By now, we have all been told incessantly that smoking kills. At the same time, thanks to improvements in treatment, especially antiretroviral therapy, HIV is no longer the death sentence that it used to be. Still, one cannot help but be a little surprised with the finding of a recent study published in the journal Clinical Infectious Diseases - that HIV patients are more likely to die from smoking-related causes than from the disease itself.

The study was conducted in Denmark, where antiretroviral therapy for HIV is available at no cost. In order to pin down data, the researchers used the Danish HIV Cohort Study, which tracks all individuals treated in Danish HIV centers from the year 1995. Individuals were included if they were diagnosed with HIV after the age of 16 and did not take injection drugs. Each of the HIV-positive patients who were included - 2,921 people - were matched with four controls matched for sex and year of birth - 10,642 people - who were enrolled in the Copenhagen General Population Study. In total, the two groups were followed for four years.

The study found that HIV did indeed shorten the lifespan of individuals, though not as significantly as in the past. The expected lifespans of never-smokers shrank by five years. However, more striking was the fact that among the individuals who passed away during the course of the study, only 26 percent died from causes relating to the virus. A whopping 64 percent died from non-AIDS-related causes.

Indeed, the HIV-positive population smoked at a higher rate than the general population. Even still, smoking truncated the lives of the HIV-positive population. While a 35-year-old HIV-positive patient who had never smoked could expect to live to 78.4 years, smokers' lifespans shrank to 62.6 years. Researchers found that, on average, smoking cut 12.3 years off the lives of HIV-positive smokers.

The researchers note that mortality among the controls could have been underestimated. They also said that, although they controlled for a number of factors, the findings could have been muddled by other factors, particularly socioeconomic status. Regardless, they believe that HIV treatments should include anti-smoking measures.