Model shows excellent prognosis for UK gay men with HIV

New UK research provides further evidence of the dramatic impact of antiretroviral therapy on the prognosis of HIV-positive patients. Published in the online edition of AIDS, a simulated model showed that a non-smoking, 30-year-old gay man, whose HIV is diagnosed promptly, could expect to live until he is 78 years of age. A gay man who smoked, but whose HIV was detected early, had a life expectancy of 75 years.

The model also showed that late diagnosis of HIV cut life expectancy. Nevertheless, it showed the clear benefits of HIV therapy in these circumstances. A gay man whose HIV was detected when his CD4 cell count was just 140 cells/mm³ could still expect to live until he was 71.5 years old.

“Predicted life expectancy in people with HIV is high in settings with access to multiple antiretroviral drugs,” comment the investigators. “Delays in diagnosis pose the greatest risk of excess mortality for people with HIV.”

It is now well established that modern antiretroviral therapy significantly improves the life expectancy of patients with HIV. However, investigators from the UK were concerned that studies attempting to quantify prognosis may have underestimated the benefits of treatment because they did not take into account improvements in HIV therapy and care.

They therefore developed their own prognostic model. It was based on 10,000 theoretical gay men whose HIV was diagnosed in 2010. They selected this group because factors other than HIV impact on the prognosis of the other main groups affected by HIV in the UK.

Rates of HIV testing currently observed in UK gay men were incorporated into the model. These show that HIV is generally detected early, with median CD4 cell count at the time of diagnosis being 410 cells/mm³. It assumed that the patients had fully drug-sensitive HIV, had a 40% chance of being a smoker for life, were not co-infected with hepatitis and were never lost to follow-up. HIV treatment was started when the patients’ CD4 cell count fell to 350 cells/mm³ and the patients were fully adherent to this.

Higher rates of some non-HIV-related illnesses have been observed in patients with HIV. Therefore, the investigators assumed that their simulated patients were 50% more likely to die of such diseases than individuals in the general population.

The same scenario was considered for patients whose HIV was diagnosed late.

In ideal conditions, with timely diagnosis of HIV, the life expectancy of patients was 75 years (range, 63 to 83 years). This increased to 78 years if the patient did not smoke (range, 66 to 86 years).

The model predicted that 57% of men would be diagnosed within three years of infection with HIV, increasing to 78% after five years and 97% after ten years. The median CD4 cell count at the time of diagnosis was 432 cells/mm³ and 98% of patients were projected to start therapy within six years of diagnosis.

In the late diagnosis model, median CD4 cell count at the time of diagnosis was 140 cells/mm³ and projected life expectancy was 71.5 years (range, 52 to 82 years). It assumed that only 23% of patients would be diagnosed within three years of infection with HIV, increasing to 37% after five years and 74% after ten years.

“This low rate of diagnosis resulted in a higher risk of death by ten years of infection,” write the investigators. This was 13% compared to just 5% in the early diagnosis scenario.

In 2009, the anticipated life expectancy of an HIV-negative man in the general UK population was 82 years. Therefore the prognosis of patients with HIV was between four and eleven years shorter.

“This excess mortality is similar to that of other chronic diseases such as diabetes,” comment the researchers.

They note that the life expectancy predicted by their simulation is somewhat better than that suggested by a number of other studies. The researchers believe that this is because they were able to take into account recent improvements in treatment and care, especially the introduction of easy-to-take, potent and relatively safe drugs.

However, they conclude, “there is still room for improvement such that life expectancy reaches the same as that of the non-infected population.”

Nakagawa F et al. Projected life expectancy of people with HIV according to timing of diagnosis. AIDS 25, online edition, doi: 10.1097/QAD.0bo13e32834dcec9, 2011.