Interpersonal violence in NZ is a public health crisis, not just a social one – new research

More than 60% of women in New Zealand have experienced some form of interpersonal violence – an alarming statistic with serious implications for public health.

Interpersonal violence broadly refers to violence between people and includes family or partner violence and community violence (violence among individuals who are not related by family ties but who may know each other).

Our new research finds women who have experienced such violence or abuse are 1.6 times more likely to be hospitalised with cancer. They were nearly three times as likely to be hospitalised for respiratory diseases.

Drawing on a population-based survey of 3,000 men and women, we asked participants about their experiences of various forms of violence, both from partners and non-partners (such as parents, acquaintances or strangers).

Among the 62% of women who reported experiencing some form of violence, 21% said they had faced childhood sexual abuse, 9.2% reported sexual violence by non-partners, and 21% had experienced multiple forms of intimate partner violence, including psychological and economic abuse.

Of the men surveyed, 68.4% reported some experience of interpersonal violence, with the majority (43%) involving physical violence by non-partners – mainly other men.

We then analysed 31 years of hospitalisation data from New Zealand’s National Minimum Dataset. This enabled us to compare the volume and type of hospital admissions for individuals who had reported different forms of violence with those who had not.

Our research not only paints a stark picture of the prevalence of interpersonal violence in New Zealand, but also reveals its clear links to poor health outcomes and added strain on the health system.

Higher rates of hospitalisation

Women who reported experiences of violence were more likely to have been admitted to hospital for multiple health issues.

Between 1988 and 2019, women who had experienced interpersonal violence were almost twice as likely to be hospitalised for pregnancy complications. They were also 1.6 times more likely to be hospitalised for digestive disorders, and 1.5 times more likely to be admitted for injuries – not necessarily as a direct result of violence.

Men who reported experiencing violence were 1.9 times more likely to be hospitalised for injuries. Those who had experienced childhood sexual trauma (7.5% of male participants) were seven times more likely to be hospitalised for nervous system disorders, compared with men who had not experienced such abuse.

While our research establishes strong correlations between interpersonal violence and adverse health outcomes, other researchers have explored why this link exists.

Some point to the effects of “toxic stress”. This is a condition triggered by repeated exposure to fear in situations where fight or flight are not viable options. This stress elevates levels of hormones such as adrenaline and cortisol, both of which can have damaging effects on physical health.

Victims of violence may also attempt to self-medicate through smoking, alcohol or disordered eating. These coping strategies offer temporary relief but carry long-term health risks. Stress-related mental health conditions, such as depression, can suppress the immune system, further increasing vulnerability to illness.

In our health system, behaviours such as smoking or alcohol use are often seen as the root causes of illness, and they certainly play a role. But our research suggests that understanding the trauma behind those behaviours is essential to improving outcomes.

Treating violence as a health issue

One major barrier to addressing interpersonal violence is that it is often framed as a social issue. This can make it difficult for policymakers to prioritise funding in a health system already under strain.

Yet our findings show clearly that interpersonal violence is also a health issue with measurable consequences and costs.

Medical and health education tends to treat violence and trauma as peripheral concerns, with training often added after the fact. There is a pressing need for better understanding among healthcare professionals of the prevalence of trauma and its effects on the body.

Specialist family and sexual violence services must also be adequately funded so that doctors and other health care providers have appropriate referral pathways. And national leadership is needed to affirm that this issue matters.

In a country grappling with the cost of health care, recognising and addressing the trauma behind illness is vital. Supporting healthy relationships and investing in violence prevention will not only keep people safer and healthier – but will ultimately save money.