HIV-positive patients who are taking a large number of medications for the treatment of non-HIV-related conditions are at increased risk of stopping or changing their antiretroviral therapy (ART), according to Canadian research published in AIDS Patient Care and STDs. A third of patients were taking five or more non-HIV-related medications (polypharmacy) and 37% of patients with polypharmacy stopped/changed HIV therapy compared to 30% of patients taking fewer non-HIV medications.
“We found an association between polypharmacy and noncontinuous ART,” write the investigators. “The next therapeutic challenge in HIV care is polypharmacy due to the aging of HIV infected populations and the inevitable increase in age-associated co-morbidities that may directly or indirectly impact on their HIV infection.”
Improvements in HIV treatment and care mean that most patients with HIV now have a good chance of living well into old age. Illnesses associated with ageing are now responsible for a large proportion of the serious disease now seen in patients with HIV. This means that many patients are taking a large number of medications for the treatment of non-HIV-related conditions.
Polypharmacy not only increases the number of pills a patient needs to take each day, but has also been associated with an increase in the risk of drug-drug interactions, side-effects and treatment non-adherence.
Given the risks associated with taking a large number of medications, investigators in Calgary hypothesised that ART-treated patients with polypharmacy would be more likely to stop or change their HIV therapy. To test this theory, they conducted an observational, single-centre study involving 1190 patients who were treated with ART between 2011 and 2013. Data on polypharmacy were collected at baseline and at six-monthly intervals during follow-up.
Approximately a third of patients stopped or changed their ART. Compared to individuals on continuous therapy, patients stopping/changing treatment were more likely to be female, under 30 years of age, have injecting drug use as their HIV risk factor and have a CD4 count below 200 cells/mm3 (all p < 0.05).
Most patients (95%) were taking a three-drug ART regimen with 4% taking a combination of four agents. One-daily ART was used by 64% of patients, the remaining 36% taking twice-daily therapy. Over 88% of individuals were taking ART with a daily pill burden of two or more pills.
Nearly a third (32%) of patients had non-ART polypharmacy. This was associated with increasing age (p < 0.01), injecting drug use (p < 0.05), lower CD4 count, an AIDS diagnosis and longer duration of HIV infection (all p < 0.01).
Patients taking a greater number of pills as part of their ART, and also those treated with regimens that required twice-daily dosing, were more likely to experience non-HIV-related polypharmacy when compared to patients treated with less complicated antiretroviral regimens.
Approximately a third (32%) of patients stopped or changed their ART. Patients with non-HIV-related polypharmacy were significantly more likely to have non-continuous ART compared to patients without polypharmacy (37% vs. 30%, respectively, p < 0.01). The relationship between polypharmacy and non-continuous ART was especially strong for patients taking twice-daily antiretroviral regimens (39% vs. 28% for non-polypharmacy patients, p < 0.01).
Factors associated with stopping or changing ART included non-adherence (51%), side effects (31%), drug interactions (6%) and ART failure (6%). Patients experiencing polypharmacy had a non-significant increase in the risk of non-continuous ART due to side effects.
“As people with HIV infection live longer, they will likely and increasingly encounter a co-morbid condition requiring multiple medications. The interplay between ARV and non-ARV drugs has become increasingly complex and challenging for both patient and physician,” conclude the investigators. “Physicians, pharmacists, and patients should work together to anticipate and control for the contingencies associated with polypharmacy.”
Krentz H et al. The impact of non-antiretroviral polypharmacy on the continuity of antiretroviral therapy (ART) among HIV patients. AIDS Patient Care and STDs, 30, DOI: 10.1089/apc.2015.0199 (2015).