Much of the increased mortality seen in patients with HIV in the past decade – outside of antiviral drugs – can be attributed to a reduction in smoking, according to a study in Denmark.

According to Aidsmap, the online edition of Clinical Infectious Diseases reported that smoking has had a bigger impact on the prognosis of HIV-positive patients than HIV-related factors.

In a survey of 2,921 HIV-positive adults, the authors calculated that a non-smoker aged 35 had a life expectancy of 78 years.

This compared to a life expectancy of 69 for former smokers, and a life expectancy of just 63 for current smokers.

The risk of non-HIV-related death was five-times higher for current smokers compared to HIV patients who had never smoked.

HIV patients who were current smokers also had a four-fold increase in their risk of all-cause mortality.

Previous studies have shown that HIV-positive individuals are more likely to smoke than their HIV-negative peers.

According to the British Heart Foundation, over a third of gay men in the UK smoke, compared with the national average of 21%.

The authors of the Danish research believe their findings have important implications for HIV care, showing the importance of smoking cessation counselling and support.

“The loss of life-years associated with smoking was larger than that associated with HIV,” said the study. “HIV-infected smokers with long-term engagement in care lose more life-years to smoking than HIV.”

Illnesses that are potentially related to smoking, such as cardiovascular disease and cancers, are being seen with increased frequency in those living with the virus.