Smoking is more deadly for HIV positive patients than the virus itself, according to a study published online by the journal Clinical Infectious Diseases.

Researchers looked at nearly 3,000 H.I.V patients treated in Denmark from 1995 to 2010.

The study compared Danish HIV patients with a pool of 10,642 average patients of the same age and sex.

HIV appeared to make smoking much more deadly. The risk of early death from cancer or heart disease was much higher among infected smokers than among non-infected ones.