One third of women around the world have experienced physical or sexual violence at the hands of their intimate partners with consequences from post-traumatic stress disorder, anxiety, and depression, to sexually transmitted diseases, including HIV. Now, in a new study in 29 low-income and middle-income countries, researchers at Columbia University's Mailman School of Public Health have identified yet another serious health risk associated with intimate partner violence (IPV): smoking.

The researchers examined the association between IPV and smoking among 231,892 women aged 15-29, using information collected in the Demographic and Health Surveys. Intimate partner violence is a serious problem in low- and middle-income countries. Reports of IPV in their study ranged from 9 to 63%. Employing a meta-analysis of country-level data that accounted for confounding factors like age, education, and household wealth, they found a 58% increased risk for smoking among the women who experienced IPV.

Women are thought to smoke tobacco to self-medicate to cope with stress from IPV. Many may be unaware of the serious health risks; tobacco kills half of its users, according to the World Health Organization.

"A recent WHO report on IPV recommended that there is a clear need to scale-up efforts to both prevent IPV from happening in the first place and to provide necessary services for women experiencing IPV," says senior author Peter A. Muennig, MD, MPH, associate professor of Health Policy and Management at Columbia's Mailman School of Public Health.

The study points to a specific need for investments to help IPV victims avoid tobacco, adds first author Rishi Caleyachetty, MBBS, PhD, an epidemiologist on a Fulbright Scholarship at Columbia's Mailman School of Public Health when he wrote the paper. "Information about the consequences of smoking, motivation to quit smoking and smoking-cessation treatments could be incorporated into IPV treatment by healthcare providers who routinely interact with IPV victims," Dr. Caleyachetty says.

Any intervention to lower smoking would very likely also improve their overall health. A 2013 report by the World Health Organization suggested a link between IPV and chronic conditions, including cardiovascular disease. "Smoking is associated with cardiovascular disease, and therefore may explain part of the association between exposure to IPV and cardiovascular disease," says Dr. Caleyachetty. "However, to my knowledge this has not been extensively examined."

The new study focused on low- and middle-income countries, where little research into the IPV-tobacco link has been done. However, the researchers say their results likely mean that the phenomenon is a global one. They cite among other papers, a 2008 study by Hee-Jin Jun et al that showed increased risk in American women.

IPV and smoking may have both been underreported in the current study, which could mean that the association between the two is stronger. A temporal relationship (e.g. IPV causes smoking) couldn't be determined since the data was collected at only one point in time. Research following a group of women over time would be necessary to strengthen the evidence.