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  Conference on Retroviruses
and Opportunistic Infections
Seattle, Washington
March 4-7, 2019
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One third of elderly HIV group takes complex
regimens and risks drug interactions
  Conference on Retroviruses and Opportunistic Infections (CROI), March 4-7, 2019, Seattle
Mark Mascolini
One third of elderly people in a 1034-person Swiss HIV Cohort Study (SHCS) analysis took complex antiretroviral regimens that threaten dangerous drug-drug interactions (DDIs) [1]. Almost half of this group took 5 or more non-HIV drugs. But the rate of potential DDIs is falling in the overall cohort, perhaps because of increasing integrase inhibitor use and higher prescriber awareness.
As HIV populations age, they face growing risks of multiple non-HIV drug use (polypharmacy), DDIs, and inappropriate prescriptions. SHCS investigators undertook this study to track types of antiretroviral therapy (ART) taken, cardiovascular and central nervous system (CNS) drug use, and potential DDIs and inappropriate drugs in cohort member younger than 65 and those 65 or older.
Researchers at two SHCS centers contacted cohort members and asked them to record all current medications including nonprescription drugs. They defined polypharmacy as taking 5 or more non-HIV drugs, and inappropriate drugs for elderly people were anticholinergics and benzodiazepines. The investigators used an online tool (www.hiv-druginteractions.org) to spot potentially dangerous DDIs between ART and non-HIV drugs.
This analysis included 1034 HIV-positive people with a median age of 51 years; 131 people (13%) were 65 or older. Two thirds of participants (68%) were men, 96% had a viral load below 50 copies, and median CD4 count stood at 683.
Similar proportions of people older or younger than 65 took an integrase inhibitor (49% and 48%), but a higher proportion of the older group (31% versus 23%) took a complex regimen including an integrase inhibitor plus a protease inhibitor (PI), an integrase inhibitor plus a PI and a nonnucleoside, or a PI plus a nonnucleoside.
The SHCS team identified polypharmacy in 167 people (16%). Polypharmacy prevalence rose steadily with each age group analyzed, reaching about 25% in the 55-to-64 group and affecting 46% in the 65-or-older group. The most frequently prescribed non-HIV medications in these two oldest age groups were lipid drugs, renin-angiotensin agents, and antithrombotics.
Inappropriate medications were noted in 14% of elderly patients. Benzodiazepines were the most frequent offender. The anticholinergic antihistamine hydroxyzine represented one third of all drugs with an anticholinergic risk scale score of 3 or higher.
The researchers stressed that the complex antiretroviral regimens taken by one third of people 65 or older have a high potential for causing DDIs. Potential DDIs with cardiovascular drugs proved more common in elderly participants, whereas CNS drugs posed the greatest DDI risk in younger people. But the researchers spotted no deleterious DDIs because physicians have appropriately adjusted drug doses of potential DDI perpetrators. They also found that the rate of potential DDIs has dropped since a similar SHCS analysis in 2010 [2].
Because of a higher polypharmacy rate and additional risk of inappropriate drug use in older people with HIV, the SHCS team stressed the need for continuing caution when prescribing to this group. They called for "education on geriatric medicine principles and periodic medications review . . . to limit the risk of prescribing errors in this vulnerable, growing population."
1. Courlet P, Marzolini C, Cavassini M, et al. Polypharmacy, inappropriate drugs, and drug-drug interactions in HIV-infected elderly. Conference on Retroviruses and Opportunistic Infections (CROI). March 4-7, 2019. Seattle. Abstract 466. 2. Marzolini C, Elzi L, Gibbons S, et al. Prevalence of comedications and effect of potential drug-drug interactions in the Swiss HIV Cohort Study. Antivir Ther. 2010;15:413-23.