SIDS, Outcome Research, and Proxy Measures

I mentioned a few days ago that Ed Clint of Skeptic Ink had objected to my comments on the research evidence behind the Back to Sleep/Safe to Sleep campaign to have parents put young babies in the supine position for sleep. Without concluding that a particular position was safest for infant sleep, I had queried whether the epidemiological research available actually provided evidence that supine sleeping reduces the rate of Sudden Infant Death Syndrome, as has been claimed. Now Ed has posted his own take on the situation, at http://www.skepticink.com/health/2014/12/11/back-sleepsafe-sleep-saveschildrens-lives/.

In his post, Ed included a familiar graph that shows 1.4 SIDS deaths for every 1000 live births in 1988, a gradual decline to 1.2 SIDS deaths per 1000 in 1992, the first year of the American Academy of Pediatrics recommendation for supine sleeping position, a reduction to 1.03 per 1000 in 1994, the first year of the Back to Sleep campaign, and then a continuing gradual reduction to a rate of 0.55 per 1000 in 2006. The graph also indicates changes in proportions of parents using prone or supine sleeping positions for their infants. From 13 % sleeping supine in 1992, this figure gradually rises to 75% in 2006.

This graph looks pretty significant, doesn’t it? Ignoring the fact that the rate of SIDS deaths was already decreasing before any recommendations for supine sleeping occurred, we see that the increase in the proportion of babies sleeping supine is accompanied by a decrease in SIDS deaths. It’s easy to assume that one caused the other… but of course the graph doesn’t show everything that could be affecting the SIDS rate. What other factors should we be looking at?

There are quite a few factors other than sleeping position that are associated with a lower or higher SIDS rate. Let’s just look at one of them—a variable about which much research has been done : tobacco smoking. Maternal smoking during and after pregnancy is known to be associated with a higher risk of SIDS. So, what has been happening about smoking during this period when the SIDS rate has been dropping? You can see this on slide 7 at www.cdc.gov/winnablebattles/tobacco/ppt/tobacco_wb_presentation_-oct2014_rev_508compliant.pptx. For those readers who hate trying to read graphs, I’ll describe what it shows: Between 1990 and 2010, a period roughly equivalent to the time shown on the SIDS and sleeping position graph, there was a reduction in cigarette smoking in the United States, from 3000 cigarettes per capita per year in 1990, to about 1000 in 2010. If we were to draw a new graph showing the relationship between SIDS and smoking, it would look very much like the association between supine sleeping and SIDS (only reversed, so that less smoking goes with less SIDS, whereas less SIDS goes with more supine sleeping, less prone sleeping).

Assuming for the sake of argument that SIDS is caused primarily by one of these two factors (which might not be the case), we apparently need to ask which one it is. The graphic representation of the relationships between SIDS and each of the factors look just alike. If we are going to have a campaign to reduce the SIDS rate, and we are going to tell people to do just one thing, which will it be--  don’t smoke, or don’t have the baby sleep prone? The figures don’t, and indeed can’t, answer this question, and can’t even tell us whether our two candidate factors are the only important ones. The choice is made for other reasons, and this is why I said that this kind of policy is in fact not strictly speaking science-based.

But let’s look a bit at the issue of whether either smoking or sleeping position is actually at work in affecting the SIDS rate. The problem with epidemiological research is that the factors looked at may be only proxy measures that are markers for the existence of some other factor that is more difficult to measure. Take, for example, a study that looked at (among other things) the effect of socioeconomic status on SIDS rates (Gelb, Aerts, & Nunes (2006). Sleep practices and sudden infant death syndrome: A new proposal for scoring risk factors. Sleep, 29, 1288-1294). Rather than do an elaborate and intrusive investigation into a family’s income and property to decide SES, these authors used maternal education as a proxy measure for SES, assuming that high maternal education is more likely among affluent families. Low maternal education was associated with the use of a set of high-risk sleeping practices, including not only prone position but soft bedding and allowing the child’s head to be covered during sleep. Young mothers and smoking mothers were more likely to use high-risk sleep practices, as were mothers who had fewer prenatal doctor visits. The mothers’ practices and their other characteristics were confounded in such a way that it was difficult to know what factor caused any outcome.

Proxy measures can be useful shortcuts to measurements that are hard to do. However, it’s important to remember that any factor chosen may in fact be a proxy measure that is determined by some background factor that is unnamed.  When parents choose to comply with advice about supine sleeping, is the factor that influences SIDS sleeping position itself, or is this just a proxy marker for parental characteristics such as carefulness, compliance with rules, middle-class status, education, and affluence? As developmental psychologists have proposed with respect to other topics, it may be that “good things go together” and that we don’t know which “good thing" is at work.

Choosing one “good thing” to work on may allow a simple campaign to be developed, but, once again, that choice is not based on clear scientific evidence about SIDS.

N.B. The point here is not to advise about infant sleeping positions, but to discuss the complexities of extracting helpful advice out of the available information.

Mistaken Attachment Beliefs, Persuasion, and "Trojan Horses"

I’ve been trying to figure out a name for a persuasive technique. Here’s an example: at www.imt.ie/clinical/2014/12/attachment-disorder-children.html, the authors Arshad and FitzGerald provide a good deal of well-substantiated information about children’s emotional attachment to their parents. They describe different qualities of attachment and refer to stages of attachment as they occur in the course of early development.

But now the trouble begins. Forgetting or ignoring the fact that insecure attachment is perhaps not ideal, but is within the normal range rather than pathological, these authors make the following statements: “Reactive attachment disorder is a severe form of insecure attachment, with symptoms of emotional dysregulation, anger, guilt, impulsive [sic], disinhibition, aggression, hostility, reactive [sic], proactive [sic], impulsiveness, stealing, hypervigilance, aggressive, withdrawn, destructive, temper outbursts, demanding, clinging, sleep problems, enuresis, overfamiliarity with strangers, oppositional, fidgety, poor hygiene, learned helplessness, abnormal eating habits, lack of eye contact, can’t keep friends, blames others for mistakes, mistrustful, manipulative, lack of remorse, irritable, fussy, swears, diffuse boundaries, and jealousy.” Rather than being supported by systematic research evidence, or drawn from any of the DSM discussions of Reactive Attachment Disorder, this symptom list is characteristic of websites like www.reactiveattachmentdisordertreatment.com.

The same technique is evident at www.attachmentnetwork.com and at www.radzebra.org. The latter has separate pages, one with material from DSM-IV and the other with a list of “symptoms” that are certainly concerning (like “fascination with blood and gore”--  by the way, is gore different from blood?) but that are not associated with disorders of attachment. These notional symptoms seem to have been drawn from the non-evidence-based 1996 article by Keith Reber which I discussed recently on this blog.

In the pages and documents I just mentioned, we have several examples of a persuasive technique. Trying to persuade people is not in itself a problem--  that’s something I am doing here, and even a simple presentation of well-founded statements is an effort at persuasion. However, persuasive devices are problematic when the goal is to convince readers that claims are correct, when they are not. It does not really matter whether the persuader is a true believer, has financial goals that depend on persuasion, or sees persuasion as a path to glory. Getting people to think that something is true when it is not is never really the right thing to do. In “wars of propaganda”, like World War II there may be short-term goals of persuasion that can lead to improved long-term outcomes, but even that use of persuasive devices may be based only on a guess as to what a good outcome may be. (Jane Austen’s novel Persuasion gives a good example of the difficulties here).

But what is the particular persuasive device seen in the examples above? It mingles true and false statements, apparently setting up an appeal to the authority of the true statements in order to “spread” that authority to cover the false statements as well. As I have tried to find a name for this device, I’ve found nothing among lists of fallacies or errors of critical thinking that might lead to persuasion in this way. There is such a thing as the fallacy of composition, which is the mistake of assuming that something true of a part of a whole must also be true of the whole, but that doesn’t seem to be exactly what’s going on here. I have found references to the method under the rubric of “disinformation” or intentional spreading of confusion about facts and logic, but no specific label to describe this technique as opposed to other disinformative methods.

Can any reader provide me with a name for a method that mixes true and false claims with the purpose of gaining belief for the false ones? In the absence of any other name known to me, I’m going to call this a “Trojan horse” technique. Presenting the reader with some well-established information, the “Trojan horse” user suggests the verity of ill-founded statements that have the potential to harm those who accept them. That’s certainly what appears to be happening in the examples given earlier, where accepting mistaken beliefs about attachment can lead to mistaken--  in fact, dangerous--  choices about treatment of children.

More About "Back to Sleep": The Neglected "Tummy Time" Part

Yesterday I posted some comments on the complex causes of Sudden Infant Death Syndrome (SIDS) (http://childmyths.blogspot.com/2013/12/sids-sleeping-position-and-single.html). I pointed out that there are many factors that increase the risk of SIDS--  that supine sleeping is not the only one, even though it has received the greatest emphasis by far. I ended that post by referring to adverse events associated with supine sleeping.

One of these unwanted side effects, deformational plagiocephaly, I have written about at http://childmyths.blogspot.com/2014/05/flattened-skulls-helmets-not-much-use.html. Lying in the same position for long periods can flatten an infant’s still-soft skull, which gradually hardens into an asymmetrical shape. Once flattening has begun, the baby’s head naturally turns to place the flattened area down, increasing the extent of flattening. But although the resulting asymmetry can have an effect on ear positions, it does not damage the brain or otherwise cause problems. (As anthropologists have pointed out, there have been many cultures that intentionally bound or flattened baby’s heads to get an appearance that they considered highly attractive.) Still, most parents today would rather their babies did not have flattened or asymmetrical heads, so paying attention to babies’ head positions and varying them is probably a good idea when babies sleep supine.

A more complicated side effect of supine sleeping as currently practiced by many parents is that some early events in motor development are delayed (see Pin, T., Eldridge, B., & Galea,M.P. (2007). “A review of the effects of sleep position, play position, and  equipment use on motor development in infants.” Developmental Medicine & Child Neurology, 11, 856-867.) The review by Pin et al indicated that motor delays are due not simply to supine sleeping in itself, but result from the lack of experience of the prone position during waking time. Here are the conclusions of this review paper: “In healthy infants born at term, those who spent time in prone when awake achieved developmental milestones significantly earlier than those who did not or who spent limited time in prone when awake in the first 6 months of life… Those infants who slept in supine attained developmental milestones significantly slower than the norm… before 6months of age…. most of these healthy infants born at term walked independently or developed within normal age limits. … Low-risk preterm infants who slept in supine attained head control… and rolling between supine and side and bringing hands to midline significantly slower than infants sleeping in prone or non-supine positions. All these preterm born infants walked independently within normal age limits”  (p.865).

Why would experiences with supine or prone positions make a difference to motor development? It’s easy to think that motor development just “automatically” progresses from the top to the bottom of the body, just as we see physical growth proceed in the cephalocaudal direction. But motor development involves both maturation of the nervous system and practice which leads to muscle development. Full-term newborn babies lie in a flexed “fetal” position and need both maturation and appropriate exercise to be able to extend the body. When babies are in the prone position, they can be seen working on this from the first days of life, lifting the head awkwardly and turning it from one side to the other. With arms under them, they soon become able to lift the head briefly to look around. Within a few months they can extend the arms enough to get the shoulders up, then chest up with fully-extended arms. These achievements depend on strengthening the muscles of the neck and shoulders by exercise. Babies who spend most of their time in the supine position will eventually develop muscles and motor skills, but the supine does not provide the same opportunities and challenges for mastery of arm extension as prone does, and it forces the baby to work against the pull of gravity.

Is this phenomenon of motor delays a problem? In one sense, no, it is not. The evidence is that these babies walk and show other motor abilities within a normal age range. This is not very surprising, given evidence about other cultures that limit babies’ movement capacities. Margaret Mead reported in the 1930s that Balinese babies were never permitted to crawl, this being considered “animal-like” and incongruent with the babies’ recent arrival from the divine realms. Yet, the babies walked independently within a normal age range. Similarly, Geoffrey Gorer described the use of swaddling for babies up to a year of age in Russia, but found that the babies walked independently within a normal age range even though they had had very limited experiences of independent movement.

In another sense, though, motor delays may be a problem. A common and effective way of assessing early development involves comparing an infant’s motor skills to norms developed by observing large numbers of babies. But the norms we have now were developed at a time when almost all babies slept prone, so they do not necessarily give a good comparison for babies who sleep supine. These “outmoded” norms make it difficult to know whether a young baby’s development is progressing in a typical way. This may be especially important now that there are reports of slow motor development as a predictor of later communication problems in infants at risk for autism (see Bhat, A.N., Galloway, J.C., & Landa,R.J. [2012]. “Relation between early motor delay and later communication delay in infants at risk for autism.” Infant Behavior & Development, 35, 838-846). The diagnosis of genuine motor delays may be important in more ways than one.

Is there anything that parents can do to encourage good motor development in their supine-sleeping  babies? The first step would be to use “tummy time” regularly and to work with reluctant babies to tolerate and later enjoy the prone position. “Tummy time” may be awkward at first, but the baby’s motivation for mastery of the environment will soon help move the process forward, especially if parents have been given good information about what to do.

  

Is there evidence that “tummy time” or other techniques do any good for motor development? There has been an experimental study showing the effects of a program to encourage motor development (Lobo,M.A., & Galloway, J.C. [2012]. “Enhanced handling and positioning in early infancy advances development throughout the first year.” Child Development, 83, 1290-1302). These authors noted that the prone position is challenging to young infants and that most caregivers tend to avoid it. They taught caregivers in the experimental group to do the following for 15 minutes each day, beginning when the infants were two months old: “placing them on the floor or [on the] caregiver while encouraging them to push up to lift their head.. pulling them up [by the arms] and lowering them down while assisting them to keep the head in line with their body…supporting them in sitting and standing while encouraging them to weight bear and to reorient their body upright with respect to gravity, and… moving their hands to midline for play to encourage a shift from lateral to more midline arm placement” (p. 1292). Caregivers in the control group put their babies in the supine position and played face-to-face with them for 15 minutes a day. The caregivers in both groups continued their activities for three weeks.

The  babies in the experimental group were earlier than the control babies in their achievement of reaching for an object at the midline, transferring objects from one hand to the other, creeping on hands and knees, walking with support, and walking independently. This intervention apparently counteracted the motor delays associated with supine sleeping.

I think an important point about the success of the handling and positioning intervention is that caregivers were carefully taught what to do with the babies. They were provided with an illustrated manual and a diary to record their activities with the babies. In addition, activities were suggested other than simple prone positioning--  the prone position being especially feared by parents who know that SIDS risk is much higher when babies who are accustomed to supine sleep are placed in prone. The usual casual admonition to ”do tummy time” does not convey much information to caregivers, and new parents who delay prone positioning until their baby is three or four months old will probably find that the baby objects strongly to an unaccustomed position, a situation that further discourages anything but supine positioning.

Perhaps an appropriate change in the “back-to-sleep” mantra would be “Back to Sleep; Tummy to Be Played With”.  Young babies don’t exactly play by themselves, but as the song says they can remind us how to play, and our mutual enjoyment can encourage good motor development.

     

SIDS, Sleeping Position, and Single-factor Theories

I had a disagreement last week with www.skepticink.com. I had submitted, and a moderator had  posted, a piece discussing whether the research evidence actually supports the idea that the use of supine sleeping positions for young babies is the cause of a reduction in Sudden Infant Death Syndrome (SIDS) over the last 20 years. People at skepticink apparently thought it was dangerous to babies even to talk about this possibility, took down my post, and have been unwilling to discuss the issue with me. As for me, my opinion is that it is dangerous to refuse to discuss controversial questions. If I had proposed that parents switch babies used to supine sleep over to a prone sleep position, that would have been dangerous, as it increases the risk of SIDS dramatically (see “The changing concept of sudden infant death syndrome: Diagnostic coding shifts, controversies regarding the sleeping environment, and new variables to consider in reducing risk” (2005), Pediatrics, 116, 1245-1255), but I did not do that, nor give any other recommendations about sleeping conditions.

My attention was  called back to this issue by an article in the New York Times (Saint Louis, C.,
“Federal study finds 55 percent of infants sleep with soft bedding, raising risk of death “, Dec. 1, 2014, p. A21 , reporting on a recent article in Pediatrics. The study used data from the 1993-2010 National Infants Sleep Position Study, which interviewed about 19,000 parents by telephone and examined changes in sleep practices year by year. The study reported that the use of soft bedding, blankets, and pillows, decreased by 23% between 1993 and 2000, but has not decreased much further, with 55% of infants in the United States still experiencing this known SIDS risk factor.

Could the problem here be that most of us, unless we try quite hard, tend to select one factor that we think causes an outcome, and to ignore all the other related factors? Few medical or developmental events have a single cause, so we are likely to be mistaken if we concentrate too hard on one factor. In addition, the great majority of developmental events are not only caused by more than one factor, they are also influenced by the ways those factors interact with each other--  the whole of the causes being rather more than the sum of their parts. Causes thus become too complex to lend themselves to easy solutions or slogans, but we tend to choose easy solutions anyway, even though that choice can make us neglect other important points.

From the earliest research on SIDS, it’s been clear that although prone sleeping position appears to play a role in sudden infant deaths, there is a list of further factors that have important effects. These are discussed in some detail in the 2005 Pediatrics article I mentioned earlier, so I will just list them: the use of soft bedding (an important point in the early New Zealand research on SIDS), exposure to tobacco smoke, failure to immunize, failure to breastfeed, failure to use pacifiers, overheating, premature birth and/or low birth weight.  Yet, as the recent study showed, the use of soft bedding continues; resistance to immunization is still present and even fostered by state laws supporting parental choice in medical care; smoking remains common in some populations, especially among the young mothers whose babies may have additional SIDS risk factors. As for the use of pacifiers, which would be an easy recommendation to make and carry out, there is still a sense of repugnance about them and a feeling that parents who give a pacifier have somehow failed.

Given this list of risk factors for SIDS, why is “Back to Sleep” the great recommendation to the public? The slogan sounds good (the baby will go back to sleep if she awakens in the night, it seems to imply) , and it provides a simple solution that appears to make it unnecessary to worry about stopping smoking or deciding to immunize. It’s hard to conceive a similar catchy slogan for avoiding soft bedding--  “Be Hard on Your Baby” doesn’t really work. Besides, once people have developed a single-factor belief about SIDS, another slogan will probably not catch on.

Please notice: I am not saying that I think babies should sleep in one or the other of the possible positions. I am saying that the claimed success for “Back to Sleep” (and there are reasons to question that success) may have occurred at the expense of forgetting about other SIDS risk factors.

I also want to comment on a nonfatal but problematic outcome of “Back to Sleep”. Parents who use the supine sleep position for their babies most often do not do the second part: “Tummy to Play”.  As a result, there have been considerable increases in the incidence of head shapes made asymmetrical by a baby’s constant lying position, and a tendency to delays in motor development milestones. I will be commenting on those issues in the next few days.

N.B. I now see that on Facebook Ed Clint of Healthy Skeptic has said that my statements about SIDS and sleeping position are comparable to someone without good evidence saying that all the statements of climate scientists are wrong. No, actually, what it's like is a student of the climate saying that more factors than human activity are responsible for global warming, and in order to understand the impact of human actions we must take into account what the other factors are and how they operate.   

5/20/15: For anyone who thinks I am way out of line to look at diagnostic categories as an issue here, you might have a look at https://eliminatechildabusefatalities_sites.usa.gov/files/2014/05/Transcript-Tampa-FINAL.pdf,  pp 11-12.