Contracting a lower respiratory tract infection in early childhood is associated with a higher risk of dying from respiratory disease as an adult, according to new research from Imperial College London.

The research, published in The Lancet, found that children who had a lower respiratory tract infection (LRTI), such as bronchitis or pneumonia, by the age of 2 were almost twice as likely to die prematurely in adulthood from respiratory diseases. The research showed the rate of premature death from respiratory disease was about 2% for those who had an LRTI in early childhood, compared to around 1% for those who did not. The findings remained after adjusting for socioeconomic factors and smoking status.

Previous research has linked infant LRTIs to the development of adult lung function impairments, asthma, and chronic obstructive pulmonary disease (COPD), but it has been unclear if there is also a link to premature death in adulthood. This study spans over 73 years and provides evidence that early respiratory health has an impact on mortality later in life.

The findings challenge the misconception that adult deaths from respiratory diseases are determined only by behavior in adulthood, such as smoking. The researchers say that this highlights the need to prevent childhood respiratory infection and improve the health of children through targeted public health measures and health service interventions, such as vaccination, improving living conditions, and better diagnosis and treatment of underlying health conditions.

The study was carried out in collaboration with researchers from University College London, Loughborough University, and Royal Brompton and Harefield NHS Foundation Trust.

“Current preventative measures for adult respiratory disease mainly focus on adult lifestyle risk factors such as smoking. Linking one in five adult respiratory deaths to common infections many decades earlier in childhood shows the need to target risk well before adulthood,” says lead author James Allinson, PhD, from the National Heart and Lung Institute at Imperial College London, in a press release. “To prevent the perpetuation of existing adult health inequalities we need to optimize childhood health, not least by tackling childhood poverty. Evidence suggesting the early life origins of adult chronic diseases also helps challenge the stigma that all deaths from diseases such as COPD are related to lifestyle factors.”

The study used data from a nationwide British cohort study called The National Survey of Health and Development, which recruited individuals at birth in 1946, to look at health and death records for 3,589 people up until 2019. Of the 3,589 study participants, 913 suffered a lower respiratory infection before the age of 2.

As the results show the childhood origins of health inequalities among adults who were born in the 1940s, improvements in childhood health and healthcare since this time may have led to better outcomes for children born today. However, evidence of the potentially lifelong consequences of poor childhood health highlights the need for renewed efforts to prevent LRTIs among children, according to researchers.

The researchers used a statistical model to estimate the association between a respiratory infection in early childhood and premature death from respiratory diseases in adulthood, whilst adjusting for different factors that can influence risk.

Analysis adjusting for socioeconomic background during childhood and smoking status suggested that children who had an LRTI by the age of 2 were 93% more likely to die prematurely from respiratory disease as adults, compared to children who had not had an LRTI by age 2. This equated to a 2.1% rate of premature adult death from respiratory disease among those who had an LRTI in early childhood, compared to 1.1% among those who did not report an LRTI before the age of 2.

The researchers say this increased risk potentially accounts for 179,188 premature deaths in England and Wales between 1972 and 2019, or one in five deaths from respiratory disease. In comparison, adult respiratory deaths linked to smoking account for three in five deaths from respiratory disease, or 507,223 excess deaths in England and Wales over the same period.

The researchers note that despite their adjustments, there may have been other risk factors that were unreported, such as parental smoking and being born prematurely. They also note that societal changes during the life-spanning study may have driven changes in lung function of subsequent cohorts and altered outcomes.