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.”