Prompt HIV diagnosis and early antiretroviral therapy are especially important for older people, results of a UK study published in Age and Ageing show. There was a 10% one-year mortality rate among people aged 50 plus at the time of their diagnosis, compared to a rate of 3% among younger people. The risk of death was especially high for older people with a CD4 cell count below 200 cells/mm3 at the time of diagnosis and who did not start HIV therapy.
“Late diagnosis is an important determinant of mortality in older adults,” comment the authors.
There has been a general ageing of the HIV-infected population in a number of richer countries. Over half of all patients with AIDS in San Francisco are now aged over 50. Older age is independently associated with immune impairment. Moreover, the diseases of ageing are now an increasingly important cause of illness and death in people with HIV.
A team of UK investigators wanted to determine the effect of age on outcomes in people diagnosed with HIV in England, Wales and Northern Ireland between 2000 and 2009.
They hypothesised that short-term mortality rates – one year after diagnosis – would be higher among older adults than younger adults due to differences in CD4 cell counts at presentation and/or use of antiretroviral therapy.
A total of 63,805 adults were newly diagnosed with HIV between 2000 and 2009. Overall, 5683 (9%) of these diagnoses involved people aged 50 or older, and 217 individuals (4%) were aged 70 or over at the time of their diagnosis. There was some evidence of the general ageing of the HIV population. The number of older adults diagnosed with HIV increased from 299 in 2000 (8% of all diagnoses that year) to 897 (13%) in 2009.
Compared with younger people (49 or younger), older people newly diagnosed were more likely to be white (58 vs 39%, p < 0.01) and heterosexual (31 vs 21%, p < 0.01).
Data on CD4 cell count at diagnosis were available for 75% of patients. The median CD4 cell count for older people was 210 cells/mm3, significantly lower than the 310 cells/mm3 median recorded in younger people. At the time of diagnosis, 48% of older people and 32% of younger individuals had a CD4 cell count below 200 cells/mm3, and were therefore classified as being diagnosed very late.
Consistent with this difference in immune status at diagnosis, older people were significantly more likely than younger (19 vs 9%, p < 0.01) to have presented with an AIDS-defining condition.
There was a total of 2072 deaths after one year, 1515 occurring in older people. The one-year mortality rate was 10% for people aged 50 and over and 3% for younger people (p < 0.01).
The effect of age on mortality risk was present in all HIV-risk groups, but was especially pronounced among gay and other men who have sex with men (MSM). In MSM, individuals aged between 50 and 59 had a one-year mortality risk that was 13 times higher (HR = 13; 95% CI, 8.1-20.0) than people in the 15 to 29 age group. The mortality risk was also significant for older heterosexuals in the 50 to 59 age group (HR = 5.0; 95% CI, 3.3-7.4).
The difference in mortality risk between older and younger people was especially pronounced among those with a CD4 cell count below 200 cells/mm3 at the time of diagnosis (p < 0.01).
Rates of HIV treatment use among severely immune-suppressed patients did not differ between the older and younger age groups (73 vs 74%).
Mortality rates among untreated patients with very late diagnosis were high in both age groups, but especially so among older patients (46 vs 15%).
Starting HIV therapy was beneficial for people diagnosed late. But the benefits were greatest for people in the older age group, reducing the absolute number of deaths by 40%, compared to a 12% reduction in younger people.
Restricting analysis to people with baseline CD4 cell counts between 200 and 350 cells/mm3 showed that a higher proportion of older people than younger individuals started HIV therapy (62 vs 42%). “This may suggest that there was a greater degree of clinical concern in older compared to younger persons,” the researchers suggest. The benefits of treatment were more pronounced for older people, though the magnitude of the benefit was less pronounced than in patients with severe immune suppression.
“Compared with younger adults, 1-year mortality was consistently higher in the older age group, but these differences were significantly larger in individuals presenting very late,” write the authors. “Given the higher mortality, the benefit of ART use in older persons was much greater compared with younger adults.”
They conclude: “Older adults experience especially high rates of mortality within 1 year of diagnosis, largely driven by late diagnosis…wider testing in this population, coupled with prompt treatment, might substantially reduce deaths among HIV-infected persons.”
Davis DHJ et al. Early diagnosis and treatment of HIV infection: magnitude of benefit on short-term mortality is greatest in older adults. Age and Ageing, online edition, doi: 10.1093/ageing/aft052, 2013.