Drug toxicity beliefs leading to missed tx

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Beliefs about possible toxic interactions between antiretroviral therapy (ART) and illicit drugs are causing large numbers of people living with HIV who use drugs to intentionally miss doses of their HIV treatment when planning drug use, US investigators report.

The prospective study involved 530 people reporting current drug use in Atlanta. All were taking ART and approximately a third reported missing treatment doses because of beliefs about potential interactions with drugs and alcohol. This planned non-adherence was associated with sub-optimal compliance to treatment and poor control of viral load. “Our results showed that it was common for active drug users with HIV to believe that ART and drugs should not be mixed,” write the authors. “Outcomes from treatment were worse for individuals who said that they do stop taking their medications when using drugs.”

ART requires high levels of adherence and the best results are seen in people who take at least 85% of their doses. Previous research has shown that people with HIV who use drugs have an increased risk of poor adherence to ART because of intoxication. But little is known about whether beliefs about potential interactions between ART and illicit drugs or alcohol are causing drug users to intentionally skip doses of their HIV medication.

To address this gap in the current literature, a team of investigators designed a prospective study involving people living with HIV who were taking HIV treatment and actively using drugs. Urine tests were used to identify patients with active drug use. Computerised self-interviews were then used to gather demographic information. Intentional non-adherence to ART when using illicit drugs was assessed by the question “I stop taking my HIV medications when I will be using drugs to get high.” The same question was asked regarding stopping medication when planning alcohol use. Participants in the study were also asked three questions to determine if they agreed with commonly held beliefs about the risk of adverse outcomes when mixing drugs or alcohol with ART. Pill counts were used to assess actual adherence to ART, and viral load and CD4 count were measured via chart reviews.

The overall mean adherence rate was 83%, with 37% of participants reporting taking fewer than 85% and a quarter of individuals only taking 75% of their doses. Just over a third (35%) of participants reported intentionally stopping their ART if they were using drugs. Women were more likely to intentionally stop their HIV medications than men. Other factors associated with planned non-adherence included lower income, fewer years of education and longer duration of diagnosed HIV infection. Participants intentionally missing ART doses were also more likely to report alcohol abuse and alcohol-related problems.

More than half the individuals with intentional non-adherence endorsed all three beliefs about potential toxicities when mixing ART and drugs. Moreover, 56% of those with intentional non-adherence when using drugs said they would also stop taking their HIV medications when using alcohol.

Participants with intentional non-adherence took 79% of their ART doses. This compared with 85% for other participants. A third of participants who purposefully missed ART doses had a detectable viral load compared to 22% of participants who did not report intentional non-adherence.

“These findings…demonstrate an urgent need to address interactive toxicity beliefs among active drug users who are intentionally non-adherent to ART,” comment the investigators. “Future research should test efficient and effective educational messages to correct interactive toxicity beliefs that contribute to intentional non-adherence and treatment failure.”

Abstract: Drug use poses significant challenges to medical management of HIV infection. While most research has focused on the influence of intoxication on unintentional adherence to HIV treatment, drug use may also lead to intentional non-adherence, particularly when individuals believe that mixing medications with drugs is harmful. This study examined whether interactive toxicity beliefs predict non-adherence to antiretroviral therapy (ART) over a prospective period of adherence monitoring. Men and women living with HIV who screened positive for drug use and were being treated with ART (N=530) completed computerized self-interviews, three prospective unannounced pill counts to measure ART adherence, provided urine specimens for drug screening, and HIV viral load results from medical records. Results showed that 189 (35%) participants indicated that they intentionally miss their ART when they are using drugs. These participants also reported common beliefs regarding the perceived hazards of mixing HIV medications with alcohol and other drugs. Multivariable models that controlled for demographic and health characteristics, as well as frequency of alcohol use, showed that intentional non-adherence predicted poorer ART adherence over the prospective month and also predicted poorer treatment outcomes as indexed by unsuppressed HIV viral load. These findings extend previous research to show that interactive toxicity beliefs and intentional non-adherence play a significant role in medication non-adherence for a substantial number of people living with HIV and should be actively addressed in HIV clinical care.

Aidsmap material
Journal of Acquired Immune Deficiency Syndromes abstract

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