This Week in HIV Research: Vitamin D for CD4? Eh.
Salutations, HIV research consumers. In our roundup of new and noteworthy findings this week, we gain incremental new data that suggest:
- Higher vitamin D levels don't necessarily translate to higher CD4 counts among people on suppressive HIV treatment.
- We have significant obstacles to overcome in helping black men who have sex with men utilize pre-exposure prophylaxis (PrEP) -- and we also have the means to overcome them.
- HIV doesn't worsen aortic stiffness, a key measurement for cardiovascular risk.
- HIV also doesn't worsen health outcomes among those infected with Legionella Pneumonia.
Read on for brief recaps of each of these recently published studies. To beat HIV, you have to follow the science!
Higher Vitamin D Not Associated With Better CD4+ Cell Plateaus
Higher vitamin D levels are not associated with higher CD4+ cell counts in people starting antiretroviral treatment, a study published in AIDS showed. However, levels of 1,25(OH)2D -- a vitamin D metabolite -- prior to starting treatment may serve as a marker of immune response.
Data were based on 560 men whose HIV was suppressed after they started antiretrovirals and who were followed for an average of 8.1 years. 263 of them also had a vitamin D measurement before beginning therapy. While higher rates of another vitamin D metabolite, 25(OH)D, were associated with slightly faster increases in CD4+ cell levels, the CD4+ cell plateau did not differ based on that marker. By contrast, higher 1,25(OH)2D levels before starting HIV treatment were related to lower CD4+ cell plateaus, which could be caused by down-regulated vitamin D receptor activity. Study authors noted that invading pathogens often use this mechanism to evade the host's immune response. However, they advised caution when interpreting this finding since 1,25(OH)2D levels are transient and this marker only modestly predicted CD4+ cell levels.
Study Recommends Measures to Enhance PrEP Effectiveness Among Young African-American MSM
While biomedical failure of PrEP is extremely rare, the same cannot be said for seroconversions among young African-American men who have sex with men (MSM) who have access to PrEP. Interim results from a study of 300 young men in Atlanta, Georgia, which were published in Clinical Infectious Diseases, identified five barriers to PrEP effectiveness: aside from biomedical failure, the results also indicated that poor adherence, discontinuation, contemplation without starting, and refusal all play a role.
Participants were not living with HIV at enrollment, but 14 seroconverted during the study period. Among these, five said they did not want PrEP, five wanted PrEP but never started, two started but then stopped, one did not take enough of the medication, and one may already have had acute HIV when he started PrEP.
Study authors recommended seven measures to prevent PrEP failure in this population: better HIV testing to rule out acute infection before starting PrEP, better adherence monitoring and support, simpler ways to restart PrEP after temporarily discontinuing it, motivational interviews for those thinking about PrEP, health promotion instead of risk mitigation messaging to overcome PrEP refusal, and easier processes for getting the drug covered by insurance or assistance programs.
Aortic Stiffness Tied to Standard Cardiovascular Risk Factors, Not HIV Itself
The severity of aortic stiffness is not associated with HIV, only with traditional cardiovascular risk factors, a study published in Journal of Acquired Immune Deficiency Syndrome showed.
Stiff arteries can predict future cardiovascular events, but this predictor works better when baseline risk is already elevated. Brazilian researchers compared data on aortic stiffness and various health, behavioral and socioeconomic factors among three groups: 644 people living with HIV (PLWH), 105 of their spouses, neighbors or coworkers who are not living with HIV, and 14,873 participants in a medical study among civil servants.
In weighted multivariate models, serostatus did not affect aortic stiffness, but within the PLWH group, traditional cardiovascular risk factors, such as waist-to-hip ratio, did. Fewer years of formal education -- a proxy for socioeconomic position -- were also associated with a higher risk of aortic stiffness, independent of HIV status.
Study authors speculated that access to free health care and antiretroviral medications may mitigate the effects of HIV on cardiovascular health. They called for management of traditional cardiovascular risk factors in people living with HIV, especially among those in disadvantaged socioeconomic groups.
HIV Not Linked to Severity of Community-Acquired Legionella Pneumonia
Community-acquired Legionella pneumonia, or Legionnaires' disease, is not more severe in people living with HIV than in the general population, a Spanish case-control study published in Clinical Infectious Diseases found.
In 2015, Spain reported 916 cases of community-acquired Legionnaires' disease, the second highest in the European Union. The study matched each of 32 PLWH with three people not living with HIV, for a total of 128 participants, all of whom had contracted Legionella pneumonia.
HIV was suppressed in only 54% of HIV-positive participants, yet the study indicated that participants with HIV did not experience a greater length of hospital stay, a higher rate of intensive care unit admission, or a higher rate of death within 30 days of hospitalization relative to HIV-negative participants. Study authors attributed this relative immunological health to the co-trimoxazole prophylaxis given to PLWH with poor immune status, which prevents this pneumonia.
Study authors recommended that PLWH with Legionnaires' disease receive the same medical treatment as those who do not live with HIV, and that this recommendation be included in guidelines for treating community-acquired pneumonia.