Reliable and comparable analysis of risks to health is essential for informing efforts to prevent disease and injury. (1) The burden of disease methodology provides a tool for estimating the impact of health problems and risky behaviours across a population, taking into account both illness and premature death. (2)
Previous burden of disease studies have been criticized for failing to provide an accurate and comprehensive picture of the burden of disease and injury among women by excluding some reproductive health conditions associated with significant rates of morbidity, and by omitting to measure the contribution of important risk factors, such as intimate partner violence (IPV), to burden of disease. (3,4)
Increasing evidence indicates that IPV is highly prevalent globally and has serious and long-lasting health consequences. (3,5) These include many disorders for which significant gender disparities in prevalence exist, such as depression, anxiety, eating disorders and reproductive and physical health problems. (6-9) To decrease gender disparities in health outcomes it is essential that the associated risk factors be clearly identified, measured and recognized as a priority for intervention.
Globally, evidence on the prevalence and the health consequences of IPV is growing steadily but, to date, the contribution of IPV to the burden of disease has not been estimated. The overall aim of our study was to estimate the contribution of IPV to the total burden of disease for women living in Victoria, Australia, in 2001. We were able to carry out this study due to the availability of good prevalence data on exposure to IPV and survey data on the health consequences of IPV in Australia, combined with a keen interest among government and nongovernmental organizations in Victoria. The first estimates of burden of disease for Victoria were developed for 1996 and updated to 2001 including IPV as a risk factor for the first time. (10,11)
Using the comparative risk assessment methods, we estimated the disease burden attributable to a particular risk factor by comparing current health status with a theoretical minimum counterfactual status. (1,12) For IPV, the theoretical minimum was defined by the counterfactual status of no past or current exposure to IPV in a population. The attributable fraction of disease burden in the population was determined by the prevalence of exposure to the risk factor and the relative risk of disease occurrence attributed to exposure. We then applied the attributable factions to overall population estimates of mortality or disability burden for each of the health outcomes causally linked with the risk factor.
The national Women's Safety Survey (WSS) constitutes the most recent, comprehensive measurement of the prevalence of IPV in Australia. (13) We used two categories of exposure to IPV--physical or sexual violence by a partner in the past 12 months and physical or sexual violence by a partner more than 12 months ago (Table 1). We opted to use the Australian prevalence as the Victorian age-specific estimates had wide confidence intervals.
We based most of our estimates of the risk of adverse health outcomes on the Australian Longitudinal Study on Women's Health (ALSWH). (14) Three representative cohorts of Australian women aged 18-23, 45-50 and 70-75 years when first surveyed in 1996, have been re-surveyed at three-year intervals. (15) We obtained data from the first two surveys from the study custodians (1996 and 2000 for the youngest cohort; 1996 and 1998 for the middle-aged cohort). The sample sizes for each cohort at first interview were 14 739 and 14 011 for the youngest and middle-aged cohorts, respectively. For the youngest cohort we defined exposure to IPV by combining separate questions on "being pushed, grabbed, shoved, kicked, or hit", "being forced to take part in unwanted sexual activity" and "ever having been in a violent relationship with a partner/spouse". …