Older people in United States more likely to have AIDS at the time of HIV diagnosis

People with HIV aged 60 and over in the United States are more than twice as likely to have an AIDS-defining illness or a CD4 cell count below 200 compared to under-40s, according to data presented to the recent Conference on Retroviruses and Opportunistic Infections (CROI 2018) in Boston.

Moreover, individuals newly diagnosed with HIV were also more likely to present with several serious non-AIDS-defining illnesses including shingles, bacterial pneumonia, anaemia and thrombocytopenia (low platelet count) than people of a similar age without HIV, so the investigators suggest that the presence of these conditions should trigger HIV testing. The likelihood of presenting with one of these conditions was greater in people diagnosed with HIV compared to HIV-negative controls at all ages, and the prevalence of each grew with age.

The findings were presented by Amy Justice of Veterans Administration Connecticut Healthcare System on behalf of the VACS (Veterans Aging Cohort Study) Project Team.

In 2015, approximately half of HIV-positive individuals in the US were aged 50 years and older. Age at the time of HIV diagnosis is increasing. Surveillance data from the Department of Veterans Affairs – a major provider of HIV care – shows that between 1997 and 1999, new HIV diagnoses peaked in patients aged between 40 and 44 years. By 2015, however, two age peaks were present: 30 to 34 years and 50 to 59 years.

Investigators wanted to see if older age was associated with an increased risk of delayed HIV diagnosis. They also wanted to determine if people newly diagnosed with HIV were more likely than age-matched HIV-negative controls to present with certain non-AIDS-defining conditions – bacterial pneumonia, shingles, anaemia, and low platelet or lymphocyte count. In addition, the researchers assessed the probability of HIV-positive people – stratified by age – presenting with these non-AIDS-related illnesses. If the probability was at least 1%, the investigators recommended that an individual presenting with one of these illnesses should be offered a HIV test.

Data sources were the 3000-person VACS, Centers for Disease Control and Prevention (CDC) HIV surveillance covering 238,311 people and the Nathan Smith HIV Clinic at Yale University (130 incident infections). VACS recruits military veterans at the time of HIV diagnosis in veterans affairs healthcare facilities and matches them with HIV-negative veterans of similar age, year of diagnosis, sex and ethnicity.

Data from VACS showed that between 2010 and 2015, almost half of incident HIV infections involved people aged 50 years and older. At the Nathan Smith Clinic, a quarter of incident infections were in older people and CDC data showed that 18% of new infections were in people aged at least 50 years.

Increasing age was associated with severity of HIV disease at the time of diagnosis, reaching a peak among people aged 60 years and older. Whereas only 21% of under-40s had an AIDS diagnosis (CD4 count < 200 and/or AIDS-defining illness) at the time of HIV diagnosis during the period 2010-2015 in the VACS cohort, 49% of over-60s had an AIDS diagnosis.

People newly diagnosed with HIV were significantly more likely than matched HIV-negative controls to present with bacterial pneunomia. Prevalence among newly diagnosed people increased from 7% in the under 40s to 14% in those aged 60 and older. In contrast, in the HIV-negative control, the prevalence of bacterial pneumonia increased from 1% in the youngest people to just 2% in the older people. The investigators calculated that HIV-positive people in their 50s had a fivefold increase in their risk of bacterial pneumonia, whereas the risk was increased sixfold for people aged 60-plus.

In all age groups, there was greater than 1% probability that people with HIV would also present with bacterial pneumonia.

Newly diagnosed HIV-positive people – regardless of age – were also significantly more likely than their HIV-negative peers to present with shingles (herpes zoster). The proportion of HIV-positive people diagnosed with shingles increased with age, from 3% in the under-40s to 7% in those aged 60 and older. There was an 11% probability that shingles would be present in HIV-positive people aged in their 50s.

Anaemia was also more common in people with HIV and its prevalence likewise increased with age. Up to the age of 59, there was a more than 1% probability that people newly diagnosed with HIV would also present with anaemia. A similar pattern was present for thrombocytopenia.

Based on their findings, the study investigators concluded that:

• Anyone presenting with shingles, thrombocytopenia or bacterial pneumonia should be tested for HIV.

• Anyone under 60 with anaemia or lymphocytopenia should be tested for HIV.

Amy Justice, presenting, cautioned against generalising the applicability of the findings beyond the United States, especially to resource-limited settings. A European study, HIDES 2, looked at the prevalence of HIV in people presenting with indicator conditions in 20 European countries. They found that HIV prevalence was sufficiently high to justify routine testing of everyone presenting with one of 11 indicator conditions. The HIDES 2 study did not look at whether specific conditions were more predictive at an older age.

The VACS investigators therefore conclude that late diagnosis is common among older people with HIV, and that many older newly diagnosed people also presented with certain non-AIDS-defining illnesses less likely to be present in younger people or in people without HIV infection. The presence of these illnesses in most age groups should act as a trigger for HIV testing, the researchers recommend.