Association of respiratory symptom profiles with future exacerbations and lung function decline in mild-to-moderate COPD.

BACKGROUND

The prognostic value of respiratory symptom profiles for predicting exacerbation risk and lung function decline remains unclear in mild-to-moderate chronic obstructive pulmonary disease (COPD).

RESEARCH QUESTION: Are respiratory symptom profiles associated with both exacerbation risk and lung function decline in mild-to-moderate COPD?

STUDY DESIGN AND

METHODS

This was a posthoc analysis of data from participants with mild-to-moderate COPD from the SubPopulations and InteRmediate Outcome Measures in COPD Study. Respiratory symptom profiles were identified through latent class analysis. Outcomes included exacerbation rates evaluated by zero-inflated negative binomial regressions, time-to-first exacerbation evaluated by Cox regression and longitudinal forced expiratory volume in 1 second (FEV1) decline evaluated by linear mixed-effects models.

RESULTS

Among the 954 participants with mild-to-moderate COPD, five distinct respiratory symptom profiles were identified. Compared with the 'minimal respiratory' profile, the 'productive cough' profile was associated with a higher rate of any respiratory exacerbations (relative ratio [RR] 1.84; 95% confidence interval [CI] 1.29 to 2.64) and severe respiratory exacerbations (RR 2.05; 95% CI 1.12 to 3.74). Similarly, the 'Wheeze' profile was associated with higher rates of any (RR 1.55; 95% CI 1.12 to 2.15) and severe exacerbations (RR 1.73; 95% CI 1.00 to 2.98). The 'nearly all respiratory symptoms' profile was associated with a higher rate of exacerbations (any exacerbation: RR 2.12; 95% CI 1.56 to 2.89; severe exacerbations: RR 2.07; 1.23 to 3.47) and an accelerated annual FEV1 decline (-15.41 mL/year; 95% CI -30.33 to -0.51 mL/year). The 'dry cough' profile exhibited the lowest FEV1 trajectory despite a non-significant annual decline.

INTERPRETATION: Respiratory symptom profiles identifies distinct prognostic outcomes in mild-to-moderate COPD. The productive cough is associated with increased exacerbation risk, while the dry cough is associated with a lower lung function trajectory.

TRIAL REGISTRATION NUMBER: NCT0196934.