Sex Differences in the International Primary Care Airways Group Questionnaire for Screening of Chronic Obstructive Pulmonary Disease: A Retrospective, Cross-Sectional Study

Figures & data

Table 1 Characteristics of Study Participants

	Total (n = 4364)	Men (n = 2784)	Women (n = 1580)	P-value
Age, years	53 (46–60)	54 (47–61)	51 (46–60)	<0.001*
Current or ex-smoker	2906 (66.6)	2370 (85.1)	536 (33.9)	<0.001*
Smoking history, pack-years	27.1 ± 22.1	29.9 ± 22.7	14.6 ± 13.8	<0.001*
BMI, kg/m^2	24.0 ± 3.4	24.5 ± 3.2	23.1 ± 3.5	<0.001*
FVC, L	3.2 ± 0.8	3.6 ± 0.8	2.6 ± 0.6	<0.001*
FEV1, L	2.6 ± 0.7	2.9 ± 0.7	2.1 ± 0.5	<0.001*
%FEV1, %	90.9 ± 16.3	87.6 ± 15.4	96.8 ± 16.1	<0.001*
FEV1/FVC, %	81.8 ± 8.4	80.8 ± 8.8	83.6 ± 7.4	<0.001*
FEV1/FVC < 70	285 (6.5)	225 (8.1)	60 (3.8)	<0.001*
Total score of IPAG questionnaire	16.5 ± 5.6	17.5 ± 5.7	14.8 ± 4.7	<0.001*
COPD Stage
I/II/III/IV	79/157/44/5	61/121/38/5	18/36/6/0	0.353

Notes: *P<0.05. Values are presented as medians (interquartile ranges), numbers (percentages), or means ± standard deviations.

Abbreviations: BMI, body mass index; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 s; %FEV₁, percentage of predicted FEV₁; IPAG, International Primary Airways Group; COPD, chronic obstructive pulmonary disease.

Figure 1 Flowchart of the study participants.

Note: Overall, 4427 participants were included in this study, of which 2784 were men and 1580 were women.

Abbreviation: IPAG, International Primary Airways Group.

Table 2 Prevalence of Airflow Limitation and Odds Ratios for Male Participants

Question	Total Number (n = 2784)	Number with AL (n = 225)	Odds Ratio	95% CI	P-value
1. Age, years
40–49	914 (32.8)	22 (2.4)	Reference
50–59	940 (33.8)	54 (5.7)	2.25	1.35–3.75	0.002*
60–69	546 (19.6)	55 (10.1)	3.94	2.35–6.61	<0.001*
70+	384 (13.8)	94 (24.5)	10.61	6.46–17.44	<0.001*
2. Smoking history, pack-years
0–14	979 (35.2)	47 (4.8)	Reference
15–24	530 (19.0)	30 (5.7)	1.38	0.84–2.28	0.206
25–49	904 (32.5)	93 (10.3)	2.15	1.46–3.16	<0.001*
50+	371 (13.3)	55 (14.8)	2.40	1.54–3.73	<0.001*
3. BMI, kg/m^2
< 25.4	1786 (64.2)	148 (8.3)	2.20	0.93–5.20	0.072
25.4–29.7	832 (29.9)	71 (8.5)	2.13	0.89–5.12	0.091
> 29.7	166 (6.0)	5 (3.6)	Reference
4. Weather affects cough
Yes	952 (34.2)	86 (9.0)	1.15	0.85–1.56	0.362
No or no cough	1832 (65.8)	139 (7.6)	Reference
5. Phlegm without a cold
Yes	880 (31.6)	89 (10.1)	1.05	0.74–1.50	0.776
No	1904 (68.4)	136 (7.1)	Reference
6. Phlegm in the morning
Yes	551 (18.4)	51 (10.0)	Reference
No	2273 (81.6)	174 (7.7)	1.14	0.76–1.71	0.533
7. Wheeze frequency (any)
Never	2494 (89.6)	160 (6.4)	Reference
Sometimes or often	290 (10.4)	65 (22.4)	3.50	2.44–5.03	<0.001*
8. Have or had any allergies
Yes	445 (16.0)	33 (7.4)	Reference
No	2339 (84.0)	192 (8.2)	1.08	0.71–1.65	0.714

Notes: *P<0.05. Values are numbers (percentages) of participants.

Abbreviation: AL, airflow limitation.

Table 3 Prevalence of Airflow Limitation and Odds Ratios for Female Participants

Question	Total Number (n=1580)	Number with AL (n = 60)	Odds Ratio	95% CI	P-value
1. Age, years
40–49	567 (35.9)	15 (2.6)	Reference
50–59	554 (35.1)	17 (3.1)	1.14	0.56–2.34	0.718
60–69	276 (17.5)	8 (2.9)	1.04	0.41–2.58	0.942
70+	183 (11.6)	20 (10.9)	4.30	2.04–9.04	<0.001*
2. Smoking history, pack-years
0–14	1352 (85.6)	47 (3.5)	Reference
15–24	129 (8.2)	8 (6.2)	1.76	0.77–4.04	0.18
25–49	83 (5.3)	2 (2.4)	0.60	0.14–2.61	0.496
50+	16 (1.0)	3 (18.8)	5.69	1.42–22.69	0.014*
3. BMI, kg/m^2
<25.4	1217 (77.0)	48 (3.9)	3.70	0.49–27.96	0.205
25.4–29.7	290 (18.4)	11 (3.8)	2.45	0.30–19.97	0.402
> 29.7	73 (4.6)	1 (1.4)	Reference
4. Weather affects cough
Yes	242 (15.3)	13 (5.4)	1.49	0.76–2.96	0.248
No or no cough	1338 (84.7)	47 (3.5)	reference
5. Phlegm without a cold
Yes	338 (21.4)	19 (5.6)	1.38	0.71–2.68	0.341
No	1242 (78.6)	41 (3.3)	Reference
6. Phlegm in the morning
Yes	167 (10.6)	10 (6.0)	Reference
No	1413 (89.4)	50 (3.5)	0.79	0.34–1.84	0.586
7. Wheeze frequency (any)
Never	1433 (90.7)	48 (3.3)	Reference
Sometimes or often	147 (9.3)	12 (8.2)	2.32	1.11–4.88	0.026*
8. Have or had any allergies
Yes	384 (24.3)	9 (2.3)	Reference
No	1196 (75.7)	51 (4.3)	2.10	0.96–4.59	0.065

Notes: *P<0.05. Values are numbers (percentages) of participants.

Abbreviation: AL, airflow limitation.

Table 4 The Sensitivity and Specificity of Different Cut-off Scores for Identifying Participants with Airflow Limitation

Cut-Off	Men		Women
	Sensitivity (%)	Specificity (%)	Sensitivity (%)	Specificity (%)
14	90.7	27.2	80.0	38.0
15	87.1	35.9	76.7	43.9
16	84.9	42.2	58.3	61.8
17	83.6	47.1	56.7	65.9
18	80.0	53.7	56.7	70.5
19	72.0	63.4	50.0	77.1
20	68.9	67.6	41.7	86.1
21	66.2	71.3	35.0	87.4

Notes: The cut-off values are for scores in the International Primary Airways Group questionnaire, out of a possible 38. Participants above the cut-off value are deemed to have airway limitation.

Figure 2 Receiver operating characteristic (ROC) curves for International Primary Airways Group questionnaire scores by sex (men:

, women:

). The area under the ROC curve was 0.741 for men and 0.670 for women.