Dyspnoea and symptom burden in mild–moderate COPD: the Canadian Cohort Obstructive Lung Disease Study

Prevalence and severity of dyspnoea (Medical Research Council (MRC)) (a), and health-related quality of life (COPD Assessment Test (CAT) total score (b); SGRQ total score (c) at baseline. Error bars represent quartiles 1 and 3. Values above the bars in panel (a) represent the mean±sd MRC dyspnoea scores for each group. CAT: COPD Assessment Test; COPD: chronic obstructive pulmonary disease; GOLD: Global Initiative for Chronic Obstructive Lung Disease; MRC: Medical Research Council; SGRQ: St George's Respiratory Questionnaire. ^#: significantly different from each other after Tukey adjustment for multiple comparisons (p<0.05).

Odds ratios of dyspnoea severity for: a) MRC 2 versus MRC 1 and b) MRC ≥3 versus MRC 1. MRC was measured at baseline for comparisons by sex and physician diagnosis of COPD, and at Visit 3 for comparisons by exacerbation history. ^#: For analysis by exacerbation status, n were as follows: COPD: n=467; mild-COPD (GOLD 1): n=282; moderate-COPD (GOLD 2): n=185. Adjusted OR were obtained by performing multivariate multinomial logistic regression models, adjusted for sex, age, BMI, smoking history, cardiovascular comorbidities, and other respiratory comorbidities. For women versus men comparisons, sex was not included as a covariate. For smokers versus never-smokers, smoking history was not included as a covariate. To estimate the association between exacerbations and MRC, exacerbations were observed in preceding 12 months at Visit 3. BMI: body mass index; COPD: chronic obstructive pulmonary disease; GOLD: Global Initiative for Chronic Obstructive Lung Disease; MRC: Medical Research Council.

Adjusted β of health-related quality of life for: a) CAT and b) SGRQ. CAT and SGRQ were measured at baseline for comparisons by sex and physician diagnosis of COPD, and at Visit 3 for comparisons by exacerbation history. ^#: For analysis by exacerbation status, n were as follows: COPD: n=467; mild-COPD (GOLD 1): n=282; moderate-COPD (GOLD 2): n=185. Adjusted β were obtained by performing multivariate linear regression models, adjusted for sex, age, BMI, smoking history, cardiovascular comorbidities and other respiratory comorbidities. For women versus men comparisons, sex was not included as a covariate. For smokers versus never-smokers, smoking history was not included as a covariate. To estimate the association between exacerbations and CAT or SGRQ, exacerbations were observed in preceding 12 months at Visit 3. BMI: body mass index; CAT: COPD Assessment Test; COPD: chronic obstructive pulmonary disease; GOLD: Global Initiative for Chronic Obstructive Lung Disease; SGRQ: St George's Respiratory Questionnaire.

Dyspnoea severity for people with COPD by: a) sex, b) the presence of a physician diagnosis of COPD, and c) exacerbation frequency. MRC was measured at baseline for comparisons by sex and physician diagnosis of COPD, and at Visit 3 for comparisons by exacerbation history. Values above the bars represent the mean±sd MRC dyspnoea scores for each group. ^#: Significantly different (p<0.001). p-values were obtained by performing Chi-squared or Fisher's exact test for category variables. For continuous variables, p-values were obtained by t-test (normal distribution) or Mann–Whitney U-test (not normal distribution) for sex and physician diagnosis subgroups. ANOVA (normal distribution) or Kruskal–Wallis test (not normal distribution) were performed for exacerbation subgroups. Analysis of variance subgroup comparisons of mean±sd differences by sex, presence of a physician diagnosis of COPD, and exacerbation frequency were all significant (p<0.001). COPD: chronic obstructive pulmonary disease; MRC: Medical Research Council.