Prevalence and Characteristics of Undiagnosed COPD in Adults 40 Years and Older – Reports from the Tunisian Population-Based Burden of Obstructive Lung Disease Study

Figures & data

Figure 1. Identification of chronic obstructive pulmonary disease subjects with and without a previous diagnosis of COPD.

Table 1. Sociodemographic characteristics of the study population.

	Total 661 (100%)	With COPD 35 (5.3%)	Without COPD 626 (94.7%)	P-value
Sex, n (%)				<0.001
Female	352 (53.3)	6 (17.1)	346 (55.3)
Male	309 (46.7)	29 (82.9)	280 (44.7)
Age, years Median (IQR)	52 (46-58)	58 (55-66)	52 (45-58)	<0.001
Age range, n (%)
40–49 years	249 (37.6)	3 (8.6)	246 (39.3)	<0.001
50–59 years	271 (40.9)	16 (45.7)	255 (40.7)
60–69 years	105 (15.9)	9 (25.7)	96 (15.3)
≥70 years	36 (5.4)	7 (20)	29 (4.6)
BMI (kg/m^2; mean ± SD)	29.4 ± 7.8	26.2 ± 5.8	29.6 ± 7.9	0.038
BMI (kg/m^2, n (%))
<20 kg/m^2	24 (3.6)	6 (17.1)	18 (2.9)	<0.001
20–25 kg/m^2	129 (19.5)	10 (28.6)	119 (19.0)
25–30 kg/m^2	236 (35.7)	7 (20.0)	229 (36.6)
30–35 kg/m^2	167 (25.3)	9 (25.7)	158 (25.2)
>35 kg/m^2	105 (15.9)	3 (8.6)	102 (16.3)
Education, n (%)				0.580
Illiterate	102 (15.4)	7 (20.0)	95 (15.2)
Primary	72 (10.9)	3 (8.6)	69 (11.0)
Middle school	187 (28.3)	8 (22.9)	179 (28.6)
High school	99 (15.0)	8 (22.9)	91 (14.5)
University or above	201 (3.04)	9 (25.7)	192 (30.7)
Occupation, n (%)				<0.001
Unemployed	264 (40.0)	9 (25.7)	255 (40.7)
Working	271 (41.0)	9 (25.7)	262 (41.9)
Retired	126 (19.0)	17 (48.6)	109 (17.4)
Worked in a high risk occupation, n (%)	380 (57.5)	26 (74.3)	354 (56.5)	0.027
Economic classification, n (%)				0.407
Low	15 (2.3)	1 (2.9)	14 (2.2)
Medium	616 (93.2)	34 (97.1)	582 (93)
High	30 (4.5)	0 (0.0)	30 (4.8)
Smoking status, n (%)				<0.001
Never smoker	398 (60.2)	8 (22.9)	390 (62.3)
Smoker	176 (26.6)	19 (54.3)	157 (25.1)
Ex-smoker	87 (13.2)	8 (22.9)	79 (12.6)
Previous spirometry, n (%)	80 (12.1)	14 (40.0)	66 (10.5)	<0.001
Family history of COPD, n (%)	42 (6.4)	1 (2.9)	41 (6.5)	0.718

P value represents comparison between subjects with and without COPD. Independent t-test, Mann Withney U-test, Fisher’s exact test, or χ², were used as appropriate. Abbreviations: COPD, Chronic obstructive pulmonary disease; BMI, Body mass index.

Table 2. Sociodemographic characteristics of subjects with and without previous diagnosis of COPD.

	Undiagnosed COPD 28 (80%)	Diagnosed COPD 7 (20%)	P-value
Sex, n (%)			0.232
Female	6 (21.4)	0 (0.0)
Male	22 (78.6)	7 (100)
Age, years Median (IQR)	58 (53-66)	64 (57-75)	0.256
BMI (kg/m^2; mean ± SD)	26.6 ± 6.0	24.0 ± 3.7	0.356
BMI (kg/m^2, n (%))			0.231
<25 kg/m^2	14 (50.0)	2 (28.6)
25-29.9 kg/m^2	4 (14.3)	3 (42.9)
≥30 kg/m^2	10 (35.7)	2 (28.6)
Education, n (%)			0.025
Illiterate	5 (17.9)	2 (28.6)
Primary	9 (32.1)	2 (28.6)
Middle school	3 (10.7)	1 (14.3)
High school	11 (39.3)	0 (0.0)
University or above	0 (0.0)	2 (28.6)
Occupation, n (%)			0.739
Unemployed	7 (25.0)	2 (28.6)
Working	8 (28.6)	1 (14.3)
Retired	13 (46.4)	4 (57.1)
Worked in a high risk occupation, n (%)	21 (75.0)	5 (71.4)	0.847
Economic classification, n (%)			0.612
Low	1 (3.6)	0 (0.0)
Medium	27 (96.4)	7 (100.0)
High	0 (0.0)	0 (0.0)
Smoking status, n (%)			0.811
Never smoker	7 (25.0)	1 (14.3)
Smoker	15 (53.6)	4 (57.1)
Ex-smoker	6 (21.4)	2 (28.6)
Family history of COPD, n (%)	1 (3.6)	0 (0.0)	0.800

P value represents comparison between undiagnosed and diagnosed subjects with COPD. Independent t-test, Mann Withney U-test, Fisher’s exact test, or χ², were used as appropriate. Abbreviations: COPD, Chronic obstructive pulmonary disease; BMI, Body mass index.

Table 3. Clinical characteristics of the study population.

	No COPD n = 626	Undiagnosed COPD n = 28	Diagnosed COPD n = 7	P-value
Spirometric parameters
FEV1 (l)	2.65 (2.21/3.30)	2.00 ± 0.65	1.14 ± 0.37	0.002
FEV1 z-score-GLI	−0.54 (−1.21/−0.15)	−2.22 ± 0.80	−3.70 ± 0.38	<0.001
FVC (l)	3.27 (2.70/4.06)	3.22 ± 0.88	2.47 ± 0.69	0.044
FVC z-score-GLI	−0.67 (−1.32/−0.00)	−1.12 ± 0.89	−2.44 ± 0.94	0.002
FEV1/FVC	0.81 (0.77/0.85)	0.63 (0.61/0.66)	0.44(0.34/0.55)	0.020
FEV1/FVC z-score-GLI	0.25 (−0.31/0.77)	−1.99 (−2.36/−1.65)	−3.82 (−4.14/−2.37)	0.010
Respiratory symptoms
Chronic cough, n (%)	175 (28.0)	10 (35.7)	4 (57.1)	0.401
Chronic phlegm, n (%)	169 (27.0)	14 (50)	5 (71.4)	0.415
Wheezing, n (%)	146 (23.3)	12 (42.9)	7 (100)	0.009
Dyspnea, n (%)	218 (34.8)	17 (60.7)	6 (85.7)	0.380
z-score classification of severity				<0.001
Mild (z-score≥ −2), n (%)	–	11 (39.3)	0 (0.0)
Moderate (−3 ≤ z-score< −2), n (%)	–	12 (42.9)	0 (0.0)
Severe (−4 ≤ z-score< −3), n (%)	–	5 (17.9)	6 (85.7)
Very severe (z-score< −4), n (%)	–	0 (0.0)	1 (14.3)
Reported diagnosis
Hypertension, n (%)	126 (20.1)	9 (32.1)	3 (42.9)	0.670
Diabetes, n (%)	68 (10.9)	4 (14.3)	0 (0.0)	0.562
Heart Disease, n (%)	34 (5.4)	2 (7.1)	1 (14.3)	0.499
Depression	18 (2.9)	22 (78.6)	4 (57.1)	0.340
Asthma, n (%)	48 (7.7)	3 (10.7)	5 (71.4)	0.003
COPD, n (%)	0 (0.0)	0 (0.0)	7 (100.0)	<0.001
Prior spirometry, n (%)
Ever	66 (10.5)	7 (25.0)	7 (100.0)	0.010
Last 12 months	16 (2.6)	1 (3.6)	3 (42.8)	0.019
Visit a physician during the last 12 months, n (%)	106 (16.9)	9 (32.1)	6 (85.7)	0.020
Pysical limitation, n (%)	139 (22.2)	21 (75.0)	7 (100.0)	0.146
Respiratory medication, n (%)	27 (4.3)	1 (3.5)	7 (100.0)	<0.001

P value represents comparison between undiagnosed and diagnosed subjects with COPD. Independent t-test, Mann Withney U-test, Fisher’s exact test, or χ², were used as appropriate. Abbreviations: COPD, Chronic obstructive pulmonary disease; GLI, Global Lung Initiative; FEV₁, Forced expiratory volume in the first second; FVC, Forced vital capacity.