“Placebo cough treatment benefits children and their parents, study suggests,” The Daily Telegraph reports.

A US study found that children’s reported cough symptoms improved even though they were just given a dummy treatment (placebo).

The study compared the effectiveness of agave nectar (a sweet syrup similar to honey, from the agave plant), placebo (flavoured coloured water) or no treatment for night-time cough in 119 children aged between two and 47 months old. Parents were given surveys to record cough symptoms over two days.

Agave nectar and placebo both provided more relief from cough symptoms than no treatment, but there was no difference in relief between agave nectar and placebo.

It is possible that as parents were assessing their children’s symptoms, this could be an example of the placebo effect. That is, parents who thought they were giving their child some syrup, rather than giving nothing, felt that it helped their child’s symptoms. The placebo effect, where people get better because they expect to get better, may sound unlikely, but it has been well documented for decades.

It is also possible that giving something to swallow – either syrup or plain water – is better than nothing when trying to ease a child’s cough.

The best thing that you can do to help a young child with a cough or cold is to make sure that they stay well hydrated with plenty of warm drinks. Honey shouldn't be given to babies under the age of one, due to the risk of infant botulism.

Where did the story come from?

The study was carried out by researchers from Penn State College of Medicine, Pennsylvania, and was funded by an unrestricted grant to the Penn State College of Medicine by Zarbee’s Inc, which makes a number of products, including cough syrups. One of the study’s authors has worked as a paid consultant for Zarbee’s Inc, which represents a potential conflict of interest. However, seeing as the main result of the study was that placebos were as effective as agave syrup in treating coughs, it would appear that the study was free of any commercial interference or influence.

The study was published in the peer-reviewed medical journal JAMA Pediatrics. This article was open access, so can be read for free online.

The research was well covered by The Daily Telegraph, though it should be noted that the research article is published in JAMA Pediatrics rather than JAMA Neurology, as the paper wrongly stated.

While the focus of the news - and indeed the title of the research paper - suggest that scientists were looking at whether placebos work for cough mixture, by definition placebos don’t work (except via the placebo effect). In fact, the researchers were testing whether a new formulation of agave syrup could improve cough symptoms. It didn’t improve symptoms any more than placebo.

What kind of research was this?

This was a randomised controlled trial (RCT) that aimed to compare the effectiveness of novel pasteurised agave nectar, compared to placebo or no treatment, on nocturnal cough and sleep difficulty associated with acute cough in infants and toddlers.

Agave nectar is a syrup similar to honey that is produced in Central and South America. Unlike honey, it hasn’t been associated with botulism.

An RCT is the ideal way to compare the effectiveness of different treatments.

What did the research involve?

The researchers studied 119 children aged between two and 47 months old, who had a cough for seven days or less and visited their GP. Children had a non-specific cough, meaning it was not thought to be due to any particular disease or condition and most likely due to a viral infection. These types of infections are common in young children, as their immune systems are underdeveloped.

They could have other symptoms of a temperature, runny nose or congestion, but were excluded from the study if they had symptoms suggesting more serious conditions, such as asthma or pneumonia.

Children were also ineligible if they had used any medication or honey to treat their cough within six hours of bedtime on the evening before or on the day of enrolment.

Parents were asked to complete a questionnaire about their child’s symptoms the night before. They were asked to rate between one (not at all) to seven (very often/severe):

how often did your child cough last night?

how severe was your child’s cough last night?

how bothersome was your child’s cough last night?

how severe was your child’s stuffy nose last night?

how severe was your child’s runny nose last night?

how much did last night’s cough affect your child’s ability to sleep?

how much did your child’s cough affect your own ability to sleep last night?

The parents of the studied children reported at least “moderately often” or “moderately severe” (a score of four or more) on at least two of three questions related to cough frequency, cough effect on child sleep and cough effect on parent sleep.

The children were randomised to:

grape-flavoured pasteurised agave nectar (from Zarbee’s Inc, which funded the study)

coloured grape-flavoured water (placebo)

no treatment

The children received one of these options 30 minutes before bedtime.

Within 30 minutes of waking, the parents again completed the same questionnaire about their child’s symptoms.

The researchers compared the change in symptoms between nights for the three different groups.

What were the basic results?

Within each study group, symptoms significantly improved from baseline.

When treatment-night effects of agave nectar, placebo and no treatment were compared, agave syrup and placebo were both superior to no treatment for all symptoms apart from how bothersome the cough was.

However, there were no significant differences in any outcome when agave syrup was compared to placebo.

How did the researchers interpret the results?

The researchers concluded that “in a comparison of agave nectar, placebo and no treatment, a placebo effect was demonstrated, with no additional benefit offered by agave nectar. Health care professionals should consider the potential benefits and costs when recommending a treatment with only a placebo effect for infants and toddlers with non-specific acute cough.”

Conclusion

This RCT compared the efficacy of agave nectar, placebo or no treatment for night-time cough in children aged between two and 47 months old.

Agave nectar and placebo both provided more relief from cough symptoms than no treatment, but there was no difference in relief between agave nectar and placebo.

It's possible that as parents were assessing their children’s symptoms, this study could be an example of the placebo effect. That is, parents who thought that they were giving their child some syrup, rather than giving nothing, felt that it helped their child’s symptoms. Equally, it is possible that giving something to swallow – either syrup or plain water – is better than nothing at helping to ease a child’s cough.

All children included in this study had a cough for less than a week and other cold-like symptoms, such as runny nose or congestion. This is likely due to a viral infection and requires no specific treatment. There is no good evidence that over-the-counter cough medicines actually work against an acute cough. The Medicines Regulatory Agency in the UK currently advises that over-the-counter cough and cold medicines shouldn’t be given to children under six years. Honey also shouldn’t be given to children aged under one.

The best thing you can do to help a young child with a cough or cold is to make sure that they stay well hydrated with plenty of warm drinks.

The study does highlight the remarkable impact the placebo effect can have in certain cases. There are libraries full of evidence showing how symptoms can dramatically improve for a range of conditions, even though a patient was given a sugar pill or a salt water injection. This may suggest that the mind can have a considerable effect on the symptoms of the body in some cases.

Analysis by Bazian

Edited by NHS Website