Parsimony

Parsimony, ‘the quality of frugality in the use of resources’, is an unusual term. Unusual in that it has both pejorative (personal—meanness) and complimentary connotations. A parsimonious statistical model, for example, makes fewer assumptions, has fewer variables and has greater explanatory potential: in short, it is ‘better’.

My choices this month are all (in a positive sense) parsimonious. Each takes a question and, with a laudable lack of analytical ‘noise’, provides either an answer or new angle.

Aciclovir or Zoster Immune Globulin in the immunosuppressed child

Few areas generate the level of rigid adherence to tradition as post exposure prophylaxis (IV immunoglobulin or aciclovir) for immunosuppressed children in contact with varicella. To date, there have been no trials and the proponents of each method, likely, therefore to have been manacled by prior belief rather than evidence. It is hard to achieve consensus even over what constitutes ‘contact’: is it passing in the same school corridor, inadvertently playing with the sibling of child with active lesions or being a household contact?

In an admirable attempt to, if not fully resolve this question but to inform a subsequent trial, Bate and colleagues undertook a pilot across UK oncology centres screening for (eligible) seronegative children whom had had ‘contact’ with a case defined as greater than 15 min in the same room, at home or face to face conversation. Of those eligible, many declined for pragmatic reasons (travel, extra medication and blood tests) and the eventual numbers too small from which to draw any inferences. Were it not for the small but not negligible risks of IVIG, the matter could be allowed to rest. The risk, however, should compel us to continue rather than leave the issue languishing in the doldrums of equipoise, even though the answer will probably need a pan European and US collaboration to generate the numbers required for an adequately powered trial. See page 25

Smartphone cardiac monitoring

One of the frustrations of investigating palpitations in children, is knowing when to draw a line. Is a 48 hours/2 week recording reassuring: if so, why? Is there enough concern to consider a long term implantable event monitor? Add to this the discomfort children experience using the standard devices and the inevitable inconsistency in time leads are applied, and there is clearly scope a rethink. Macinnes and colleagues tested a one lead, easily activated, smart phone ECG in a group of children referred to their centre for assessment against a group of historical ‘controls’ whom had undertaken standard continuous monitoring. Though the groups cannot, of course not be directly compared, the rate of capture of arrhythmias was far higher in the phone group and the level of satisfaction greater. For better or worse, the majority of schoolchildren have a smartphone (and there are downsides to ubiquitous mobile phone ownership), this is one area where they can be put to unequivocally good use. See page 43

Obesity growth patterns

Few papers on obesity now say anything very new, but Isojima’s study on seasonal growth patterns in a huge cohort of Japanese preschool children is one of the rare ones that does. It is well known that the BMI in most children falls in winter and is lost again in the summer. In this cohort of over 15 000 children, an adverse growth pattern (greater rate of gain in the summer) was associated with and predictive of school entry obesity. The reasons are likely to be complex: sedentary behaviour and extra intake are possible, but, counterintuitive at this time of year. Is this perhaps the result of even earlier hypophyseal-hypothalamic programming? One would hope that identification at this early stage in life would be amenable to intervention, but, is that already too late? See page 53

Depression

Though the long term physical and metabolic consequences of obesity are only too well recognised, little attention to date has been paid to the psychological ones. Sutaria’s meta-analysis of observational studies (both cross-sectional and cohort) explores the association between obesity and depression. The 22 studies including 143, 000 children showed both contemporaneous and, more importantly, temporal associations between obesity and depression with an OR in the longitudinal studies of 1.5 (95% CI 1.21 to 1.88) noting persistent effects in girls These are not surprising, but, they are helpful and raise two questions: does one screen for depression at an earlier stage in the light of an adverse BMI trajectory and does this alter the threshold for treatment in an adolescent with obesity? How many of us really assess mood in children at the upper end of the BMI distribution: and, if not, why not? See page 64

Milk and mucous

In a brilliant thesis on the purported association between milk consumption and mucus, Ian Balfour-Lynn first takes us on a historical journey from the 13th century Egyptian court (the earliest record) to Saludin the Great’s treatise on asthma via Dr Spock’s seminal 1960s series Star Trek to the present day. The potential mechanisms are scrutinised, before the myth (and all its strands) is firmly debunked. A heady cocktail of history, anthro-sociology and science and my editor’s choice for the month. See page 91

This piece of folklore seems some way from where we started, but examined closely the parsimonious scientific approach becomes clearer. One hypothesis, one question and one answer: just like all good papers