Impact of preschool wheeze and novel risk factor for asthma

Published: January 12, 2021

Wheeze is one of the most common symptoms of preschool children, contributing to a large healthcare cost and causing significant family stress. Previous studies have used surveys of families following children from birth to childhood to understand how common wheeze is and if these preschool children, under 5 years of age, go on to develop childhood asthma. The findings from such surveys have shown a lot of variation in findings, in part because they rely on parents answering the surveys and are expensive so cannot include huge numbers of children. An alternative source of data is to use medical records.

Bloom and colleagues at Imperial College London analysed a large UK database of over 1 million community medical records from preschool children. Their study, published in The Journal of Allergy and Clinical Immunology (JACI), measured how common wheeze is, what treatments children are given and how often they have to go to Emergency department or are admitted to hospital with wheeze. Bloom et al also investigated which factors increase the risk of these children developing asthma between the ages of 5 and 8 years old.

Around 8% of UK preschool children were found to have visited their doctor due to wheeze. Approximately one-third were prescribed steroids, usually inhaled steroids but one in seven were given oral steroids. Hospital attendance for wheeze was also common, over a two-year period, 16% attended the Emergence Department and 14% were admitted to hospital. The study confirmed many risk factors for developing childhood asthma including, being born premature, frequently suffering with wheeze, having a history of allergies and having a mother with bad asthma during pregnancy. A novel significant risk factor was having their first wheeze, that was reported to a doctor, in the month of September. Other speculated factors were not found to be a risk, e.g., being born by Caesarean section or having a mother with a history of allergies.

This is the largest study of wheeze in preschool children. Around 1 in 12 children experienced wheeze that was significant enough to be reported. These children consume a large amount of healthcare resources, including high number of prescriptions and unplanned hospital visits. Many children were managed with steroids, more than is recommended in clinical guidelines. Around half of the children that reported wheeze to their doctor went on to develop childhood asthma. There are several risk factors, a previously underappreciated risk is having wheeze in September. In the UK, the spread of rhinovirus has a peak in September and has previously been shown in laboratory studies to be associated with the risk of developing asthma. This is also in keeping with the seasonal pattern of wheeze that occurs in children, thought to be influenced by exposure to viruses.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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