Hydrogel dressings in the British Journal of Midwifery

August 15, 2009 — Elizabeth Jay

nurse-with-clipboardA few weeks ago, I talked about a ‘clinical case study’ posted on a medical supply manufacturer’s website, apparently demonstrating the benefits of using hydrogel dressings when breastfeeding. Unfortunately, the study was poorly designed, and therefore unable to provide support for its considerable claims. It showed, at best, that the dressings did not appear to cause any major problems for a small group of women.

Since then, the dressings have been tested in a larger, controlled study, published in the British Journal of Midwifery1. The article, which describes the dressings as ‘designed to physically protect wounds while maintaining a moist environment,’ concludes that, ‘the dressings can reduce the pain and discomfort associated with nipple excoriation.’ This rhetoric sounds pretty impressive – but does it accurately reflect the strength of the evidence?

On the surface, the study appears to be well designed and reported: 64 mothers were randomly assigned to either the experimental group (wearing dressings between feeds) or the control group (rubbing breast milk on the nipple after a feed), and self-reported pain scores were recorded in interviews 5 times over 14 days. If you read the article carefully, however, a number of inconsistencies become apparent. The abstract and ‘study objectives’ sections say that the aim of the study was to compare the dressings with ‘breastmilk expression and patient education (control group).’ We learn later that in fact both groups received education. The study hypothesis was that, ‘the dressings may reduce nipple pain and excoriation.’ While excoriation (skin wounding/abrasion) is mentioned several times, it was never actually measured – or if it was, the results are not reported.

That the dressings resulted in ‘a considerable reduction in pain’ is highlighted in a special ‘key points’ box. In fact, pain was significantly lower in the dressings group on only one occasion – day 12. The results section states that the average score for the dressings group on this day was 1.3, compared to 2.0 in the control group, and refers you to a graph showing how the scores declined over time. Confusingly, this graph shows the control group score on day 12 not as 2.0, but as 1.4. Clearly, one set of figures is wrong. Given the gradual downward trend of both sets of scores, it would be pretty odd if a pain score went from 1.4 two days previously, to 2.0 (the highest score, recorded at the start of the study), and back down to 1.4 two days later. It seems more plausible that the figures are misreported in the text, and that the statistical tests were in fact conducted with errroneous data. ‘Comfort scores’ are also reported to be consistently lower in the dressings group, although it is not completely clear what these are. They are not mentioned in the method section, and are described in the results section as ‘acceptance of the treatment’ measured using the 1-5 verbal descriptor pain scale. This is the same scale used to measure the other pain score, and how the two actually differ is not explained. Again, the graph and text do not match. The text says that comfort was recorded on days 3, 5, 10 and 12, but the graph also shows data for this measure on days 7 and 14. Interestingly, days 3, 5, 10 and 12 result in comfort scores of 1.0 for the dressings, whilst 7 and 14 show the scores as 1.2 and 1.4 respectively – is it possible these higher scores were conveniently excluded from the analysis?

There are other examples of sloppiness that call into question the integrity of the research. In the introduction, a paper is cited as saying that nipple pain typically starts to decline by day 12. In fact, the study reported in this paper only lasted 7 days2 (this same error occurs in the ‘clinical case study’ reported on the manufacturers website – one can only assume the authors copied the reference without actually bothering to check it). We are told 11 participants dropped out of the study, but not which group they belonged to (they could all potentially have been using the dressings). It is also not clear why 30 people were ‘randomized’ to the dressings group, and 34 to the control group. Why not have 32 in each? A presentation at the International Lactation Consultants’ Association (ILCA) Conference describing the study in progress stated there were 30 women in each group3; why the control group then increases by 4 (unbalancing the design) is a mystery. This presentation also said that breastfeeding duration was being analyzed. Why is this data not provided?

Given that these less than convincing results are reported with great enthusiasm, you would be forgiven for thinking that this might simply have been a promotional exercise. And that, of course, is precisely what it is. Although it is described as ‘sponsored’ research, and discretely labeled as a ‘product focus’, it is not a study that would ever have been published with a negative result.

If you ignore the problems with the figures, and simply take the data at face value, it is possible that the dressings may have provided increased ‘comfort’ for some women. The difference between the scores of the two groups is less than a point, however, and could conceivably be down to experimenter bias, as the investigators conducting the study may have been keen to obtain a positive outcome for their sponsor. Even if the effect is genuine, it certainly does not translate into the substantial support for the dressings claimed in the article. The dressings are marketed as having moist wound healing properties, and although these are alluded to frequently, they are never actually tested. Previous research has shown that hydrogel dressings do not help nipple wounds to heal more quickly when women are breastfeeding, and may potentially foster infection4. When you consider it in this context, what initially appears to be genuinely useful research, may in fact be harmful propaganda.

  1. Br J Midwifery. 2004 Apr;12(4):244-248.
  2. Nurs Res. 1995 Nov-Dec;44(6):347-51.
  3. J Hum Lact 2004; 20; 211.
  4. Arch Pediatr Adolesc Med. 1998 Nov;152(11):1077-82.
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Hydrogel dressings for breastfeeding: ‘a clinical case study’

July 23, 2009 — Elizabeth Jay

medicsIn the moist wound healing post, I discussed a number of peer-reviewed clinical studies that examine whether using dressings or creams to prevent nipples drying out helps them to heal more quickly (short answer: it doesn’t). While I was researching the post, I came across a ‘clinical case study’ on a hydrogel dressing manufacturer’s website, purporting to show the effectiveness of their product. As it is not really research, it wasn’t included in the moist wound healing post, but as it very much tries to appear as if it is, I thought it would useful to write about it anyway.

In the ‘study’, 10 women were supplied with hydrogel dressings within 24 hours of giving birth, and asked to wear them continually on both breasts when they weren’t feeding. Their effectiveness was measured, on the third and seventh days of wearing them, by asking the women to rate the levels of pain they experienced whilst they were breastfeeding, and in the time in between feeds. The scores, displayed in a rather unorthodox graph (where the between and during feed measures are inexplicably joined together with a line), appear to show that the dressings caused pain levels to gradually decline.

Of course, the fact that pain scores are lower on day 7 than day 3 does not necessarily mean the dressings are effective – the chances are, this would happen anyway. To demonstrate that the dressings cause the ratings to go down more quickly than usual, the paper Ziemer et al, 1990, is cited as evidence that without treatment it can take up to 12 days for nipple pain to improve. I have read this paper, and am a little surprised at the way the results have been interpreted: it actually reports that for the majority of women, nipple pain peaks on day 3, and declines thereafter1. If we assume that the ‘1990’ in the main body of text was in fact an error (there is no Ziemer et al, 1990, in the references at the end) and they actually meant to say Ziemer et al, 1995 (which is listed) the citation becomes even less appropriate. I have read this paper as well, and can tell you that the study that it reports ended at 7 days, and is therefore unable to say anything about nipple pain at 12 days2. There are numerous other studies not mentioned in the article that show that mean pain scores start to decline significantly within – who’d have thought? – 7 days of giving birth3.

The article concludes by saying:

The dressings’ moist wound healing properties were an aid in reducing pain and promoting nipple healing, without an increased risk of infection.

The observant among you will have spotted that neither wounds nor infections were monitored, so this claim is, of course, completely unfounded. It may also be wrong: research that has examined using hydrogel in a controlled setting reports that it may in fact delay wound healing and make mothers more vulnerable to infection4. Unsubstantiated or inaccurate statements about the effectiveness of a product are perhaps to be expected from a company trying to sell it. What is truly frustrating about this item of pseudo-science, however, is that it is endorsed by a midwife, lending it legitimacy. When women start breastfeeding they are often feeling stressed and vulnerable. If they can’t rely on health professionals to give them accurate, unbiased advice at this time, then it’s a pretty depressing state of affairs.

  1. West J Nurs Res. 1990 Dec;12(6):732-43; discussion 743-4.
  2. Nurs Res. 1995 Nov-Dec;44(6):347-51
  3. J Obstet Gynecol Neonatal Nurs. 2005 Jul-Aug;34(4):428-37.
  4. Arch Pediatr Adolesc Med. 1998 Nov;152(11):1077-82.
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