. 2016 Jul;13(7):1016–1025. doi: 10.1513/AnnalsATS.201512-800OC

Table 1.

Clinical and physiological characteristics of each group

	Persistent Chronic Bronchitis– (n = 1,342)	Resolved Chronic Bronchitis (n = 162)	New Chronic Bronchitis (n = 136)	Persistent Chronic Bronchitis+ (n = 135)	P Value
Age at current visit, yr	66.23 ± 8.93	65.37 ± 8.77	65.73 ± 9.46	65.42 ± 8.46	0.500
Race, % white	70.6^*	73.5	72.8	78.5	0.235
Sex, % male	49.1^*^†^‡	59.9	57.4	58.5	0.007
BMI, kg/m²	28.31 ± 6.11	29.04 ± 6.04	28.85 ± 5.84	28.57 ± 6.76	0.423
Smoking status
Current smoking (phase 2), %	31.2^*^‡	37.1^*	45.6	53.4	<0.0001
Persistent ex-smokers, %	58.6^*^†^‡	39.5	45.6	37.8	<0.0001
Resumed smokers, %	2.3^‡	1.9^‡	6.6^*	1.5	<0.0001
Quitters, %	10.1^†	23.5^*^‡	8.8	8.9	<0.0001
Persistent current smokers, %	28.9^*^†^‡	35.2^*	39.0^*	51.9	<0.0001
Smoking history, pack-years	43.34 ± 22.72^*^‡	47.84 ± 21.48^*	51.42 ± 31.25	57.17 ± 28.75	<0.0001
FEV₁% pred	79.91 ± 26.07^*^†^‡	67.57 ± 25.72	66.16 ± 27.57	63.20 ± 25.03	<0.0001
FVC% pred	89.74 ± 18.12^*^†^‡	83.08 ± 17.78	81.96 ± 19.43	83.18 ± 17.44	<0.0001
FEV₁/FVC	66.40 ± 15.76^*^†^‡	60.39 ± 16.95	59.38 ± 17.37	56.45 ± 16.82	<0.0001
6-Min walk distance, ft	1,339.8 ± 421.7^*^†^‡	1,191.4 ± 411.32	1,127.3 ± 475.35	1,164.8 ± 414.05	<0.0001
MMRC dyspnea score	0 (0–2)^*^†^‡	2 (0–3)^*	2 (0–3)	2 (1–3)	<0.0001
SGRQ score	12.5 (3.5–30.5)^*^†^‡	30.3 (16.2–47.5)^*^‡	38.3 (21.2–53.2)	45.3 (29.6–61.0)	<0.0001
CAT score	8 (4–15)^*^†^‡	16 (8–22)^*^‡	18 (12.5–24)	20 (14–26)	<0.0001
HADS anxiety score	4 (2–6)^*^†	5 (2–8)	4 (2–8)	5 (2–7)	<0.0001
HADS depression score	4 (2–6)^*^†^‡	3 (2–6)	4 (2–7)	4 (2–8)	<0.0001
BODE Index	0 (0–2)^*^†^‡	1 (0–3)	2 (0–3)	2 (1–4)	<0.0001
Exacerbation frequency, No./patient/yr	0 (0–0)^*^†^‡	0 (0–1)	0 (0–0)^*	0 (0–1)	<0.0001
History of severe exac, %	7.2^*^†^‡	14.2	14.0	17.0	<0.0001
History of asthma, %	16.0^*^†^‡	27.2	18.4	22.2	<0.0001
Gastroesophageal reflux, %	28.6^*^†	36.4	35.3	38.5	0.015
Noct awake cough, %	12.4^*^†^‡	19.8^*^‡	43.4^*	54.8	<0.0001
Noct awake SOB, %	9.8^*^†^‡	20.4^*^‡	29.4	37.8	<0.0001
Longitudinal changes, phase 1 – phase 2
Absolute change FEV₁, ml	−208.72 ± 262.38	−227.46 ± 302.32	−266.96 ± 334.22	−236.41 ± 324.02	0.090
Percent change FEV₁% pred	−2.15 ± 9.85	−3.84 ± 10.67	−4.55 ± 11.74	−3.53 ± 10.46	0.011
FEV₁ annual decline, ml/yr	−39.20 ± 49.42	−42.90 ± 57.80	−49.93 ± 64.80	−44.60 ± 61.58	0.098
Change in MMRC score	0.03 ± 1.14^‡	−0.09 ± 1.35^‡	0.51 ± 1.45^*	0.12 ± 1.20	<0.0001
Change in SGRQ	0.17 ± 13.93^†^‡	−4.26 ± 17.93^*^‡	9.37 ± 17.77^*	2.06 ± 16.28	<0.0001
Change in 6-min walk distance, ft	−100.56 ± 353.76	−126.82 ± 358.46	−183.18 ± 386.23	−115.57 ± 359.50	0.007

Definition of abbreviations: BMI = body mass index; BODE = body mass index, airflow obstruction, dyspnea, and exercise capacity; CAT = COPD Assessment Test; exac = exacerbation; FEV₁% pred = FEV₁ expressed as a percentage of the predicted value; FVC% pred = FVC expressed as a percentage of the predicted value; HADS = Hospital Anxiety and Depression Scale; MMRC = Modified Medical Research Council; Noct = nocturnal; 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; SOB = shortness of breath.

Values are expressed as means ± SD or as medians (interquartile range).

P < 0.05 compared with resolved chronic bronchitis.

^{^†}

P < 0.05 compared with new chronic bronchitis.

^{^‡}

P < 0.05 compared with persistent chronic bronchitis+.