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Simple risk score can identify gay men who may have acute HIV infection
Roger Pebody, 2017-03-07 07:10:00
Seven simple questions about symptoms and risk factors
identified three-quarters of gay men in Amsterdam who have acute (very recent)
HIV infection, according to a study presented at the Conference on Retroviruses and
Opportunistic Infections (CROI 2017) in Seattle last month. Using this risk
score could identify gay men requiring HIV RNA testing (which can detect acute
infections) in addition to HIV antibody testing.
Promptly diagnosing people who have acute HIV infection is
important from both an individual and a public health perspective. But, diagnosis is
challenging because the symptoms of acute infection can be caused by other common
health problems like the flu and the most commonly used tests cannot detect the
most recent infections. The alternative tests for HIV RNA are expensive and there
are no clear guidelines on when to use them.
Researchers analysed data from 1562 men who have sex with
men enrolled in the Amsterdam Cohort Studies. At 17,271 study visits men tested
HIV-negative, while at 175 visits they had recently acquired HIV. The men had
provided data on their health (including whether they had experienced 14
symptoms associated with HIV seroconversion) and sexual behaviour.
The researchers examined the factors associated with
acquiring HIV. Two multivariable logistic regression models were constructed:
one including only symptoms and one combining symptoms with other risk factors,
using generalised estimating equations.
Several risk scores were tested. The optimal one included
both symptoms and risk factors, assessed over the previous six months:
- Fever 1.6
- Swollen lymph nodes 1.5
- Oral thrush 1.7
- Weight loss 0.9
- Receptive anal sex without a condom 1.1
- More than five sexual partners 0.9
- Gonorrhoea 1.6
The cut-off for the score is 1.5, meaning that any man with
one of the first three symptoms or gonorrhoea would be recommended to be tested
for acute HIV. Equally, a combination of any two (or more) factors would be an
indication that further testing is appropriate.
Using this risk score with members of the Amsterdam Cohort
would indicate that 24% should be tested for HIV RNA. In terms of sensitivity,
the risk score identified 76% of men with acute infection.
Validating the risk score with a different cohort, the Multicenter
AIDS Cohort Study (MACS) from the United States, 12% of participants would be
recommended for further testing, but the risk score was less sensitive – 56% of
men with acute infection would be identified.
The area under the curve (AUC) was 0.82 for the Amsterdam
Cohort and 0.78 for MACS.
Different score cut-offs could be used, depending on the
local context, local prevalence
of acute infection, cost of a false positive and cost of a false negative. A
lower cut-off would result in fewer cases of acute infection being missed but a
larger proportion of men requiring testing.