Table 2.
Multivariable linear regression for continuous outcomes by chronic bronchitis group*
| Resolved Chronic Bronchitis vs. Persistent Chronic Bronchitis– |
New Chronic Bronchitis vs. Persistent Chronic Bronchitis– |
Persistent Chronic Bronchitis+ vs. Persistent Chronic Bronchitis– |
||||
|---|---|---|---|---|---|---|
| Outcome | β-Coefficient (95% CI) | P Value | β-Coefficient (95% CI) | P Value | β-Coefficient (95% CI) | P Value |
| MMRC dyspnea score | 0.27 (0.07 to 0.47) | 0.0044 | 0.62 (0.42 to 0.82) | <0.0001 | 0.76 (0.54 to 0.98) | <0.0001 |
| 6-MWD, ft | −84.04 (–144.82 to –23.26) | 0.0068 | −136.10 (–201.72 to 70.48) | <0.0001 | −87.56 (–153.96 to 21.16) | <0.0001 |
| SGRQ score | 8.55 (5.86 to 11.23) | <0.0001 | 14.50 (11.62 to 17.38) | <0.0001 | 20.15 (17.21 to 23.09) | <0.0001 |
| CAT score | 4.21 (3.05 to 5.37) | <0.0001 | 6.90 (5.65 to 8.15) | <0.0001 | 8.60 (7.32 to 9.87) | <0.0001 |
| HADS-A score | 0.98 (0.40 to 1.56) | 0.0009 | 0.76 (0.13 to 1.38) | 0.017 | 1.09 (0.46 to 1.72) | 0.0008 |
| HADS-D score | 0.75 (0.26 to 1.24) | 0.003 | 0.97 (0.44 to 1.50) | 0.0003 | 1.5 (0.95 to 2.05) | <0.0001 |
| Exacerbation frequency, no./patient/yr | 0.26 (0.14 to 0.38) | <0.0001 | 0.13 (–0.01 to 0.27) | 0.066 | 0.46 (0.32 to 0.60) | <0.0001 |
| Change in MMRC | −0.19 (–0.39 to 0.01) | 0.062 | 0.44 (0.22 to 0.66) | <0.0001 | 0.03 (–0.19 to 0.25) | 0.81 |
| Change in SGRQ | −4.67 (–7.14 to –2.20) | 0.0002 | 8.78 (6.11 to 11.45) | <0.0001 | 1.46 (–1.24 to 4.16) | 0.82 |
| Change in 6-MWD, ft | −7.30 (–65.98 to 51.38) | 0.8100 | −66.6 (–130.42 to –3.06) | 0.0400 | −60.80 (–125.01 to 3.49) | 0.064 |
Definition of abbreviations: 6-MWD = 6-minute walk distance; CAT = COPD Assessment Test; CI = confidence interval; HADS-A = Hospital Anxiety and Depression Scale-Anxiety score; HADS-D = Hospital Anxiety and Depression Scale-Depression score; MMRC = Modified Medical Research Council; persistent chronic bronchitis+ = subjects positive at phase 1/positive at phase 2 for chronic bronchitis; persistent chronic bronchitis– = subjects negative at phase 1/negative at phase 2 for chronic bronchitis; SGRQ = St. George’s Respiratory Questionnaire.
Entries in boldface indicate a significant difference.
*
Age, race, sex, FEV1% predicted, and smoking status as covariates.