Prevalence, Medicaid use and mortality risk of low FEV₁in adults aged 20–35 years old in the USA: evidence from a population-based retrospective cohort study

Background The prevalence, Medicaid use and mortality risk associated with low forced expiratory volume in 1 s (FEV 1 ) among young adults aged 20–35 years are not well understood, despite its potential implications for the development of chronic pulmonary disease and overall prognosis. Methods A retrospective cohort study was conducted among young adults aged 20–35 years old, using data from the National Health and Nutrition Examination Survey, National Death Index and Centers for Medicare & Medicaid Services. Participants were categorised into a low FEV 1 group (pre-bronchodilator FEV 1 %pred <80%) and a normal FEV 1 group (FEV 1 %pred ≥80%). Weighted logistic regression analysis was employed to identify the risk factors associated with low FEV 1 , while Cox proportional hazard models were used to calculate the hazard ratio (HR) for Medicaid use and the all-cause mortality between the two groups. Results A total of 5346 participants aged 20–35 were included in the study, with 329 in the low FEV 1 group and 5017 in the normal group. The weighted prevalence of low FEV 1 among young adults was 7.1% (95% CI 6.0 to 8.2). Low body mass index (OR=3.06, 95% CI 1.79 to 5.24), doctor-diagnosed asthma (OR=2.25, 1.28 to 3.93), and wheezing or whistling (OR=1.57, 1.06 to 2.33) were identified as independent risk factors for low FEV 1 . Over a 15-year follow-up, individuals in the low FEV 1 group exhibited a higher likelihood of Medicaid use compared with those in the normal group (HR=1.73, 1.07 to 2.79). However, there was no statistically significant increase in the risk of all-cause mortality over a 30-year follow-up period (HR=1.48, 1.00 to 2.19). Conclusions A considerable portion of young adults demonstrated low FEV 1 levels, a characteristic that was associated with a higher risk of Medicaid use over a long-term follow-up, yet not linked to an augmented risk of all-cause mortality.