Smoking doubles risk of death for patients taking HIV therapy

Smoking doubles the mortality risk for people with HIV taking antiretroviral therapy, a study published in AIDS shows. Smokers had an increased risk of death from cardiovascular disease (CVD) and non-AIDS-related cancers, and the life expectancy of a 35-year-old man with HIV was reduced by almost eight years due to smoking.

“Smoking was associated with a two-fold increase in mortality,” comment the authors. “More than a third of all non-AIDS related malignant deaths were from lung cancer and all deaths from lung cancer were in smokers.”

The benefits of not smoking were clear. HIV-positive non-smokers who were doing well on antiretroviral therapy had a similar life expectancy to non-smokers in the general population.

With the right treatment and care, people living with HIV can have a normal life expectancy. However, mortality rates remain higher among people with HIV compared to the background population. The reasons for this are unclear, but important causes of death among people with HIV now include smoking-related diseases such as heart and lung complaints and non-AIDS-related malignancies.

Investigators therefore wanted to determine the association between smoking and mortality risk among people taking HIV therapy.

They analysed information relating to approximately 18,000 people in Europe and North America who started HIV therapy between 1996 and 2008. All the patients were followed for at least a year after starting therapy, and collectively they contributed approximately 80,000 person-years of follow-up. Most of the patients (60%) were smokers.

The all-cause mortality rate was 7.9 per 1000 person-years for smokers and 4.2 per 1000 person-years for non-smokers.

Overall, smokers had twice the mortality risk compared to non-smokers (mortality rate ratio [MRR] = 1.94; 95% CI, 1.56-2.41).

Detailed data on smoking history were available for approximately 8500 people and these showed that, compared to people who had never smoked, mortality risk was significantly increased for current smokers (MRR = 1.70) but not people who had stopped smoking (MRR = 0.92).

“The finding of a markedly lower risk of death among previous compared with current smokers points towards potential benefits of including smoking cessation interventions in HIV care,” write the authors.

Almost three-quarters (71%) of recorded deaths were non-AIDS related. Rates of non-AIDS-related death were significantly higher among smokers (MRR = 4.6 per 1000 person-years) compared to non-smokers (MRR = 2.6 per 1000 person-years).

Rates of cardiovascular disease, non-AIDS cancers and liver disease were all significantly higher among smokers than non-smokers.

Lung cancer accounted for a third of all non-AIDS-related malignancies and all deaths from this cancer involved smokers. Moreover, almost all (96%) the other deaths caused by cancers potentially associated with smoking occurred among smokers.

The life expectancy of a 35-year-old HIV-positive man who smoked was on average eight years shorter than that of an HIV-positive non-smoker.

Prognosis was affected by both smoking status and viral load. A male 35-year-old HIV-positive non-smoker with an undetectable viral load had an identical life expectancy to a 35-year-old male in the background population.

The impact of smoking on excess mortality risk increased significantly with age (MMR at age 35 = 0.6; MMR at age 65 = 43.6).

“We conclude that HIV-infected individuals with long-term engagement in care may lose more life years through smoking and associated lifestyle factors than through HIV,” conclude the investigators. “Interventions for smoking cessation should be prioritized.”