Quantifying and Characterizing COPD Symptom-defined Exacerbation Recovery using the EXAcerbations of Chronic pulmonary disease Tool (EXACT)
Open AccessQuantifying and Characterizing COPD Symptom-defined Exacerbation Recovery using the EXAcerbations of Chronic pulmonary disease Tool (EXACT)Background: Exacerbations can be debilitating to patients with chronic obstructive pulmonary disease (COPD). Recovery from symptom-defined exacerbation events is poorly characterized. Purpose: To evaluate short-term effects of symptom-defined exacerbation recovery on health status and pulmonary function in patients with moderate to severe COPD and identify factors associated with time to recovery. Methods: Secondary analyses of pooled data from two 12-week phase II international randomized controlled trials using the EXAcerbations of Chronic Pulmonary Disease Tool (EXACT) to identify symptom-defined events were conducted. Recovery was classified as recovered, persistent worsening or censored. Multiple regression analyses were used to test the effect of symptom-defined recovery status on change in health status using the St. George’s Respiratory Questionnaire (SGRQ) and forced expiratory volume in one second (FEV1) from baseline to Week 12.Baseline indicators of recovery were identified using a multivariate Cox proportional hazards model. Multiple logistic regression was used to identify baseline indicators for patients with recovery (≤ day 10) vs. persistent worsening.A latent class analysis was conducted to identify subgroups of patients with distinct disease severity based on age, FEV1, comorbid conditions, rescue medication, SGRQ, and respiratory symptoms. The proportion of patients classified by symptom-defined event recovery type was evaluated across subgroups.Results: Of 1,346 eligible patients, 414 (31%) experienced at least one symptom-defined event, and were predominantly male (72.7%) with a mean (SD) age of 61.8 (8.01) years and FEV1 % predicted of 55.8 (14.68). In the multiple regression analysis, recovery status was not a significant indicator of change in lung function. Recovery status and baseline SGRQ were significant indicators of change in health status (p=0.04; p<0.01). Post-hoc analyses showed significant group differences in respiratory symptom severity from baseline to week 12 (p<0.01).Baseline factors explaining reduced recovery time included increased number of reported comorbid conditions (HR =1.07, 95% CI 1.00 – 10.14) and mean number of rescue medication puffs/day (HR =1.07, 95% CI 1.01 – 1.14). Baseline factors associated with recovering ≤ 10 days included increased number of comorbid conditions (OR =1.27, 95% CI 1.06 – 1.53), higher EXACT score (OR = 1.08, 95% CI 1.04 – 1.12), and lower SGRQ score (OR =0.98, 95% CI 0.96 -0.99).Three subgroups were identified. The largest (61%) was “moderate”; characterized by moderate lung function impairment, comorbid conditions, rescue medication utilization, and symptom levels. The second (37%) was “severe”; characterized by more severe lung function impairment, same mean number of comorbid conditions, increased rescue medication, and higher symptom levels compared to moderate. The third (2%) was “very severe”; characterized by very severe lung function impairment, increased mean number of comorbid conditions, greatly increased rescue medication, and higher symptom levels compared to moderate. Subgroups weren’t associated with recovery. Conclusions: For a subset of moderate to severe COPD patients who experience symptom-defined exacerbations, these events signal deterioration in their COPD, with significant worsening of respiratory symptoms and health status. Patients with a greater number of comorbid conditions and higher levels of baseline symptoms had shorter recovery duration. Moderate, severe, and very severe disease subgroups weren’t associated with recovery.
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