COPD Prevalence Increases With Age Among Young Patients

The prevalence of chronic obstructive pulmonary disease (COPD) among young patients increases with age, according to a study published in BMJ Open Respiratory Research.¹

Previous research shows that COPD could occur in young patients aged 20 to 50 years. The researchers of the present study noted a lack of data, especially large-scale population-based studies and longitudinal observations. Because of this, they investigated the demographic characteristics, prevalence, risk factors, and risk of all-cause mortality among young patients with COPD.

“It is necessary to accurately assess the characteristics and prognosis of COPD in young people, which may contribute to the early detection and intervention of COPD and thus reduce the health and socioeconomic burden of COPD,” the authors wrote.

To do so, the researchers used the National Health and Nutrition Examination Survey (NHANES) to create a study cohort representative of the US population. They chose patients inputted in NHANES from 2007 to 2012 who were aged 20 to 50 years and had data on pulmonary function test (PFT) results.

The researchers assessed 30,442 eligible participants found in NHANES from 2007 to 2012. Of the total, they chose 7784 participants aged 20 to 50 years who completed a PFT, 7654 of whom did not have COPD and 130 who had COPD. The researchers shaped their cohort to be more representative of the US population, making the weighted total participants 129,199,106; 2,124,077 patients had COPD and 127,075,029 did not have COPD. The researchers continued to acquire data about participants by passively following up until December 31, 2019.

Overall, the unweighted and weighted prevalences of COPD among patients aged 20 to 50 years were 1.67% and 1.64%, respectively. Across the age ranges, the COPD prevalences were 0.18%, 0.95%, 1.39%, 1.66%, 2.10%, and 3.65% for patients aged 20-25, 26-30, 31-35, 36-40, 41-45, and 46-50 years, respectively.

To better grasp the severity of airflow limitation within these young patients with COPD, the researchers utilized the Global Initiative for COPD (GOLD) classifications.² Patients with COPD classified as GOLD 1 have mild airflow limitation (FEV₁ ≥80% predicted), and those classified as GOLD 2 have moderate airflow limitation (50% ≤ FEV₁ <80% predicted). Also, patients classified as GOLD 3 have severe airflow limitation (30% ≤ FEV₁ <50% predicted), and those classified as GOLD 4 have very severe airflow limitation (FEV₁ <30% predicted).

The study showed that young patients with COPD were dominated by GOLD 1 and GOLD 2, meaning their severity of airflow was relatively mild.¹ Consequently, the researchers noted that patients may feel they do not have to go to the hospital due to their lack of symptoms, which may result in insufficient attention to COPD.

Similarly, the researchers found 12% of young patients with COPD had positive bronchodilator response (BDR). Because the proportion of positive BDR in patients with COPD is positively correlated with the severity of airflow limitation, the mild airflow limitation found in this population resulted in a low proportion of positive BDR.

As for gender, the researchers found higher COPD prevalence in male compared with females patients: 2.59% vs 0.72% (P < .001). This was supported by the COPD prevalence in participants between ages 46 and 50, as it reached a maximum of 5.85% in male patients and 1.46% in female patients. They associated this with male patients being linked to more serious smoking exposure, along with the high level of estrogen in young female patients that help reduce airflow restriction by stimulating alveolar regeneration and maintaining alveolar structure.

Through multivariate logistic regression, the researchers found multiple independent risk factors for young patients with COPD. They found that males (odds ratio [OR], 4.56; 95% CI, 2.74-7.61), non-Hispanic Black patients (OR, 2.77; 95% CI, 1.14-6.75), non-Hispanic White patients (OR, 4.93; 95% CI, 2.16-11.28), current smokers (OR, 2.36; 95% CI, 1.40-3.98), previous smokers (OR, 1.92; 95% CI, 1.05-3.51), and passive smokers (OR, 2.12; 95% CI, 1.41-3.20) are at higher risk of COPD.

This study showed that young patients with COPD had a higher risk of all-cause mortality than matched patients without COPD. Another recent study confirmed this, as it found that young patients with COPD “had a ninefold increased mortality risk compared with controls.”³

The researchers highlighted several limitations to their study findings, including that they did not research acute exacerbation events, which are important outcomes of COPD.¹ Also, they did not explore the relationships between young patients with COPD and their birth history, family history of respiratory disease, and history of respiratory disease in childhood due to the NHANES’s lack of data on these topics.

Based on both their findings and limitations, the researchers concluded that “early detection and intervention of COPD in young people may be of great significance and deserves further research.”

References

1. Wang Z, Li Y, Lin J, et al. Prevalence, risk factors, and mortality of COPD in young people in the USA: results from a population-based retrospective cohort. BMJ Open Respir Res. 2023;10(1):e001550. doi:10.1136/bmjresp-2022-001550
2. Chronic Obstructive Pulmonary Disease (COPD). BMJ Best Practice. Accessed July 19, 2023. https://bestpractice.bmj.com/topics/en-us/7/criteria#:~:text=GOLD%201%20%2D%20mild%3A%20FEV1%20%E2%89%A5,%3A%20FEV1%20%3C30%25%20predicted.
3. Divo MJ, Marin JM, Casanova C, et al; BODE Collaborative Group. Comorbidities and mortality risk in adults younger than 50 years of age with chronic obstructive pulmonary disease. Respir Res. 2022;23(1):267. doi:10.1186/s12931-022-02191-7