Background: Symptom severity is the largest factor in determining subjective health in COPD. Symptoms (eg, chronic cough, dyspnea) are associated with decreased health-related quality of life (HRQoL). We evaluated the impact of arformoterol on HRQoL in COPD patients, measured by St George's Respiratory Questionnaire (SGRQ). Post hoc growth mixture model (GMM) analysis examined symptom response profiles.
Methods: We examined data from a randomized, double-blind, parallel-group, 12-month safety trial of twice-daily nebulized arformoterol 15 µg (n=420) versus placebo (n=421). COPD severity was assessed by Global Initiative for Chronic Obstructive Lung Disease (GOLD) status. GMM analysis identified previously unknown patient subgroups and examined the heterogeneity in response to SGRQ Symptoms scores.
Results: SGRQ Total score improved by 4.24 points with arformoterol and 2.02 points with placebo (P=0.006). Significantly greater improvements occurred for arformoterol versus placebo in SGRQ Symptoms (6.34 vs 4.25, P=0.031) and Impacts (3.91 vs 0.97, P=0.001) scores, but not in Activity score (3.57 vs 1.75, P=0.057). GMM identified responders and nonresponders based on the SGRQ Symptoms score. End-of-study mean difference in SGRQ Symptoms scores between these latent classes was 20.7 points (P<0.001; 95% confidence interval: 17.6-23.9). Compared with nonresponders, responders were more likely current smokers (55.52% vs 44.02%, P=0.0021) and had more severe COPD (forced expiratory volume in 1 second [FEV1]: 1.16 vs 1.23 L, P=0.0419), more exacerbations (0.96 vs 0.69, P=0.0018), and worse mean SGRQ Total (59.81 vs 40.57, P<0.0001), Clinical COPD Questionnaire (3.29 vs 2.05, P<0.0001), and Modified Medical Research Council Dyspnea Scale (3.13 vs 2.75, P<0.0001) scores. Arformoterol-receiving responders exhibited significantly greater improvements in FEV1 (0.09 vs 0.008, P=0.03) and fewer hospitalizations (0.13 vs 0.24, P=0.02) than those receiving placebo.
Conclusion: In this study, arformoterol treatment significantly improved HRQoL reflected by SGRQ. For the analysis performed on these data, arformoterol may be particularly effective in improving lung function and reducing hospitalizations among patients who are unable to quit smoking or present with more severe symptoms.
Keywords: HRQoL; St George’s Respiratory Questionnaire; growth mixture model; long-acting beta agonist.