US and elsewhere use “bronchiolitis” to mean wheezing illness!  So beware definitions in studies.

Early aeroallergen sensitization predictive of ongoing symptoms and loss of lung function at school age, but does not predict response to treatment with inhaled corticosteroids (ICS)!

European Resp society task force diferentiate Episodic Viral Wheeze (EVW) from Multiple trigger wheeze (MTW) viz exercise, smoke, allergens.  Children may change categories over time.  Guides treatment.  But note that few RCTs have used this classification, and tend to conflate.

MTW is associated with more airflow obstruction, and the pathology (eosiniphilic inlfammation and remodelling) similar to asthma.  Eosiniophilic inflammation not seen in EVW.

Several clinical indices which attempt to predict future asthma – PPV generally under 50%.  Kids with EVW only have no increased risk of respiratory symptoms once they reach age 14.

No evidence that early ICS (intermittent or continuous) affects progression of disease.  [N Engl J Med 2006;354:1985-97 PMID 16687711]

Parental smoking linked to wheeze, asthma, bronchitis and nocturnal cough, with mean odds ratios all around 1.15, with independent effects of prenatal and postnatal exposures for most associations (PATY study (Pollution And The Young), n=53 879 children from 12 cross‐sectional studies).   “Not in front of the children” does not protect from effects [Jenny Pool, Cambridge – Thorax 2012;67:926]: 88% of children from families where parents only smoke outside still have detectable urine cotinine.  Nicotine levels in household dust and on surfaces is at least 3x higher in homes where parents smoke indoors, but still 5-7x higher in homes where parents smoke outside cf non-smoking houses [Tob Control 2004;13:29-37 doi:10.1136/tc.2003.003889].  Air pollution increases vulnerability to preschool wheeze, but no specific advice on individual exposure.

PREEMPT study of intermittent montelukast (1 week with onset of URTI) for EVW vs placebo reduced unscheduled consultations for asthma, days away from sc hool/nursery, parental time off work.  [Australia, Am J Respir Crit Care Med. 2007 Feb 15;175(4):323-9.] Similar findings from a US study, but not supported by much larger WAIT study, 3 way study of intermittent vs continuous montelukast vs placebo [Nwokoro, Lancet Respir Med. 2014 Oct;2(10):796-803. doi: 10.1016/S2213-2600(14)70186-9].  But “5/5 ALOX5 promoter genotype might identify a montelukast-responsive subgroup”? Discontinue when child is better, not after specified number of days!

Cochrane supports intermittent ICS for wheeze, but only due to small studies with unlicensed doses eg fluctic 750mcg BD!  No studies of combined ICS/montelukast.

No evidence for prophylactic continuous ICS, but studies looked at mild rather than severely affected children.   Could be tried if repeated hospital admission, in case interval symptoms underappreciated!  Beware growth suppression, review and wean/stop if able.

Hospital study of pred vs placebo (n=687) found no benefit!  SImilar study in primary care.  SO should not be automatic, esp when anticipated duration of admission less than 24 hours.

No evidence for treatment plans for preschool wheezers!

BMJ 2014;348:g15 Andrew Bush