Children aged under 2 years who contracted a lower respiratory tract infection (LRTI) had almost a twofold higher risk of dying from respiratory disease as an adult than those who did not, according to a study.
It was previously only inferred that an LRTI in early childhood, when lungs were still developing, posed a significant risk factor for later respiratory disease, because no previous study had a long enough follow-up prospectively to connect those early childhood infections to adult mortality. However, UK researchers said they were able to establish an association using data gathered across eight decades. The discovery could potentially account for almost one in five premature deaths from respiratory disease in England and Wales between 1972 and 2019, they suggested.
The study, published in The Lancet, suggested that the findings challenged historically held assumptions that respiratory diseases, such as chronic obstructive pulmonary disease (COPD), resulted only from factors encountered during adulthood.
Cohort of Britons Born in the 1940s
The research, led by Imperial College London (ICL), used data from the National Survey of Health and Development, which recruited British individuals at birth in 1946 and followed up on their health and death records until 2019.
Of 3589 participants whose records were analysed, 913 (or 25%), who experienced an LRTI during early childhood were found at greater risk of dying from respiratory disease between the ages of 26 and 73 years than individuals who had no LRTI during early childhood (adjusted HR 1.93, 95% CI 1.10 to 3.37; P=0.021). The calculation was reached after adjustments for birthweight, sex, socioeconomic position during childhood, childhood home overcrowding, and adult smoking.
According to the researchers, if the association were causal, early childhood LRTI would account for 20.4% (95% CI 3.8 to 29.8) of premature adult deaths from respiratory disease between age 26 and 73 years, and an estimated 179,188 excess deaths across England and Wales between 1972 and 2019. In comparison, 57.7% of adult respiratory deaths were attributable to smoking over the same period.
Most of the deaths caused by respiratory disease within the investigation were due to COPD, and the researchers suggested "it is possible that our findings reflect childhood health influencing the development of this disease".
'Target Risk in Early Life'
Dr James Allinson from the National Heart and Lung Institute at ICL, who led the investigation, said: "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."
Professor Rebecca Hardy, from Loughborough University and University College London, and study co-author, said: "The results of our study suggest that efforts to reduce childhood respiratory infections could have an impact on tackling premature mortality from respiratory disease later in life. We hope that this study will help guide the strategies of international health organisations in tackling this issue."
Writing in a linked comment article in the same journal, Heather Zar from the University of Cape Town, South Africa, and Andrew Bush, professor of paediatrics at ICL, who were not involved in the research, said that the investigation "adds to the evidence that adults whose chronic lung disease has been attributed to smoking-related effects might also have disease resulting from childhood exposures that are largely preventable".
Funding for the study was provided by the National Institute for Health and Care Research Imperial Biomedical Research Centre, Royal Brompton and Harefield National Health Service (NHS) Foundation Trust, Royal Brompton and Harefield Hospitals Charity, and Imperial College Healthcare NHS Trust, UK Medical Research Council. Study authors' competing interests: NC participated in an advisory board for AstraZeneca. GCD received institution grants or contracts from Genentech and AstraZeneca; participated in advisory boards for AstraZeneca and Novatis; authored a book chapter for Elsevier. JAW received institution grants from AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline, Novartis, Genentech, and 37 Clinical; received consulting fees from AstraZeneca, Epiendo, GlaxoSmithKline, Gilead, Novartis, Pieris, and Pulmatrix; received speaker fees from AstraZeneca, GlaxoSmithKline, Boehringer Ingelheim, Recipharm, and Novartis; participated as data safety monitoring board chair for Virtus; was the editor-in Chief of the American Journal of Respiratory and Critical Care Medicine until March 2022. RH has received an institution grant from the Economic and Social Research Council. All other authors declared no competing interests.