The natural history of preserved ratio impaired spirometry (PRISm), commonly characterized as FEV1/FVC lower limit of normal and FEV1 80% of projected value, is unknown. To investigate the natural history and long-term prognosis of the following PRISm trajectories: persistent PRISm trajectory (individuals with PRISm both young and middle-aged), normal to PRISm trajectory (individuals developing PRISm from normal spirometry in young adulthood), and PRISm to the normal course (individuals developing PRISm from normal spirometry in young adulthood), and PRISm to the normal route (individuals developing PRISm from normals (individuals recovering from PRISm in young adulthood by normalizing spirometry while middle-aged).
From 1976 to 1983, the Copenhagen City Heart Study tracked 1,160 people aged 20 to 40 years to establish their lung function trajectory; 72 had a persistent PRISm trajectory, 76 had a normal to PRISm trajectory, 155 had a PRISm to the normal course, and 857 had a normal period. Researchers tracked the risk of cardiopulmonary disease and death from 2001 to 2018.
There were 198 heart disease admissions, 143 pneumonia admissions, 64 chronic obstructive pulmonary disease admissions, and 171 deaths. Individuals with persistent PRISm trajectory had hazard ratios of 1.55 (95% CI, 0.91–2.65) for heart disease admission, 2.86 (1.70–4.83) for pneumonia admission, 6.57 (3.41–12.66) for chronic obstructive pulmonary disease admission, and 3.68 (2.38–5.68) for regular obstructive pulmonary disease admission when compared to those with normal trajectory.
Individuals on a normal PRISm trajectory had hazard ratios of 1.91 (1.24–2.95), 2.74 (1.70–4.42), 7.61 (4.21–13.72), and 2.96 (1.94–4.51), respectively. Individuals with PRISm to normal trajectory had the same prognosis as those with normal rotation.
PRISm is linked to an elevated risk of cardiopulmonary disease and all-cause mortality in middle-aged people. However, people who recover from PRISm in adulthood are no longer at risk.