This Week in HIV Research: Increased Muscle Area After Starting Treatment Likely Due to Fat Accumulation

This week, a study finds that increased muscle area after starting HIV treatment may be due to fat accumulation within the muscle rather than new muscle formation. Another study finds that greater social network clustering among people who inject drugs in the Philippines may contribute to the higher rates of HIV transmission. And partners of people newly diagnosed with HIV were more likely to get tested after receiving assisted partner notifications compared to passive testing referrals. To beat HIV, you have to follow the science!

Increase in Muscle Area After HIV Treatment Likely Due to Fat Accumulation in Muscles

The previously-established increase in muscle area after starting antiretroviral therapy is more likely due to greater fat accumulation within the muscle than actual muscle forming, researchers reported in AIDS.

The researchers analyzed computed tomography scans of trunk muscles in people participating in a clinical trial of HIV medications. Most of the 235 participants in this study were men, and almost a third were African American. All had never taken antiretrovirals before. Over 96 weeks of therapy, total muscle area increased slightly, but the lean muscle component of that area did not. Overall muscle density decreased, in fact. Study authors therefore concluded that the increase in muscle area was driven by greater fat content in the muscles.

Studies among older adults have shown that lower density of trunk muscles impacts physical function and the likelihood of falls. The greater fat content was particularly pronounced in women. Contrary to previous studies, African-American men had more lean muscle mass than men of other races. However, study authors noted that the exploratory analysis did not account for physical activity, nutrition or other medications, all of which might explain this difference.

Greater Network Clustering Associated With Higher HIV Transmission Rates in the Philippines

Greater social network clustering among people who inject drugs appears to be associated with higher rates of HIV transmissions, a study of two Philippine cities published in Journal of Acquired Immune Deficiency Syndrome found.

HIV prevalence in the city of Cebu rose quickly over three years to 54% in 2011 and continued at a high rate through 2013, while in nearby Mandaue prevalence was low through 2011 and then rose to 38% by 2013. Researchers used respondent-driven sampling to estimate network clustering in both places. Age, education and needle-sharing levels were similar in the two locations, but network clustering was much higher in Cebu. This might explain the higher HIV rates and more rapid spread of the virus in that location, study authors concluded.

"This [study] is the first to apply estimators of network clustering to empirical respondent-driven samples, and it offers suggestive evidence that researchers should pay greater attention to network structure's role in HIV transmission dynamics," the authors concluded.

Assisted Partner Notification Significantly Increases HIV Testing Uptake

HIV testing among partners of people diagnosed with HIV was 1.5 times higher with assisted partner notification compared to passive testing referrals, an analysis conducted by the World Health Organization (WHO) and published in AIDS showed.

Assisted partner notification refers to when a trained provider helps a person living with HIV, with their consent, disclose their status to sexual partners, either on their behalf or anonymously. The provider then offers testing to the notified partner. Passive partner notification refers to when a trained provider encourages a person living with HIV to disclose their status to partners, but there is no formal notification or follow-up.

Researchers used data on more than 5,000 participants in 10 studies across eight countries. The higher testing rates among sexual or injection partners of people living with HIV who were offered assistance in telling their partners also resulted in a 1.5-fold increase in HIV diagnoses among these partners. However, passive referral also increased the number of partners tested compared to no referral, and some studies showed similar levels of HIV testing uptake between assisted notification and passive referral groups. The trials analyzed were conducted at various time points, including prior to the advent of triple antiretroviral therapy, which may explain some of these differences.

"Although programme implementers should be sensitive to the potential for harm arising from disclosure of HIV status and assisted partner notification, this should be balanced against the benefit of diagnosing HIV infection and linking people to treatment," the authors noted.