Time to promote earlier HIV diagnosis among older adults living with HIV in South Africa

Age in antiretroviral therapy programmes in South Africa: a retrospective, multicentre, observational cohort study.

Cornell M, Johnson LF, Schomaker M, Tanser F, Maskew M, Wood R, Prozesky H, Giddy J, Stinson K, Egger M, Boulle A, Myer L, International Epidemiologic Databases to Evaluate A-SAC. Lancet HIV. 2015 Sep;2(9):e368-75. doi: 10.1016/S2352-3018(15)00113-7. Epub 2015 Aug 4.

Background: As access to antiretroviral therapy (ART) expands, increasing numbers of older patients will start treatment and need specialised long-term care. However, the effect of age in ART programmes in resource-constrained settings is poorly understood. The HIV epidemic is ageing rapidly and South Africa has one of the highest HIV population prevalences worldwide. We explored the effect of age on mortality of patients on ART in South Africa and whether this effect is mediated by baseline immunological status.

Methods: In this retrospective cohort analysis, we studied HIV-positive patients aged 16-80 years who started ART for the first time in six large South African cohorts of the International Epidemiologic Databases to Evaluate AIDS-Southern Africa collaboration, in KwaZulu-Natal, Gauteng, and Western Cape (two primary care clinics, three hospitals, and a large rural cohort). The primary outcome was mortality. We ascertained patients' vital status through linkage to the National Population Register. We used inverse probability weighting to correct mortality for loss to follow-up. We estimated mortality using Cox's proportional hazards and competing risks regression. We tested the interaction between baseline CD4 cell count and age.

Findings: Between Jan 1, 2004, and Dec 31, 2013, 84 078 eligible adults started ART. Of these, we followed up 83 566 patients for 174 640 patient-years. 8% (1817 of 23 258) of patients aged 16-29 years died compared with 19% (93 of 492) of patients aged 65 years or older. The age adjusted mortality hazard ratio was 2.52 (95% CI 2.01-3.17) for people aged 65 years or older compared with those 16-29 years of age. In patients starting ART with a CD4 count of less than 50 cells per µL, the adjusted mortality hazard ratio was 2.52 (2.04-3.11) for people aged 50 years or older compared with those 16-39 years old. Mortality was highest in patients with CD4 counts of less than 50 cells per µL, and 15% (1103 of 7295) of all patients aged 50 years or older starting ART were in this group. The proportion of patients aged 50 years or older enrolling in ART increased with successive years, from 6% (290 of 4999) in 2004 to 10% (961 of 9657) in 2012-13, comprising 9% of total enrolment (7295 of 83 566). At the end of the study, 6304 (14%) of 44 909 patients still alive and in care were aged 50 years or older.

Interpretation: Health services need reorientation towards HIV diagnosis and starting of ART in older individuals. Policies are needed for long-term care of older people with HIV.

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Editor’s notes: This article reports on a retrospective cohort analysis that examined the effect of age on mortality of people starting antiretroviral therapy (ART) in South Africa. Previous studies already illustrated higher mortality and lower risk of loss to follow-up in older people compared to younger adults on ART. Older people on ART also experience poorer immunological recovery on ART.

The investigators used data from six South African cohorts. Their dataset, with more than 80 000 people who started ART between 2004 and 2013, included much larger numbers of older adults than previously reported, particularly in low and middle income countries. This enabled the investigators to look at baseline characteristics of older people at ART initiation, such as CD4 count, and their association with mortality, which may not have been possible in analysis of single cohorts.

The authors found increasing proportions of people older than 50 years, initiating ART in successive years, from 6% in 2004 to 10% in 2013. They affirmed findings from previous studies that mortality increased with age at ART initiation, while loss to follow-up did not. They also affirmed that immunological recovery was diminished in older people, with smaller gains in CD4 cell count at older age than at younger ages.

Interestingly they found that the effect of age on mortality was strongest among individuals with the lowest baseline CD4 cell counts (lower than 50 cells/mm3). Older people were 2.5 times more likely to die compared to younger people in this group. In people with higher CD4 cell counts (more than 200 cells/mm3) the effect of age at ART initiation was less strong. Moreover some 15% of people aged 50 years or older started ART at CD4 cell counts of less than 50 cells /mm3, and should thus be prioritised as a key group of people requiring additional attention in ART programmes.

The lack of HIV prevention and testing strategies for older people may be one of the reasons for delayed diagnosis and late ART initiation. In addition, health care workers are less likely to consider an HIV diagnosis in older people.

The authors suggest that some of these older people may be long-term survivors despite the absence of ART, and further research into this could be valuable.

Africa
South Africa
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