COPD

Prematurity and smoking interact to increase COPD risk: Australian study


Very-to-moderate preterm birth almost trebles the risk of COPD at age 53 years, according to the latest data from the Tasmanian Longitudinal Health Study (TAHS).

The study, published in the Lancet Respiratory Medicine, confirms the multifactorial determinants of COPD – including early life exposures – beyond a history of smoking.

An analysis of 1,445 participants in the TAHS cohort identified that <4% were born very to moderate preterm (28-34 weeks gestational age), 12% late preterm (34-37 weeks), and 85% full term (at least 37 weeks).

Almost half (46%) were never smokers, 39% were past smokers and 15% were current smokers at the 53 year follow-up.

“After adjusting for sex, age, adult height, maternal age at birth, number of older siblings, maternal and paternal smoking, and family socioeconomic status in early life, very-to-moderate preterm birth was significantly associated with increased risk of COPD at age 53 years compared with term birth (odds ratio [OR] 2·9 [95% CI 1·1–7·7]).”

Very-to-moderate preterm birth was also significantly associated with poorer lung function – lower post-bronchodilator FEV1/FVC ratio, FEV1 , DLCO, and FEF 25–75%.

“FEV1 and FEV1/FVC ratio declined more rapidly between ages 45 years and 53 years in the very-to-moderate preterm group than in the term,” the study said.

It also found a significant interaction between very-to-moderate prematurity and current smoking status with the OR for COPD rising to 4.3.

“Our findings are consistent with observations that more extreme prematurity might interrupt normal lung development leading to structural and functional abnormalities,” the researchers said.

“These defects might persist into adulthood increasing the risk of airflow obstruction and COPD.”

They said the fact that late prematurity did not increase the risk of lung function deficits and COPD was reassuring given they represented the majority of preterm infants.

The finding was also consistent with the hypothesis that some late preterm infants might catch-up and normalise their lung function, while more severely preterm infants could not.

The researchers, including senior co-author Professor Shyamali Dharmage from the University of Melbourne’s Allergy & Lung Health Unit, said preventing prematurity and ongoing efforts at smoking prevention and cessation were warranted.

“The long-term impact of prematurity will impose an increasingly substantial burden on the health system as larger numbers of very to moderate preterm survivors reach their 50s and 60s in coming decades,” the study said.

“Preterm survivors should be specifically educated that their lungs are more likely to be affected by smoking and it should be especially discouraged through targeted health education in this high-risk group,” the study concluded.

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