Lung Function Decline in Adult Asthmatics—A 10-Year Follow-Up Retrospective and Prospective Study

Asthma may have an impact on lung function decline but conflicting results are reported in forced expiratory volume in one second (FEV1) decline. We aimed to describe the changes in FEV1 in lifelong non-smoking adult asthmatic outpatients during a 10-year follow-up comparing years 1–5 (1st period) with years 6–10 (2nd period) to assess factors affecting these changes. A total of 100 outpatients performed spirometry every 3 months during a 10-year survey. FEV1/Ht3 slope values of the 2nd period reduced significantly respect to the 1st period (p < 0.0001). FEV1 slopes of years 1–5 and 6–10 were inversely associated with FEV1 at enrolment (p = 0.02, p = 0.01, respectively). Reversibility and variability FEV1 showed a significant effect on the 1st period slopes (p = 0.01 and p < 0.04, respectively). Frequent exacerbators in the 1st year had steeper FEV1/Ht3 slopes in the 1st period (p = 0.01). The number of subjects using higher doses of ICS was significantly lower at the 10th years respect to the 5th and the 1st year (p < 0.001, p = 0.003, respectively). This study shows that FEV1 decline in treated adult asthmatics non-smokers, over 10-year follow-up, is not constant. In particular, it slows down over time, and is influenced by FEV1 at enrolment, reversibility, variability FEV1 and exacerbation score in the 1st year.