Challenges in Studying Lung Development and Function
The study of lung development and function presents significant challenges due to the influence of various environmental factors such as first- and second-hand smoke, air pollution, and infections. Genetic factors also play a role. While retrospective studies can provide some insights, they often suffer from biases and inaccuracies related to environmental exposure recollections, which can skew results.
The Importance of Prospective Cohort Studies
To overcome these limitations, prospective cohort studies are essential. These studies recruit participants at a young age and follow their lung function over a lifetime, deliberately tracking environmental exposures. One of the oldest such cohorts in the United States, and globally, is the Tucson Children’s Respiratory Study (TCRS), which began between 1980 and 1984 with the recruitment of 1,246 healthy newborns in Tucson.
The TCRS conducted initial surveys at birth, followed by exams, surveys, and blood draws every 4 to 6 years starting at age six. “We have a comprehensive picture of the natural evolution of asthma in children who eventually developed the disease and a complete profile of factors that could be examined to determine their contribution to the likelihood of developing the disease over time,” explained Dr. Stefano Guerra, Ph.D., a professor of medicine and director of the Population Sciences Unit at the University of Arizona’s Asthma and Airway Disease Research Center.
Early Findings and Population Representation
The TCRS aimed to capture a snapshot of the general newborn population in Tucson at the time. Dr. Guerra emphasized the study’s value in drawing conclusions applicable to the general population, noting the significant representation of the Hispanic population (25%) but a smaller representation of African Americans (4%).
In a 1995 study, the cohort provided key insights into early childhood wheezing phenotypes. Researchers found that most children with wheezing had transient conditions related to reduced airway function at birth and were not at increased risk of asthma later in life. However, a significant minority had wheezing associated with a higher risk of asthma.
Prospective Value and Broader Implications
Prospective studies like the TCRS are invaluable because they link clinical information with disease development and outcomes in ways that retrospective analyses cannot. Dr. Guerra highlighted the variability and inconsistent data capture in retrospective studies, which also suffer from recall bias, where patients with a disease are more likely to remember childhood events as they search for potential causes.
Other respiratory cohorts, such as COPDGene, CARDIA, and the American Lung Association’s BELung cohort, also contribute valuable insights. These studies explore genetic clues, track respiratory and cardiovascular conditions, and examine lung health predictors in various populations.
Unique Contributions of the TCRS
The TCRS is one of the few cohorts that begin at birth, capturing critical early life stages. Dr. Guerra noted that while chronic obstructive pulmonary disease (COPD) was traditionally thought to develop in adulthood due to smoking, evidence suggests its roots extend to early childhood. The TCRS provides a window into this period, allowing researchers to examine early life data and relate risk factors to disease onset.
Up to half of COPD patients may have poor lung function from an early age. These “low-functioning” patients experience a natural decline in lung function with age, leading to COPD even without smoking. “Something happened in childhood, and the lungs didn’t develop as they should,” Dr. Guerra explained.
Biomarkers and Risk Factors
TCRS participants provide blood samples at each visit, offering researchers the opportunity to identify biomarkers that predict disease onset or progression. For instance, the protein CC16 is a potential biomarker, and TCRS studies have confirmed its relevance. “Individuals with low levels of this protein not only experience a more pronounced decline in lung function as adults but also have poor lung function growth in childhood,” Dr. Guerra noted.
Collaborations with other cohorts, such as the Swedish BAMSE and British MAAS, have validated these findings, revealing similar patterns and emphasizing the importance of early life factors in lung health.
Collaborative Efforts and Long-Term Impact
The collaborative network of cohorts strengthens findings by validating results across multiple studies, reducing the risk of false associations. Dr. Guerra emphasized the importance of distinguishing associations from causality, as confounding factors often coexist, such as smoking and excessive drinking.
Cohorts have revolutionized medical science, providing insights into disease development and prevention. The British Doctors Study, for example, established the causal link between smoking, lung cancer, and mortality, demonstrating the benefits of quitting smoking.
Conclusion and Future Directions
Longitudinal studies offer a comprehensive view of population health over time, distinguishing cause from effect more effectively than cross-sectional studies. Dr. David Mannino, a professor at the University of Kentucky, advocates for the long-term value of such studies, emphasizing their role in understanding and preventing diseases like asthma and COPD.
Dr. Guerra is a co-founder of Aspiro Therapeutics, developing treatments based on CC16. Dr. Melén has no relevant financial conflicts. Dr. Mannino advises several pharmaceutical companies and serves as an expert witness in tobacco and vaping industry lawsuits.
This content was originally published in the English edition of Medscape.
🔗 **Fuente:** https://espanol.medscape.com/verarticulo/5913764
