PedSPAM June 1999

Welcome to PedSPAM for June. Here are some more things from my update reading that might interest you.

In the News

Our lead article this month of course has to be a discussion of the purported link of nearsightedness (myopia) and nightlight use reported in the May 13 issue of Nature by Dr. Richard A. Stone and colleagues, of the University of Pennsylvania School of Medicine.

Researchers began to investigate possible links between myopia and ambient lighting after noticing that perpetual lighting on poultry farms affects eye growth in chicks. The research team asked the parents of 479 children attending an ophthalmology clinic to complete a questionnaire detailing each child's light exposure from birth to 2 years of age.

They claim to have found a dose-dependent relationship of myopia to nighttime light levels. That is, the more light at night, the more nearsightedness observed. Sleeping in total darkness was reported to have a 10% incidence of nearsightedness; having a nightlight on raised this to 35%; and for children who slept with a lamp or the room lights on (75 out of 479), the incidence was 55%.

I must admit I was shocked by that one. I have to admit - I never asked. So I am going to do the first ever PedSPAM unscientific informational survey. If you leave a lamp or the room lights on all night for your children - email me; tell me how much light you use and for how long. I will report the number who do in the next PedSPAM.

The reporting of this study created quite a stir; I received a number of emails and questions in the office about it. I must say that I am thoroughly skeptical of this study and surprised it saw print in Nature.

Criticisms of the study are legion:

First, the obvious critcism of sample selection bias: these were kids with eye problems by definition - they were at the eye clinic already. This is not a representative sample of anything except kids with poor vision. Drawing any conclusions from it at all is perilous at best.
Next, the study is "retrospective." Parents were asked around age eight what had gone on years earlier. Such data is notoriously unreliable.
There was no quantification of ambient room light attempted beyond nightlight yes or no, or room lighting. There is no mention that a researcher even made any measurements of room light levels in actual households for comparison.
No proposed mechanism is advanced. Classic myopia is caused when the eyeball is out of round - it is too deep or long in relation to its height. How the diffence in photons striking the retina between
- eyes closed in a totally dark room
- eyes closed in a dimly lit room
might conceivable change the shape of the eye is "problematic."
Beware the fallacy of post hoc ergo propter hoc - "after this, therefore because of this." There may be an association, but that definitely does not establish cause and effect. Nearsightedness is known to be familial. Perhaps nearsighted parents are both more likely to use a nightlight or lamp to help themselves navigate in the night and also more likely to have nearsighted offsprings on a genetic basis.
Why do we only now notice this really striking effect? Has myopia spread across the globe like a plague in the last hundred years, a dreadful effect of the adoption of electric lighting?

Perhaps you recall the coffee causes pancreatic cancer scare of a few years ago. The researchers were so convinced of their findings that they all stopped drinking coffee. Of course, later they had to sheepishly admit that they had been gloriously wrong - mislead by their numbers, as so many are. Examples of this sort of scientific embarassment are legion. One comforting thought for scientists - the recantation is never given nearly as much publicity as the original (false) announcement.

At the end of the day, there may be something to this hypothesis; like a broken clock, bad science is right every once in a while. It just seems pretty far-fetched on its face. My personal prejudice has not been to place the very young in totally dark environments because of the problem of disorientation and fright when awakening from bad dreams. Until there is some sort of trustworthy prospective study done, I would counsel just do what you are doing already. Nature 1999;399:112-113

Surprise! State governors and legislatures are failing to use money obtained through the $246 billion settlement with tobacco firms for tobacco prevention programs aimed at reducing youth smoking, according to a report released by the Campaign for Tobacco-Free Kids and the American Heart Association. Rhode Island is considering a proposal to use the money to reduce its automobile tax, and Connecticut is debating whether to use the funds to reduce the state property tax. Only four states have made a commitment to fund tobacco prevention programs beyond a minimal level. Reuters Health

Mycoplasmas are germs that only live and multiply within infected host organism cells, a trait they share with viruses. However, they are treatable with antibiotics, since they are metabolically very similar to bacteria. Chronic infection with Mycoplasma pneumoniae may contribute to difficulties in clearing mild to moderate asthma. A University of Pittsburgh group has found that a subgroup of chronic asthma patients referred to their center because of failure to clear with standard treatments had low grade infection with the germ. Direct culture tests for the mycoplasma were negative in this group, but presence of the organism was proven by antibody studies. Treatment of the infection with standard antibiotics led to marked improvement in the patients' asthma symptoms. Reuters Health

Screening newborns for metabolic disorders is a strikingly successful strategy for reducing preventable mental retardation in children. Mass screening for metabolic and endocrine (glandular) disorders began in the 1970's. A researcher at the Centers for Disease Control and Prevention (CDC) in Atlanta reported that while statistically, in a 3 year time frame there would have been 148 affected children with retardation due to metabolic disorders, only two were found. The rest had early detection and treatment. Morbidity and Mortality Weekly Report 1999;48:353-356.

Amoxicillin and amoxicillin/clavulanate (Augmentin®) are superior to azithromycin (Zithromax®) in the treatment of acute otitis media. In a study reported at the Pediatric Academic Societies' annual meeting in San Francisco comparing the two drugs for new episodes of acute ear infection, the overall treatment success rate was 83% with amoxicillin/clavulanate and 49% with azithromycin.

Vaginal birth after cesarean is associated with a low risk of depressed Apgar scores and intrauterine fetal distress, according to Chicago researchers. The researchers estimate that the increased fetal risk associated with vaginal birth after cesarean compared to vaginal birth with no prior C-section may be on the order of one in one thousand. These figures are based "...on a one half to one percent risk of uterine rupture and a five to ten percent risk of fetal harm from oxygen deprivation in cases of uterine rupture," according to one of the researchers. Obstetrics and Gynecology May 1999;93:674-9

Pseudoephedrine (Sudafed®) is no better than placebo for reducing altitude-related ear pain in children who fly on commercial aircraft. Tis is true even in the subgroup of children who had experienced prior problems with flight-related ear pain. Interesting to me: 60% of children who took pseudoephedrine were drowsy compared with 27% given placebo. That's a switch. Archives of Pediatric and Adolescent Medicine 1999;153:466-468.

Dutch investigators claim that infection accounts for most pediatric headache in general practice. "More than half of the episodes were related to an infectious disease, among which upper respiratory tract infections predominated," they reported. Cephalalgia April 1999;19:147-150.

Preterm infants receiving dexamethasone (a steroid drug) for chronic lung disease have a very poor response to Hemophilus influenzae type B (HiB) immunization. These infants will require further immunization when steroids are stopped. Preterm infants who do not receive steroids have normal level of immune response to the vaccine, comparable to term babies. Archives of Disease in Childhood, Fetal and Neonatal Edition 80:F69-F71.

Dr. Theodore Rosen reported at the annual meeting of the American Academy of Dermatology that in African-American babies, a rash of closely set, itchy bumps arising from the hair follicles is a reliable precursor sign of impending atopic dermatitis (eczema). To avoid progression to atopic dermatitis, this rash should be very aggressively treated with applications of 2.5% hydrocortisone cream, avoidance of woolen blankets and rugs, avoidance of pet dander (dogs and especially cats), and the avoidance of excessive bathing and harsh soaps. Atopic dermatitis in African-American children can cause permanent patchy skin discolorations; Dr. Rosen recommends aggressive intervention to avoid this complication.

A long term survey study of high school seniors finds that rates of drinking and driving are on the rise among US teens. From a high of over 50% in 1984, the rate fell to less than 30% by 1995. In 1996 and 1997, however, the percentage was again above 30%. American Journal of Public Health 1999;89:678-684

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