to access services, the reduction or cessation of abuse, and the improvement of abused women's physical or psychological health. Advocacy may be offered as a stand alone service, but may also be part of a multi‐component intervention. At present, it is not known whether multi‐component interventions are more effective than those comprising a single component. There is some evidence from studies of non‐domestic violence interventions to change clinician behaviour that multi‐component interventions may be more effective than those comprising a single component, although a recent systematic review of guideline dissemination and implementation strategies showed no consistent relationship between numbers of components and effects of multifaceted interventions (Grimshaw 2004).

In this systematic review we examine the effectiveness of single and multiple‐component advocacy interventions with individual women who are still with their partners, as well as those who have already left the abusive relationship. This is because it is known that women who leave violent relationships often continue to be abused, either because the partner pursues them (Mullen 1999; Shalansky 1999) or because the woman enters another abusive relationship (Hegarty 1999; Summerfield 2003). We will include evidence from interventions initiated in any health care setting or from outside of health care if these interventions report data on health outcomes or levels of abuse, and if the findings are transferable and show what can be achieved by health care professionals. This will allow an evaluation of the evidence from various settings, thereby allowing us to ascertain if interventions initiated in healthcare or non‐healthcare settings have differential effects, an issue that is being debated currently amongst domestic violence researchers.