Correlating changes in lung function with patient outcomes in chronic obstructive pulmonary disease: a pooled analysis.
BACKGROUND
Relationships between improvements in lung function and other clinical outcomes in chronic obstructive pulmonary disease (COPD) are not documented extensively. We examined whether changes in trough forced expiratory volume in 1 second (FEV(1)) are correlated with changes in patient-reported outcomes.


METHODS
Pooled data from three indacaterol studies (n = 3313) were analysed. Means and responder rates for outcomes including change from baseline in Transition Dyspnoea Index (TDI), St. George's Respiratory Questionnaire (SGRQ) scores (at 12, 26 and 52 weeks), and COPD exacerbation frequency (rate/year) were tabulated across categories of ΔFEV(1). Also, generalised linear modelling was performed adjusting for covariates such as baseline severity and inhaled corticosteroid use.


RESULTS
With increasing positive ΔFEV(1), TDI and ΔSGRQ improved at all timepoints, exacerbation rate over the study duration declined (P < 0.001). Individual-level correlations were 0.03-0.18, but cohort-level correlations were 0.79-0.95. At 26 weeks, a 100 ml increase in FEV(1) was associated with improved TDI (0.46 units), ΔSGRQ (1.3-1.9 points) and exacerbation rate (12% decrease). Overall, adjustments for baseline covariates had little impact on the relationship between ΔFEV(1) and outcomes.


CONCLUSIONS
These results suggest that larger improvements in FEV(1) are likely to be associated with larger patient-reported benefits across a range of clinical outcomes.


BACKGROUND
ClinicalTrials.gov NCT00393458, NCT00463567, and NCT00624286.
Division of Clinical Science, St George's, University of London, London, UK. pjones@sgul.ac.uk
Paul W
PW
Jones
James F
JF
Donohue
Jerry
J
Nedelman
Steve
S
Pascoe
Gregory
G
Pinault
Cheryl
C
Lassen
D058666:Adrenergic beta-2 Receptor Agonists / Q000627:therapeutic use*; D000368:Aged; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D017326:Clinical Trials, Phase III as Topic; D019317:Evidence-Based Medicine; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007189:Indans / Q000627:therapeutic use*; D016014:Linear Models; D008168:Lung / Q000187:drug effects* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D015363:Quinolones / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D020127:Recovery of Function; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
D058666:Adrenergic beta-2 Receptor Agonists; D001993:Bronchodilator Agents; D007189:Indans; D015363:Quinolones; C510790:indacaterol