Lung capacity starts to decline much earlier than previously though: study

Contrary to long-held belief, lung capacity does not plateau and stay stable until the age of 40. Rather, it begins to decline in the early 20s, immediately after reaching its peak.This discovery overturns previous models of the evolution of respiratory capacity with age. “Contrary to some preconceptions, we found no evidence of a plateau after reaching peak lung development, even in non-smoking, asthma-free individuals,” reported researchers in the Lancet Respiratory Medicine.Their accelerated cohort study, using data from 30,438 patients ages four to 80, showed that lung function would develop in two distinct phases: a very rapid first phase during childhood and early adolescence, followed by a slower second phase until the early 20s.This trajectory was established using the results of the participants' forced expiratory volume in one second (FEV1) and forced vital capacity (FVC).Women and men differentialsIn women, FEV1 increased by an average of 234 (95% CI 223-245) mL per year until the age of 13, then by 99 (95% CI 76-122) mL per year until the age of 20, when it peaked. Thereafter, it immediately began to decline by 26 (95% CI -27 -25) mL per year.In men, FEV1 increased by 271 (95% CI 263-280) mL per year up to age 16, then more slowly (108 [95% CI 93-124] mL/year) until around age 23. A period of decline would then begin at a rate of -38 (95% CI -39 -37) mL/year.VC followed much the same rhythm as FEV1, peaking at age 20 in women and 23 in men. In contrast, the decline in FVC occurred in two phases: a slower decline until the age of 42 (-22 mL/year), followed by a more rapid decline of around -42 mL/year.“The accelerated growth in lung function from the age of four, and the absence of a plateau in early adulthood, suggest that the risk of chronic respiratory disease in adulthood is strongly influenced by the attainment of a peak in lung function,” said the researchers from a Spanish-Australian collaboration.Asthma and smokingThe peak in lung function development was reached earlier in asthmatic individuals. In both sexes, individuals with persistent asthma reached peak FEV1 at around 17 years of age, three years earlier than non-asthmatic women and six years earlier than non-asthmatic men. The FVC of asthmatic women peaked at age 18 and remained lower throughout life than that of women without asthma. This effect was not observed in men. As for smokers, smoking was associated with an accelerated decline in FEV1 from their mid-30s, in both sexes. “This underscores the importance of using spirometry at an early age to identify at-risk individuals from infancy through to early adulthood, in order to promote the growth of lung function and avoid a too-early peak in lung function,” concluded the researchers.This article has been translated from its original French and first appeared on our sister site Profession Santé.

Lung capacity starts to decline much earlier than previously though: study

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