New research published in The Lancet reports that 1 in 14 women (7.2%) have been sexually assaulted at least once in their lives by someone other than an intimate partner.

Several recent highly publicized incidences of the rape and murder of young women in India and South Africa have put an international focus on the issue of sexual violence against women. These are extreme cases, but the authors of the report warn that “although it is tempting to view these events as isolated, they should be seen as part of a larger, daily reality of sexual violence against women.”

The historical and media perception of rape has largely focused on the idea of sexual assault as a crime committed by strangers. In truth, the research over the past decade into “intimate-partner violence” has highlighted that a large proportion of sexual violence occurs within relationships.

Intimate-partner violence often finds expression in long-term controlling behavior and could cause significant psychological problems, whereas “non-partner sexual violence” is likely to be more violent and involve weapons or injury, according to a World Health Organization study.

“Irrespective of whether sexual violence is perpetrated by partners or non-partners, it is generally traumatic for the victim,” the authors remind, “although the pattern, degree, and effect of violence might differ dependent on the perpetrator.”

The authors believe improved understanding of prevalence across different countries and regions is “a fundamental first step in the development of effective responses to non-partner sexual violence.” But the global extent of sexual violence has been difficult to measure.

With this study, the authors conducted a systematic review of the available evidence on non-partner sexual violence in order to estimate prevalence.

The researchers looked at 77 studies from 56 countries conducted between 1998 and 2011, which compiled data on sexual assaults against women aged 15 years and older. The results of the systematic review displayed a wide variation in estimates of sexual violence across regions.

The regions with the highest estimates of sexual violence were:

  • Central sub-Saharan Africa (21%; Democratic Republic of Congo)
  • Southern sub-Saharan Africa (17.4%; Namibia, South Africa, Zimbabwe)
  • Australasia (16.4%; New Zealand and Australia).

The regions with the lowest estimates of sexual violence were:

  • North Africa/Middle East (4.5%; Turkey)
  • South Asia (3.3%; India, Bangladesh).

The systematic review found that, worldwide, 1 in 14 or 7.2% of women older than 15 years had reported ever experiencing non-partner sexual violence. This shows that sexual violence is widespread and – in some regions – endemic. In four regions the prevalence rate was higher than 15%.

The authors think their data probably underestimates the prevalence of sexual violence. This is because the stigma and blame attached to sexual violence is known to lead to under-reporting. The researchers think this might be why eight regions in the study only had data from one country and many countries had no data at all.

“Despite the limitations of the existing data,” say the authors in their conclusion, “we found that sexual violence is a common experience for women. Sexual violence, irrespective of the perpetrator, violates the human rights of victims and has a profound and enduring effect on their lives.”

Previous systematic reviews examining the health consequences of non-partner sexual violence have found associations with depression, anxiety and alcohol abuse. Victims of sexual violence also show an increased risk for later exposure to other kinds of violence.

Kathryn Yount, from Emory University, Atlanta, GA, describes the study as “a landmark in its scale and rigor,” adding that the prevalences estimated by the study are “unacceptably high on public health and human rights grounds.”

She hopes that the study will:

“[…] spur timely and systematic discussions about the use of standard definitions and improved research tools and data collection methods to improve disclosure of a highly stigmatized violation.

The data confirm that non-partner sexual violence is neither rare nor geographically isolated and, thus, that existing laws and systems of accountability remain inadequate. Effective responses will require widespread legal and institutional change.”

In 2013, Medical News Today reported on a study suggesting that nearly 10% of youths have instigated sexual violence.