Respiratory experts in Southampton have found childhood wheezing can help to identify those most at risk of developing adult lung problems.
Researchers at Southampton General Hospital and the David Hide Centre on the Isle of Wight studied the effects of the breathing complaint in 1,456 patients who were recruited at birth in 1989.
They found that almost 60% of children who started wheezing during infancy and continued to the age of 10 - known as persistent wheezing - were still affected at 18 and had significantly impaired lung function.
The condition, which is recognised by a high-pitched whistling sound that occurs with a narrowing of the airways, is common among children from around the age of three but most outgrow it before adolescence.
Dr Claire Hodgekiss, a clinical fellow in asthma and allergy based at the David Hide Centre, said: "Until recently, wheezing during infancy was not thought to be associated with any significant respiratory health risks in adulthood.
"However, using our large group of long-term research patients, we've discovered wheeze can transcend adolescence into young adulthood and cause airway disease at 18 years, which is a new finding."
Led by allergy specialists Professor Hasan Arshad and Dr Ramesh Kurukulaaratchy at the NIHR Southampton Respiratory Biomedical Research Unit, the team reviewed the patients - known as the Isle of Wight Birth Cohort - at the ages of one, two, four, 10 and 18 and took a wheeze recording at each visit.
Persistent wheezers had significantly worse lung function - force of their breath, capacity and airflow through the lungs, inflammation and narrowing in the airways - at 18 compared to those who had not wheezed in the first decade of life.
They also found that 62% of persistent wheezers suffered from more than one common allergic disease, such as eczema, hayfever or asthma, and that the prevalence of current smoking among the group (44.4%) was almost double that of non-wheezers (24%) at 18.
In addition, persistent wheezers had been exposed to much more passive smoke between the ages of one and 18 (81.7%) than those who had not wheezed by the age of 10 (63.9%).
Dr Kurukulaaratchy, a consultant in respiratory medicine and allergy at Southampton General, said: "This work is really a red flag to recognise and properly manage persistent wheeze as early as possible during childhood in the hope that will lessen the negative impact we are seeing on adult lung health in this group.
"It should act as a prompt to ensure proper medical treatment of persistent early life wheezing and also to encourage people not to expose their children to cigarette smoke since that seems to be relevant to poor ongoing health."
He added: "Without action, these patients will continue into adult life with lower lung function which will contribute to problems such as bronchitis and infections."
Dr Hodgekiss said the research, which was presented at a meeting of the British Thoracic Society, raised "concerning associations" with tobacco exposure which require further attention.
"With smoking - both passive exposure and active - so prevalent among the persistent wheeze patients, we need to explore ways of reducing environmental exposure and educating those affected of the importance of avoiding smoking for their lung health," she explained.
Dr Hodgekiss and the research team are currently conducting a 26-year follow-up of patients in the Isle of Wight Birth Cohort to assess the impact of persistent wheezing later on in adulthood.
Anyone born on the Isle of Wight from January 1989 to February 1990 who would like to participate in the latest study can call the centre on 01983 534 898, text 07710 229 794, email IOWStudy@iow.nhs.uk or visit www.facebook.com/allergyresearchcentre for more information.