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Spoon measurements contribute to many child drug-dosing errors

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​NIH funded researchers recommend shift to milliliters only

Friday, August 29, 2014

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Barrett Whitener: Using a teaspoon or a tablespoon to give children medicine doubled parents' chances of giving an incorrect dose, according to researchers funded by the National Institutes of Health. Instead of spoons, the study authors recommend that all liquid medicines be given to children in milliliters. A big part of the problem is parents confusing medicine spoons with kitchen spoons. Many people confuse the two. Errors, the researchers found, are much less likely when parents use medicine droppers and oral syringes calibrated in milliliters.

Children are more sensitive to many drugs than adults, so even a small dosing error can have serious consequences. Every year, poison control centers receive more than 10,000 calls because the wrong dose of liquid medications was given to a child.

The study found that nearly 40 percent of parents incorrectly measured the dose they intended to give and over 41 percent made an error in measuring what their doctor had prescribed.

From the National Institutes of Health, I'm Barrett Whitener. This is Research Developments, a podcast from the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development, the NICHD.

With me today is the study's lead author, Shonna Yin, of the Department of Pediatrics at the New York University School of Medicine and Bellevue Hospital Center. Her study was funded in part by the NICHD. Thank you for joining us today, Dr. Yin.

Dr. Shonna Yin: It's great to be here today.

Mr. Whitener: Dr. Yin, others have suggested replacing spoon measurements with milliliters. Why did you conduct this study?

Dr. Yin: Well, in the United States, there has been growing concern about the high rate of parent medication dosing errors. For young children, liquid formulations of medications are typically used, and dosing liquid medications for children can be especially confusing for parents for a number of reasons.

One reason is that for a single prescribed medication, different units of measurement like milliliters, teaspoons, and tablespoons may be used interchangeably as part of dosing instructions when parents are being counseled by their doctor or pharmacist, and when the dose is shown on the prescription or medication bottle label.

And when parents confuse teaspoons with tablespoons, this can lead to a three times over- or under-dose, and when parents confuse milliliters with teaspoons, this can lead to a five times over- or under-dose.

Having more than one unit of measurement can also be confusing for providers as well. For example, there have been cases in which pharmacists have confused units of measurement, leading to cases in which parents have overdosed their children.

The second reason is that terms like teaspoons and tablespoons also inadvertently endorse the use of kitchen spoons, and kitchen spoons, as we know, vary greatly in size and shape, making it difficult for parents to measure their child's dose of medication accurately. And that's why it's generally recommended that parents use standard dosing tools like oral syringes, droppers, or dosing spoons, that have markings on them to help guide parents to dose the right amount.

So, because of concerns related to these issues, groups like the Centers for Disease Control and Prevention, the American Academy of Pediatrics, and other groups have suggested a new strategy to reduce medication errors, moving to use the milliliter as the single, standard unit of measurement for pediatric liquid medications.

The problem is that one fear that people have is that moving to a milliliter standard would actually potentially cause more confusion. They think that parents are familiar with terms like teaspoons and tablespoons. So we conducted this study to get a better sense of how parent understanding of terms like milliliters and teaspoons relate to how well parents dose medications for their children.

Mr. Whitener: How did you conduct the study?

Dr. Yin: So, we looked at data that we were collecting as part of a larger study of medication errors and doctor-parent communication that was being done in two public hospitals in New York City. The study included 287 English and Spanish-speaking parents of children who were prescribed liquid medications by their doctor in one of two emergency departments. These parents were interviewed by phone at the end of their medication course and asked questions about the amount of medication their doctor prescribed to their child. And the dose, including the unit of measurement they used, was written down exactly as they said it, and then parents returned to the hospital to show us how they dosed their child's medication.

We looked at the child's hospital record to see what was actually prescribed and compared it to what the parents said their child's dose was, as well as the amount they measured for us.

Mr. Whitener: You looked at two types of measurement errors. Why was that?

Dr. Yin: So, we looked at what the parent intended to dose, so we asked what the parent reported their child's dose was, and then we saw whether or not they were able to measure what they intended to dose. And then we also looked at what the parent measured and compared it to what was actually prescribed. So, that's a little more what was like clinically, a clinically significant error.

Mr. Whitener: Could you tell us a little bit more about what you found?

Dr. Yin: So, similar to what other studies have found, we found that many parents are making errors in dosing liquid medications for their child, so in our study more than 40 percent of parents made errors. But what was really interesting was, we found that dosing using spoonfuls can be very confusing for parents when they're measuring liquid medications for their children. So parents who thought of their child's dose in teaspoons and tablespoons had twice the odds of making a dosing error, compared to parents who dosed using milliliters only. And parents who thought of their child's dose in teaspoons and tablespoons were also much more likely to use kitchen spoons to dose, so 30 percent of those who thought of their child's dose in teaspoons and tablespoons used kitchen spoons rather than standard instruments like oral syringes, droppers, or cups, compared to just 1 percent of those who thought of their child's dose in milliliters.

Mr. Whitener: And for the parents listening, can you clarify exactly why a kitchen spoon is a bad idea to use?

Dr. Yin: Yes, because kitchen spoons, they're not standard, so they don't—they can measure a wide range of doses. And it's a lot easier to make an error when you're dosing using kitchen spoons, compared to when you're using a standard instrument like an oral syringe, or a drop, or a cup. There are actually markings on those that tell you exactly how much you're measuring.

Even among parents who used a standardized dosing instrument, parents who dosed using teaspoons rather than milliliters were still more likely to make dosing errors. We also saw that the link between teaspoon-tablespoon use and dosing errors was especially strong among those with low health literacy and non-English speakers. And our findings provide support for moving to a standard, single-unit system based on milliliters as a way to reduce parent confusion, as a way to make it easier for parents to give their children the right dose of medicine.

Our findings also support that those with low health literacy and non-English speakers might especially benefit from a move to a simpler, milliliter-only system.

Mr. Whitener: And just for definition purposes, by low health literacy you mean those who don't have access to or don't understand basic health information?

Dr. Yin: Exactly.

Mr. Whitener: What do you think would help reduce the problem of incorrect dosing for children?

Dr. Yin: One of the things that could really be helpful is if we can move to a simpler milliliter standard, and in order for the country to move to a milliliter standard, we would need to continue to build consensus around the importance of this issue. We would need to engage in a national conversation to discuss the implications of moving to a milliliter standard, and how to best go about moving to a milliliter standard. It would be important to reach out to prescribers, to pharmacists, other health care providers, health care systems, and pharmacies, as well as manufacturers of medications and dosing instruments

Mr. Whitener: Now, you note in the paper that some have raised concerns about how using a milliliter-only standard could potentially increase error rates.

Dr. Yin: Yes, and what's really reassuring about the study is that we—what we found was that parents who dosed using milliliters were actually less likely to make dosing errors, and that parents who thought of their child's dose in teaspoons or tablespoonfuls were much more likely to use kitchen spoons, and much more likely to make a dosing error. So, these findings really do support a move to a milliliter standard, a metric systems where terms like teaspoons and tablespoons are no longer used, as a way to reduce parent confusion and decrease medication errors.

Mr. Whitener: Do you have any other advice for parents and caregivers?

Dr. Yin: Parents and other caregivers of young children should not be afraid to ask questions of their health care provider, to ensure that they know what the right dose for their child is. Parents and caregivers can ask their doctor or pharmacist to use milliliters when giving instructions about their child's dose. And parents and caregivers should ask their doctor or pharmacist for a standardized dosing instrument to use if they don't have one at home. They should never use a kitchen spoon to dose medications. An oral syringe is considered the most accurate instrument to measure medications with.

Mr. Whitener: I've been speaking with Dr. Shonna Yin. She's the lead author of the study, "Unit of Measurement Used and Parent Medication Dosing Errors," published recently in the journal, Pediatrics. Dr. Yin, thanks so much for joining us.

Dr. Yin: You're very welcome.

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About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's website at http://www.nichd.nih.gov/.

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