Annual change of respiratory functions in adult patients with asthma: the potential of antiasthma treatments for many years to repair irreversible changes of the airway.
BACKGROUND
Little is known regarding annual changes of respiratory functions among patients with asthma after asthma symptoms enter remission.


OBJECTIVE
Annual changes of respiratory function and influence of patient characteristics and treatment variables on these changes were assessed in patients with adult asthma.


METHODS
Respiratory function (pre- and postbronchodilator forced expiratory volume in one second [FEV₁] and reversibility by short-acting β₂-agonist) and their changes were retrospectively investigated and relationships between these changes, after symptomatic remission, and patient characteristics and treatments were analyzed in adult outpatients with asthma who had undergone spirometry (including a reversibility test) ≥5 times in >5 years.


RESULTS
In patients ≥40 years old, or with disease duration ≥10 years or receiving treatment for severe asthma (steps 4-5, high-dose inhaled glucocorticosteroids, or addition of other medications), both pre- and postbronchodilator FEV₁ values were significantly lower (p < .05). Mean annual change of prebronchodilator FEV₁ (Δpre-FEV₁), annual change of postbronchodilator FEV₁ (Δpost-FEV₁), and annual change of reversibility (Δ reversibility) were -13.8 ± 59.7 ml/year, -25.9 ± 51.0 ml/year, and -0.56% ± 1.89%/year, respectively. Multivariate analysis after stepwise selection for variables in patient characteristics or treatments showed that disease duration ≥10 years contributed to annual improvement of respiratory functions (Δpre-FEV₁: odds ratio [OR] 1.57, 95% confidence interval [CI] 1.01-2.46; Δpost-FEV₁: OR 2.13, 95% CI 1.25-3.66), treatment with long-acting β₂-agonists (LABAs) contributed to annual improvement of respiratory function (Δpre-FEV₁: OR 2.05, 95% CI 1.23-3.16; Δpost-FEV₁: OR 1.78, 95% CI 1.11-2.87), and poor compliance contributed to annual worsening of respiratory functions (Δpre-FEV₁: OR 0.43, 95% CI 0.24-0.76; Δpost-FEV₁: OR 0.39, 95% CI 0.22-0.70). In addition, duration of disease ≥10 years and severe treatment (steps 4-5) from the beginning contributed to decreasing Δreversibility (OR 0.55, 95% CI 0.34-0.87 and OR 0.50, 95% CI 0.29-0.83, respectively).


CONCLUSIONS
Long-term treatments for asthma are expected to normalize respiratory dysfunction, which cannot be repaired in the short term. Treatment with LABAs and patient compliance may be the most important factors associated with annual improvement of respiratory functions.
Muraki
Masato
M
Department of Respiratory Medicine and Allergology, Kinki University School of Medicine, Osakasayama, Osaka, Japan. muraki@ko-arena.med.kindai.ac.jp
Nisikawa
Yusaku
Y
Naito
Eri
E
Sato
Ryuji
R
Iwanaga
Takashi
T
Tohda
Yuji
Y
D058666:Adrenergic beta-2 Receptor Agonists / Q000627:therapeutic use; D000328:Adult; D000367:Age Factors; D000368:Aged; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology*; D003692:Delayed-Action Preparations; D005260:Female; D006801:Humans; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012737:Sex Factors; D013997:Time Factors
D058666:Adrenergic beta-2 Receptor Agonists; D018927:Anti-Asthmatic Agents; D003692:Delayed-Action Preparations