Tobacco use, including snuff, chewing and smoking, is more than twice as likely to cause death in HIV patients as the infection itself, scientists warned today.

Researchers at the University of York in the UK said that tobacco use is emerging as a 'silent killer' for HIV patients and is more common among HIV positive people than HIV negative individuals.

The study, published in The Lancet Global Health journal, aims to raise further awareness of the dangers associated with tobacco use among people living with HIV.

This follows recent research which showed that young people on HIV drugs have a near-normal life expectancy due to improved treatments for the disease, researchers said.

Medical advances in HIV mean that HIV patients may only lose about five years of life due to HIV. However, if they smoke, they may lose as much as 12 years of life.

This means that tobacco use is more than twice as likely to cause death in HIV patients as the HIV infection itself, said researchers.

The study showed that in low and middle-income countries, particularly in the African region, HIV-positive men are 41 per cent, and HIV-positive women 36 per cent, more likely to use tobacco, including snuff, chewing and smoking tobacco, than their HIV-negative counterpart.

For tobacco smoking only, HIV-positive men were 46 per cent more likely and women 90 per cent more likely to smoke than individuals who did not have HIV.

However, the proportion of HIV positive men who smoke was much higher at 24.4 per cent, than that of HIV positive women who smoke at 1.3 per cent.

"In high-income settings, the proportion of HIV-positive individuals who smoke has also been shown to be higher than among HIV-negative individuals of the same age and sex," said Noreen Mdege, from the York's Department of Health Sciences.

"Our findings confirm that this trend is the same for low and middle-income countries, where the burden of HIV and tobacco-related illnesses is greatest.

"We still don't know for certain the reasons why tobacco use should be significantly higher in HIV patients; more research is needed to understand why," said Mdege.