This Week in HIV Research: Sex, Drugs, and Broken Bones

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Most weeks, we try to find a common theme that threads through the four studies we select as our peer-reviewed HIV-related research to highlight in brief. This week, however, we're going the opposite route: We've picked a potpourri of topics with at-best casual connections to one another -- with the possible exception of the first two, we suppose. On tap this week:

  • Men who have sex with men (MSM) in the U.S. are reporting more casual sex partners than they did in the prior decade.
  • MSM may underestimate the value of pre-exposure prophylaxis (PrEP) when their levels of sexual activity or social connectedness are relatively low.
  • Proteinuria is a risk factor for fragility fractures, and appears to be quite common among people with HIV.
  • Cannabis use may have a complex relationship with inflammation in people living with HIV (PLWH).

Hop from topic to topic with us as we take a deeper look at each. To beat HIV, you have to follow the science!

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More MSM Now Report Multiple Casual Sex Partners

Between 2008 and 2014, the proportion of MSM who had casual partners in addition to their main partners increased, a study published in Journal of Acquired Immune Deficiency Syndrome showed.

Using data from the Centers for Disease Control and Prevention’s National HIV Behavioral Surveillance system, researchers analyzed responses from 28,061 men who were asked about their sexual partners and behavior during the prior year. The mean number of sex partners increased from 7.1 in 2008 to 7.7 in 2014, while the mean number of main partners remained stable.

The increase was attributed to a greater proportion of participants reporting two or more casual partners in addition to one or more main partner(s) during later survey rounds. That trend, in turn, appeared to be driven by online dating: When data were stratified by that variable, significant increases occurred only among those reporting at least weekly use of the Internet to meet other men.

Study authors called for more research into trends in Internet use and associated risk behaviors, as well as whether such relationships are concurrent or serial. "In light of these behavioral trends, prevention efforts that use knowledge about partners are needed," they concluded.

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Low Risk Behavior Frequency May Lead MSM to Underestimate PrEP's Value

MSM who meet PrEP eligibility criteria are less likely to start the drug if they estimate their levels of sexual activity to be relatively low or they report less social connectedness, an Australian study published in the Journal of Acquired Immune Deficiency Syndromes showed.

The Following Lives Undergoing Change (Flux) study surveyed men online over time. Among 1,257 participants, 29% meet PrEP criteria at baseline and 44% did so at some point during the 24-month study period. Thirty percent of those eligible for PrEP at baseline started that prevention method.

Those who did not take biomedical HIV prevention reported less consistent and less frequent risk behaviors than participants who began PrEP. Men may not initiate PrEP if they believe their risk of HIV acquisition to be sufficiently low -- an assessment that may or may not be reasonable, depending on current number of partners and sexual practices.

Men with more social connections in the gay community were more likely to begin PrEP, showing the importance of peer networks for disseminating HIV prevention information and increasing PrEP uptake, they noted.

Australian PrEP guidelines do not consider the frequency of certain behaviors, only whether or not a person reports them. A more nuanced application of these criteria may be necessary, study authors opined.

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Proteinuria More Common Among MSM With HIV; Fragility Fractures More Likely

Proteinuria is associated with fragility fractures both in men living with HIV and HIV-uninfected men, but is more common among PLWH, a study published in the Journal of Acquired Immune Deficiency Syndromes found.

Researchers analyzed data on urine protein and bone fracture histories from 947 PLWH and 969 HIV-negative men, all MSM ≥ 40 years old enrolled in the Multicenter AIDS Cohort Study (MACS). The adjusted hazard ratio for fractures in those with proteinuria compared to no protein in urine was 2.29, independent of serostatus. Proteinuria prevalence was 29% among participants living with HIV, nearly five times the 5% prevalence found among HIV-negative participants.

A surprise finding was the association of moderate to high alcohol intake with lower fracture risk. After further investigation, study authors concluded that people with comorbidities were more likely to stop drinking, so this result may reflect the fact that only comparatively healthy participants continued to consume alcohol to excess.

No association was found between fractures and estimated globular filtration rate, a marker of kidney function . However, few men in this cohort had impaired kidney function, limiting the relevance of the findings.

"These data highlight the importance of osteoporosis screening and treatment in PLWH with proteinuria," study authors concluded. They called for additional research into the underlying mechanisms behind this finding.

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Study Explores Inflammatory Profile of Cannabis, Cocaine in HIV

In PLWH, using cannabis induced an anti-inflammatory profile, while using cocaine or a combination of cannabis and cocaine had more mixed results, a small Brazilian study published in AIDS found.

Blood specimens from 62 PLWH and 17 HIV-negative controls were analyzed. Twenty PLWH served as controls, 21 smoked cannabis, 8 inhaled or smoked cocaine, and 13 used both drugs. All PLWH were on antiretroviral therapy.

Using one or both substances was associated with increased levels of sCD14, a marker of monocyte activation, compared to not using either of the two drugs. Higher levels of that marker have been previously linked to HIV disease progression and mortality.

An analysis of monocyte subsets suggested that, despite the sCD14 increase, cannabis is a negative regulator of immune response, although it is not known how much this may impair the body's response to HIV. Cocaine appears to decrease monocyte activation and augment inflammation.

Study authors hypothesized that some of the effects observed may be linked to gut bacteria being translocated at a higher rate. "Further studies are required to better understand the action of these drugs in HIV infection," they concluded.