Many Parents With Poor Math Skills Give Kids Wrong Doses

Daniel M. Keller, PhD

May 04, 2012

May 4, 2012 (Boston, Massachusetts) — Limited quantitative skills in many parents lead to dosing errors in the medications that they give to their children.

In a study by researchers from the Department of Pediatrics at New York University School of Medicine and Bellevue Hospital in New York City, 40% of parents made errors, primarily underdosing. More than two thirds of parents had poor quantitative skills, or "low numeracy," third-year resident Christine Marrese, MD, reported here at the Pediatric Academic Societies 2012 Annual Meeting.

She said the literature shows that at least half of parents give incorrect doses of medications, accounting for 70% of preventable pediatric outpatient drug adverse events. Contributing to the problem is the difficulty of administering liquid medications because of different concentrations, different units of measure, and the wide variety of dosing instruments (e.g., droppers, syringes, and graduated cylinders or cups).

Previous studies have investigated the link between health literacy and rates of dosing errors and nonadherence. However, this study is the first to examine the contribution of parental numeracy — the ability to count, quantify, and compute amounts and proportions in everyday health situations — to liquid medication dosing errors, according to Dr. Marrese and colleagues.

The study was a cross-sectional analysis of baseline data from a study of an intervention to enhance medication counseling conducted in 2 urban pediatric emergency departments. It involved children younger than 9 years who were prescribed liquid medication for up to 2 weeks, where an English- or Spanish-speaking parent was responsible for administering the medication.

Specific validated tests of functional health literacy were used to evaluate prose reading comprehension, numeracy, and arithmetic ability. Observed dosing accuracy was assessed in person 2 weeks after enrolment, and the measured dose was considered accurate if it was within 20% of the prescribed dose. Four hundred parents were enrolled and 284 underwent an in-person assessment.

Mean parental age was 32.3 years; 74% of the cohort was Hispanic, 61% was born outside the United States, 83% was of low socioeconomic status, and 49% had not graduated from high school. The researchers classified 28% of the parents as having inadequate or marginal health literacy, 84% as having inadequate or marginal numeracy, and 71% as having arithmetic skills below the sixth grade level.

Low Numeracy Leads to High Medication Errors

When tested, 41% of parents made a dosing error outside the allowable margin for error (34% underdosed and 7% overdosed). Low numeracy and arithmetic skills were the strongest predictors of dosing errors. After adjustment for parental demographic factors, child age, and medical problems, parents with inadequate numeracy were almost 4 times as likely to make medication errors as parents with adequate numeracy (adjusted odds ratio [AOR], 3.9; 95% confidence interval [CI], 1.3 to 12.0; P = .009).

Arithmetic skills below the fourth grade level were associated with an almost 5-fold propensity to make dosing errors (AOR, 4.7; 95% CI, 2.1 to 10.4; P < .001). The researchers did not find a significant association between prose health literacy and dosing errors.

The researchers conclude that low numeracy is a prevalent problem in the population studied and that it is significantly associated with medication dosing errors. However, they note that the study is cross-sectional, which limits the ability to infer causality. Furthermore, the results might not be generalizable beyond this specific population of primarily Hispanic families of low socioeconomic status. The researchers suggest that strategies to address parents' numeracy skills will help decrease medication dosing errors for children.

Session moderator Fernando Mendoza, MD, MPH, professor and chief of the division of general pediatrics at Stanford University School of Medicine and Lucile Packard Children's Hospital in Palo Alto, California, who was not involved in the study, said it is well known that underdosing might not adequately treat the illness and overdosing can lead to adverse effects that can either bring the child back to the physician or decrease compliance.

The problem is how to communicate instructions well and help parents understand how to dose medications. "People can learn. I think the question becomes how do we teach them. How do we make it more simple?" he told Medscape Medical News. "Dosing regimens are all over the place — in milliliters, ounces, ccs. It's incumbent upon the healthcare system and physicians to think about this as part of their management." Technology in the form of electronic devices or dosing aids could help.

Dr. Mendoza said healthcare providers need to consider parents' abilities to deal with medication dosing. "All this is about perspective.... If you write a prescription and you give it to the patient, the assumption that most physicians have is that they're going to take what you actually wrote, the pharmacy is going give it the right way, and the parents are going to [give it as prescribed]. Studies like this really emphasize how we have to rethink some of the doctor–patient interactions," he said. "As healthcare reform comes about, it's going to be about how well can we take care of patients, rather than how many times can we see them. That will be a big behavioral change for a lot of physicians."

Furthermore, communication styles and techniques will need to be individualized to different communities, kinds of practices, and kinds of patients. There is "a lot of diversity in our patients.... It's probably the most diverse that it's ever been in the history of the country, with languages and cultures. I think it's a challenge for us to meet that," Dr. Mendoza pointed out. "The demographic shift in the population, particularly in kids, is really affecting everything; it's no longer peripheral.... We really need to deal with the aspect of diversity, and literacy is clearly one of those aspects."

He noted that the problem is not restricted to ethnic communities or lower socioeconomic status. "This is also seen in middle-class white families... This kind of effort in health literacy is really important. At the end of the day, it's going to impact all of medicine," Dr. Mendoza predicted.

Dr. Mendoza has disclosed no relevant financial relationships.

Pediatric Academic Societies (PAS) 2012 Annual Meeting. Abstract 1315.7. Presented April 28, 2012.