Dosing errors are
“exceedingly” common when adults are preparing paediatric doses of liquid
antiretrovirals, results of research published in the online journal of AIDS show. The cross-sectional study
involved 316 HIV-positive adult patients, all taking combination HIV therapy.
They were asked to prepare 2.5ml doses of liquid AZT (zidovudine, Retrovir) using both a
cup and a syringe with appropriate dose markings. Approximately 50% of doses
were incorrectly prepared. Higher HIV-related health literacy was associated
with a reduced risk of dosing errors.
were exceedingly common and were associated significantly with lower HIV health
literacy,” write the authors. “Our study highlights serious concern as to an
adult’s ability to accurately dose infants for PTMCT [prevention of
mother-to-child transmission] or child cART [combination antiretroviral
therapy], even adults who are receiving cART for their own care.”
antiretroviral formulations are used for both the prevention of HIV infections
in infants and also for paediatric HIV therapy. However, little is known about
the ability of caregivers in low- and middle-income settings to accurately
administer liquid antiretroviral doses to children. An international team of
investigators therefore designed a study to determine the frequency of such
errors. They hypothesised that lower health literacy would be related with an
increased risk of errors.
The study was
conducted in Maputo Province, Mozambique. The population comprised a
convenience sample of HIV-positive adults aged between 18 and 49 years. All had
been taking combination antiretroviral treatment for at least three months.
asked to measure a theoretical 2.5ml dose of liquid AZT using both a cup and
syringe. The cup had etched marks at intervals of 2.5ml. The syringe had marks
at each millilitre interval. A dosing error was a dose that was 20% above or below the
2.5ml dose; a major dosing error was incorrect by a margin of 40% or greater.
literacy was assessed using a test of literacy and numeracy applied to an HIV
care context. The test was marked on a scale of 0 to 16 with higher scores
indicating greater literacy.
Data were gathered regarding the participants’ age and education. They were also asked if
there were children in their household, and if any were under the age of five
years – the age group most likely to require liquid antiretroviral
The mean age was
35 years and 90% of participants had one or more child in their household, with
approximately half having at least one child under the age of five in their home.
Overall HIV health
literacy was poor, the median score just 6.7. Scores were strongly correlated
with general numeracy and literacy and level of education.
With both the cup
and the syringe, 50% of participants made a dosing error, including 28% making a major
dosing error. Approximately 90% of errors using the cup involved
over-dosing, whereas 58% of errors with the syringe were under-dosing errors.
Higher HIV health
literacy scores were associated with reduced odds of any dosing error with a
cup (p = 0.03) or syringe (p < 0.001)
and also a major dosing error using both these implements (p = 0.001, p = 0.01,
The results were
similar when the investigators focused on people caring for children aged less
than five years.
suggest targeted interventions to improve instructions about paediatric liquid
ARV dosing are needed to improve paediatric ARV adherence, particularly in
settings dependent on liquid formulations,” state the researchers. They suggest
the assessment of HIV-related health literacy “could be used in clinic settings
to identify caregivers of HIV-exposed/infected children who may benefit from
additional dosing instructions or counselling strategies”.