Researchers in Barcelona, Spain have conducted a study showing that low birth weight seems to be an independent risk factor for severe illness among non-elderly adults with coronavirus disease 2019 (COVID-19).
Fatima Crispi (University of Barcelona) and colleagues say the inclusion of low birth weight could improve the performance of risk stratification algorithms.
The analysis of almost 400 patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) found that low birth weight was associated with a 3.61 times greater likelihood of being admitted to an intensive care unit (ICU).
The findings were replicated in an independent cohort, including 1,822 individuals who self-reported SARS-CoV-2 infection via a web-based survey.
Crispi and the team say that if the findings are confirmed in future studies, low birth weight should be included in the assessment of non-elderly adults with SARS-CoV-2 infection to help identify who may require early intervention.
A pre-print version of the paper is available on the server medRxiv*, while the article undergoes peer review.
Transmission electron micrograph of SARS-CoV-2 virus particles, isolated from a patient. Image captured and color-enhanced at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID
Predisposing factors among healthy young adults remain unclear
While COVID-19 generally presents as a mild or asymptomatic disease in most patients, it still causes severe illness and even death in up to two percent of people.
To date, the main risk factors described for severe disease are older age, male sex, and co-existing health conditions. However, a small fraction of young and apparently healthy adults also eventually require critical care, and the factors that predispose these individuals to severe COVID-19 remain unclear.
“The identification of predisposing factors –particularly in a priori non-high-risk subjects- might allow early therapeutic measures eventually preventing serious evolution to serious illness,” say Crispi and team.
The link between low birth weight and poor adult health
The associations between low birth weight and adverse health effects in adulthood have long been recognized.
Defined as a weight of 2,500 grams or less, a low birth weight may be the result of fetal growth restriction or prematurity.
Fetal growth restriction has been linked to decreased lung function, cardiovascular morbidity, and respiratory disease in adulthood. Similarly, prematurity has been associated with suboptimal cardiovascular and lung development and an increased risk for heart failure and lung disease later in life.
However, “despite the large number of studies on prognostic factors for severe COVID-19, to our knowledge, no previous study has investigated the predictive role of early life events as a risk factor for severe COVID-19 in adulthood,” said the researchers.
What did the current study involve?
Crispi and colleagues hypothesized that low birth weight might increase the risk of severe COVID-19 among non-elderly adults.
To test this hypothesis, the researchers evaluated early life risk factors that are not usually considered in current clinical practices.
They analyzed a prospective cohort of 397 patients (aged 18 to 70 years) admitted to hospital with laboratory-confirmed SARS-CoV-2 infection, 60 (15%) of whom required admission to ICU.
Perinatal information and details of potentially predictive variables were collected for all patients.
On comparing the clinical characteristics of the 337 non-critically ill patients with the 60 patients who required ICU, the team found that the latter were more often older, more often male, and more likely to have a higher body mass index and high blood pressure.
Notably, the prevalence of low birth weight was also higher among ICU-treated individuals, compared with non-critically ill patients, at 18.3% versus 9.5%.
Multivariate analysis showed that those with a low birth weight had a 3.6 greater likelihood of being admitted to ICU than their counterparts with normal birth weight.
The results were reproduced in a validation cohort
To validate the results, the team conducted a web-based survey of 1,822 people (aged 18 to 70 years) who self-reported a laboratory-confirmed diagnosis of SARS-CoV-2.
Overall, 1,215 (67%) only experienced mild symptoms and did not require hospitalization, while 607 (33%) did require hospitalization, and 46 (8%) of those needed to be admitted to ICU.
On comparing the clinical characteristics of the 1,776 non-critically ill patients and those of the 46 ICU patients, the team again observed that the ICU patients were older, more often male, had a higher BMI and a greater prevalence of hypertension.
Notably, again, they also had a greater prevalence of low birth weight, at 26.1% versus 12.4%.
What are the implications of the study?
The team says the results suggest that a low birth weight increases the risk for severe COVID-19 among non-elderly adults.
“This new information further supports the importance of early life events in adult diseases and should be considered in future risk stratification algorithms,” they write.
“If confirmed that LBW [low birth weight] identifies high risk for complicated COVID-19, this should be included in the initial assessment of non-elder infected subjects and would offer opportunities for early interventions to prevent complications,” concludes the team.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.