Chronic obstructive pulmonary disease and a new phenotype of lung function impairment predicted progression of frailty in older adults, based on data from more than 5000 individuals.
COPD has been associated with frailty, but longitudinal data on the association of COPD with progression of frailty are limited, as are data on the potential association of preserved ratio impaired spirometry (PRISm) with frailty progression, wrote Di He, BS, of Zhejiang University School of Medicine, China, and colleagues.
PRISm has been defined in recent studies as "proportional impairments in FEV1 and FVC, resulting in the normal ratio of FEV1 and FVC." Individuals with PRISm may transition to normal spirometry or COPD over time, the researchers wrote.
In a study published last month in the journal Chest, the researchers reviewed data from 5901 adults aged 50 years and older who were participating on the English Longitudinal Study of Ageing (ELSA), a prospective cohort study. Of these, 3765 were included in an additional analysis of the association between transitions from normal spirometry to PRISm and the progression of frailty. The mean age of the participants was 65.5 years; 54.9% were women.
The median follow-up period for analysis with frailty progression was 9.5 years for PRISm and COPD and 5.8 years for PRISm transitions. Lung function data were collected at baseline. Based on spirometry data, participants were divided into three lung function groups — normal spirometry, PRISm, and COPD — and each of these was classified based on severity. Frailty was assessed using the frailty index (FI) during the follow-up period.
Frailty progression based on FI was significantly accelerated in patients with PRISm and COPD compared with individuals with normal spirometry, with additional annual increases of 0.301 and 0.172, respectively (P < .001 for both).
When stratified by severity, individuals with more severe PRISm and with more COPD had higher baseline FI and faster FI progression compared with those with mild PRISm and COPD.
PRISm transitions were assessed over a 4-year interval at the start of the ELSA. Individuals with normal spirometry who transitioned to PRISm during the study had accelerated progression of frailty, as did those with COPD who transitioned to PRISm. However, no significant frailty progression occurred in those who changed from PRISm to normal spirometry.
The mechanisms behind the associations of PRISm and COPD with frailty remain unclear, but the results were consistent after controlling for multiple confounders, "suggesting PRISm and COPD had independent pathophysiological mechanisms for frailty," the researchers write in their discussion. Other recent studies have identified sarcopenia as a complication for individuals with lung function impairment, they noted. "Therefore, another plausible explanation could be that PRISm and COPD caused sarcopenia, which accelerated frailty progression," they say.
The findings were limited by several factors, including the observational design and the potential underestimation of lung function in participants with reversible airflow obstruction because of the use of prebronchodilator spirometry in the cohort study, the researchers noted.
However, the results were strengthened by the large sample size and high-quality data from the ELSA, and by the repeat measures of FI and lung function. The results were consistent after controlling for multiple confounders, and support the need for more research to explore the causality behind the association of PRISm and COPD with frailty, the researchers concluded.
The study was supported by the Zhejiang Provincial Basic Public Welfare Research Project, the Zhoushan Science and Technology Project, and the Key Laboratory of Intelligent Preventive Medicine of Zhejiang Province. The researchers report no relevant financial relationships.
Chest. Published online July 25, 2023. Full text