Predictors of Low-Level Disease-Specific Knowledge in Patients with Chronic Obstructive Pulmonary Disease

Figures & data

Table 1 Baseline Characteristics of the Patients with COPD (n = 245)

Characteristic	Value
Sex (Male), n (%)	226 (92.2)
Age (years)	66.9±8.2
BMI (kg/m^2)	22.3±3.3
Smoking (pack years)	38.2±27.8
Nonsmoker, n (%)	22 (9.0)
Ex-smoker, n (%)	171 (69.8)
Current smoker, n (%)	52 (21.2)
Alcohol drinking, n (%)	77 (31.4)
Education level, n (%)
Basic (≤6 years)	83 (33.9)
Secondary (7–12 years)	136 (55.5)
Higher (≥13 years)	26 (10.6)
Monthly income (US$), n (%)
Very low (<1000)	145 (59.2)
Low (1000 to <2000)	43 (17.6)
Middle (2000 to<3000)	18 (7.3)
High (>3000)	39 (15.9)
Marital status, n (%)
Currently married	206 (84.1)
Single, divorced, widowed	39 (15.9)
Employment status, n (%)
Paid work	59 (24.1)
None	186 (75.9)
Dyspnea (mMRC scale), n (%)
Grade 0–1	120 (49.0)
Grade ≥ 2	125 (51.0)
Post-bronchodilator lung function
FEV1, L	1.6±0.6
FEV1, predicted %	60.6±22.8
FEV1/FVC ratio	55.1±14.0
GOLD severity stage, n (%)
Stage I, mild	53 (21.6)
Stage II, moderate	107 (43.7)
Stage III, severe	72(29.4)
Stage IV, very severe	13 (5.3)
6MWD (m)	345.9±84.2
Comorbidities, n (%)
Hypertension	54 (22.0)
Diabetes	20 (8.2)
Ischemic heart disease	3 (1.2)
Arthritis	9 (3.7)
Osteoporosis	8 (3.3)
Depression	2 (0.8)
SWLS	19.9±7.0
PRQ	70.5±15.5
SGRQ total	36.0±19.4
SF-36 PCS	48.1±8.9
SF-36 MCS	50.6±8.3
HADS-A	3.8±4.0
Prevalence of anxiety symptom^a, n (%)	38 (15.5)
HADS-D	6.4±4.1
Prevalence of depressive symptom^a, n (%)	92 (37.6)

Notes: Data are presented as mean±SD or n (%), unless otherwise indicated. ^a HADS-A or HADS-D score ≥8.

Abbreviations: BMI, body mass index; mMRC, modified Medical Research Council; FEV₁, forced expiratory volume in first second; FVC, forced vital capacity; 6MWD, 6-minute walk distance; SWLS, Satisfaction With Life Scale; PRQ, Personal Resource Questionnaire; SGRQ, St. George’s Respiratory Questionnaire; SF-36, Short Form 36 Health Survey Questionnaire; HADS-A, Hospital Anxiety and Depression Scale-Anxiety; HADS-D, Hospital Anxiety and Depression Scale-Depression.

Table 2 Disease Knowledge Scores According to the BCKQ

Topic	Mean	SD	Range (Min–Max)
Epidemiology	1.7	1.1	0.0–5.0
Etiology	2.9	1.2	1.0–5.0
Symptoms	3.1	1.1	0.0–5.0
Breathlessness	2.3	1.0	0.0–5.0
Phlegm	2.2	1.3	0.0–5.0
Infections	2.2	1.2	0.0–5.0
Exercise	3.1	1.1	0.0–5.0
Smoking	2.8	1.0	0.0–5.0
Vaccination	2.0	0.9	0.0–5.0
Inhaled bronchodilators	1.45	1.2	0.0–5.0
Antibiotics	2.4	1.4	0.0–5.0
Oral steroids	0.7	1.0	0.0–5.0
Inhaled steroids	0.6	0.9	0.0–4.0
Total score	28.1	7.4	5.0–46.0

Abbreviation: BCKQ, Bristol COPD Knowledge Questionnaire.

Table 3 Percentage of Patients Giving a Correct Response for All 65 Items Indexed by 13 Topics and Their Five Stems (a, b, c, d, e)

Q	Topic	a	b	c	d	e	Total (%)
1	Epidemiology	19.2 F	43.7 T	60.0 T	7.8 F	42.4 T	34.6
2	Etiology	63.7 T	78.8 T	62.0 T	46.5 F	40.4 F	58.2
3	Symptoms	49.4 F	63.3 T	22.0 T	45.3 F	53.5 F	46.7
4	Breathlessness	27.3 F	55.1 T	11.0 F	71.0 T	63.3 T	45.5
5	Phlegm	71.4 T	51.8 T	51.8 T	12.7 F	29.8 T	43.5
6	Infections	38.4 F	65.7 T	59.6 T	38.4 F	20.4 F	44.5
7	Exercise	79.6 T	69.8 F	73.9 T	79.2 T	5.3 F	61.5
8	Smoking	78.0 T	75.5 T	75.5 F	16.3 F	30.2 F	55.1
9	Vaccination	82.0 T	12.2 F	69.8 F	22.0 F	10.6 T	39.3
10	Inhaled bronchodilators	25.3 F	29.8 T	25.3 F	49.0 T	16.7 T	29.2
11	Antibiotics	28.6 F	62.9 T	49.8 F	32.2 F	64.5 T	47.6
12	Oral steroids	15.1 F	15.1 F	17.6 T	14.7 T	7.8 T	14.0
13	Inhaled steroids	19.6 F	6.1 F	18.8 T	11.0 F	4.1 F	11.9

Table 4 Correlation Between the Total BCKQ Score and Variables

Variables	Coefficient	Partial r	p value
Age	0.06	0.06	0.385
BMI	0.11	0.05	0.459
Smoking history (pack-years)		0.05	0.471
Current drinking, yes	0.10	0.01	0.930
Education
Basic (≤6 years)	-	-	-
Secondary (7–12 years)	2.13	0.12	0.054
Higher (≥13 years)	4.62	0.17	0.010
Income
Very low (<1000)	–	–	–
Low (1000 to <2000)	2.89	0.13	0.037
Middle (2000 to <3000)	−1.02	−0.03	0.607
High (>3000)	1.73	0.08	0.229
Marital status
Currently married	–	–	–
Single, divorced, widowed	−0.53	−0.02	0.707
Employment status
Paid work	–	–	–
None	0.04	0.01	0.974
mMRC
Grade 0–1	–	–	–
Grade ≥ 2	0.16	0.01	0.876
6MWD	−0.01	−0.07	0.263
Post-bronchodilator FEV1, % predicted	−0.08	−0.24	< 0.001
Post-bronchodilator FEV1/FVC	−0.07	−0.13	0.044
History of hypertension	−0.37	−0.02	0.767
History of diabetes	1.01	0.03	0.589
SWLS	0.17	0.15	0.020
PRQ	0.08	0.16	0.012
SGRQ total	0.04	0.09	0.170
SF-36 MCS	0.12	0.13	0.045
SF-36 PCS	0.04	0.04	0.525
HADS-A	−0.35	−0.17	0.006
HADS-D	−0.53	−0.28	< 0.001

Abbreviations: BCKQ, Bristol COPD Knowledge Questionnaire; CI, confidence interval; BMI, body mass index; mMRC, modified Medical Research Council; 6MWD, 6-minute walk distance; FEV₁, forced expiratory volume in first second; FVC, forced vital capacity; SWLS, Satisfaction With Life Scale; PRQ, Personal Resource Questionnaire; SGRQ, St. George’s Respiratory Questionnaire; SF-36, Short Form 36 Health Survey Questionnaire; PCS, physical component summary; MCS, mental component summary; HADS-A, Hospital Anxiety and Depression Scale-Anxiety; HADS-D, Hospital Anxiety and Depression Scale-Depression.

Figure 1 The total BCKQ score according to the disease severity (GOLD stage).

Table 5 Multivariate Analysis of the Factors Associated with the Total BCKQ Score

Variables	Adjusted Coefficient	Partial r	P value
Post-bronchodilator FEV1, % predicted	−0.08	−0.25	<0.001
HADS-D	−0.53	−0.29	<0.001
	No. of observations 245, R^2-adjusted 0.1280

Abbreviations: BCKQ, Bristol COPD Knowledge Questionnaire; FEV₁, forced expiratory volume in first second; HADS-D, Hospital Anxiety and Depression Scale-Depression.