Respiratory infections contracted during early childhood are associated with an increased risk in death from respiratory illness between the ages of 26 and 73 years, according to a new study published in The Lancet. This first-of-its-kind study, which spans eight decades, suggests that although the overall number of premature deaths from respiratory disease was small, people who had a Lower Respiratory Tract Infections (LRTI), such as bronchitis or pneumonia, by the age of two were 93% more likely to die prematurely from respiratory disease as adults, regardless of socioeconomic background or smoking status. This could potentially account for one in five premature deaths from respiratory disease in England and Wales between 1972 and 2019 (179,188 out of 878,951 deaths). Chronic respiratory diseases pose a major public health problem, with an estimated 3.9 million deaths in 2017, accounting for 7% of all deaths worldwide. Chronic obstructive pulmonary disease (COPD) caused most of these deaths. Infant LRTIs have been shown to be linked to the development of adult lung function impairments, asthma, and chronic obstructive pulmonary disease, but it was previously unclear if there exists a link to premature death in adulthood. This new research is the first lifetime-spanning study on this topic, providing the best evidence yet to suggest that early respiratory health has an impact on mortality later in life. "Current preventative measures for adult respiratory disease mainly focus on adult lifestyle risk factors such as smoking. Linking one in five of adult respiratory deaths to common infections many decades earlier in childhood shows the need to target risk well before adulthood. To prevent the perpetuation of existing adult health inequalities we need to optimise 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," says James Allinson, Imperial College London, and lead author of the study. The study uses data from a nationwide British cohort (The National Survey of Health and Development), which recruited individuals at birth in 1946, and looks at health and death records up to the year 2019. Of the 3,589 study participants, 25% (913/3,589) had a LRTI before the age of two. By the end of 2019, 19% (674/3,589) of participants had died before the age of 73 years old. Among these 674 premature adult deaths, 8% (52/674) participants died from respiratory disease, mostly COPD. Analysis adjusting for socioeconomic background during childhood and smoking status, suggests children who had a LRTI by the age of two were 93% more likely to die prematurely as adults from respiratory disease, than children who had not had a LRTI by age two. This equates to a 2.1% rate of premature adult death from respiratory disease among those who had a LRTI in early childhood, compared to 1.1% among those who did not report a LRTI before the age of two. This risk accounts for one in five (20.4%) of premature respiratory-caused adult deaths, corresponding to 179,188 excess deaths from respiratory diseases across England and Wales between 1972 and 2019. In comparison adult respiratory deaths attributable to smoking account for three in five of deaths (57.7%) from respiratory disease in England and Wales over the same period (507,223 out of 878,951 deaths). Having a lower respiratory infection before the age of two was only associated with an increased risk of premature death from respiratory diseases, and not other illnesses, such as heart disease or cancers. "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," says Professor Rebecca Hardy, Loughborough University and University College London, UK. The authors acknowledge some limitations with the study. Although socioeconomic background and smoking were adjusted for in the analysis, there may have been other factors that were unreported, such as parental smoking and being born premature. During this life spanning study, societal change may also have driven changes in lung function of subsequent cohorts, altering outcomes. The study was not able to investigate which bacteria or viruses caused the LRTI in the children. Writing in a Linked Comment, Heather Zar, University of Cape Town, South Africa, who was not involved in this research, said: "Delineating the long-term effect of early life LRTI is important for understanding the origins of adult illness and for strengthening preventive interventions. Current global efforts to reduce premature adult mortality focus largely on adult exposures. The study by Allinson and colleagues 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."
