Figures
- FIGURE 1
a) Total association between parental respiratory disease history and airway obstruction and respiratory symptoms. b) Indirect (path a and b) and direct (path c') associations between parental respiratory disease history and airway obstruction and respiratory symptoms through life-course factors.
Tables
- TABLE 1
Summary of COPD risk factors operationalised with respect to life period
COPD risk factor Critical life period and age of cohort members when data were collected Cumulative exposure Category Individual factor In utero/at birth Childhood Adulthood 0 years of age 7 years of age 11 years of age 16 years of age 23 years of age 33 years of age 42 years of age Smoking exposure Passive smoke exposure Smoking status during pregnancy (4 months) Living with a smoker Living with smoker at any stage Combined passive smoking exposure (in utero, childhood and adulthood) personal smoking in adulthood Personal smoking status Persistent smoker ever smoker, and never smoker SC SC (occupation and classified as: professional/managerial, unskilled nonmanual, skilled manual, unskilled manual) SC of male head SC of male head Own SC Combined social class at birth, 11 and 42 years (range 0–9), with higher scores indicating lower social class Asthma Asthma Report of ever having asthma or bronchitis Ever asthma in adulthood Childhood and adulthood reporting of asthma Others Low birth weight Birth weight <2.5 kg Preterm birth Gestation age <37 weeks Pneumonia Ever had pneumonia Occupation exposure Minimal or potential occupational exposure to dust, gases and fume Biomass exposure Paraffin or solid fuel as heating source SC: social class.
- TABLE 2
Descriptive statistics of life-course factors in the study sample
Cohort member characteristics Total (n=6212) No parental respiratory disease history (n=5983) Reported parental respiratory disease history (n=229) p-value# Smoking exposure Childhood passive smoke exposure 4185 (67%) 4015 (67%) 170 (74%) 0.024 Adulthood passive smoke exposure 3470 (56%) 3330 (56%) 140 (61%) 0.101 Adulthood smoking status 0.003 Never 3751 (60%) 3620 (61%) 131 (57%) Ever 1330 (21%) 1292 (22%) 38 (17%) Persistent 1131 (18%) 1071 (18%) 60 (26%) Cumulative smoking 0.002 0 (never) 905 (15%) 885 (15%) 20 (9%) 1 1874 (30%) 1802 (30%) 72 (31%) 2 1702 (27%) 1645 (28%) 57 (25%) 3 1031 (17%) 993 (17%) 38 (17%) 4 (persistent exposure) 700 (12%) 658 (11%) 42 (18%) SC At birth 0.001 SC1 1216 (20%) 1191 (20%) 25 (11%) SC2 619 (10%) 604 (10%) 15 (7%) SC3 3096 (50%) 2962 (50%) 134 (59%) SC4 1281 (21%) 1226 (20%) 55 (24%) At 11 years of age <0.001 SC1 1570 (25%) 1544 (26%) 26 (11%) SC2 670 (11%) 650 (11%) 20 (9%) SC3 2640 (43%) 2550 (43%) 90 (39%) SC4 1332 (22%) 1239 (21%) 93 (41%) At 42 years of age 0.001 SC1 2535 (41%) 2459 (41%) 76 (33%) SC2 1512 (24%) 1465 (25%) 47 (21%) SC3 1179 (19%) 1127 (19%) 52 (22%) SC4 986 (16%) 932 (16%) 54 (24%) Cumulative SC mean±sd (range 0–9) 4.42±2.43 4.38±2.42 5.41±2.29 <0.001 Asthma Childhood asthma 1391 (22%) 1328 (22%) 63 (28%) 0.058 Adulthood asthma 818 (13%) 766 (13%) 52 (23%) <0.001 Cumulative asthma 0.003 0 (never) 4430 (71%) 4290 (72%) 140 (61%) 1 1361 (22%) 1298 (22%) 63 (28%) 2 (persistent) 421 (7%) 395 (7%) 26 (11%) Others Low birth weight 317 (5%) 293 (5%) 24 (111%) <0.001 Born preterm¶ 216 (4%) 209 (4%) 7 (3%) 0.723 Had pneumonia¶ 266 (4%) 251 (4%) 15 (7%) 0.084 Biomass exposure¶ 776 (13%) 742 (12%) 34 (15%) 0.272 Occupational exposure 1897(31%) 1813 (30%) 84 (37%) 0.040 SC: social class (SC1: professional/managerial; SC2: unskilled nonmanual; SC3: skilled manual; SC4: unskilled manual). #: calculated by Chi-squared or independent sample t-test as appropriate, significant level set at p<0.1; ¶: based on mean of 10 imputed datasets.
- TABLE 3
Models detailing associations between parental respiratory disease history, individual life-course factors and symptomatic airflow obstruction (outcome), by category (smoking, social class, asthma and others)
Life-course factors Model 1a Model 1b Model 1c Model 1d Smoking Parental respiratory disease history 1.87 (1.21–2.89)* 1.71 (1.09–2.68)* 1.69 (1.08–2.64)* 1.70 (1.09–2.65)* Passive smoke childhood 1.46 (1.15–1.85)** 1.23 (0.97–1.58) Adulthood smoking Ever smoker 1.79 (1.34–2.38)*** 1.77 (1.33–2.36)*** Persistent smoker 4.93 (3.88–6.28)*** 4.81 (3.78–6.10)*** Cumulative smoke exposure 0 (never) 1.00 (ref.) 1 1.03 (0.67–1.59) 2 1.14 (0.74–1.76) 3 2.72 (1.80–4.10)*** 4 (persistent) 5.33 (3.55–8.00)*** Total indirect effects estimates (se) 0.027 (0.014) 0.104 (0.047)* 0.117 (0.048)* 0.123 (0.044)* Model 2a Model 2b Model 2c Model 2d SC Parental respiratory disease history 1.88 (1.21–2.92)* 1.82 (1.17–2.83)* 1.80 (1.16–2.79)* 1.76 (1.13–2.73)* At birth SC1 1.00 (ref.) SC2 1.15 (0.76–1.75) SC3 1.15 (0.86–1.54) SC4 1.30 (0.93–1.81) At 11 years of age SC1 1.00 (ref.) SC2 0.68 (0.43–1.08) SC3 1.13 (0.86–1.47) SC4 1.28 (0.95–1.73) At 42 years of age SC1 1.00 (ref.) SC2 1.34 (0.99–1.81) SC3 1.73 (1.30–2.31)*** SC4 1.94 (1.44–2.62)*** Cumulative SC 1.09 (1.04–1.14)*** Total indirect effects estimates (se) 0.020 (0.015) 0.051 (0.027) 0.063 (0.022)** 0.088 (0.028)*** Model 3a Model 3b Model 3c Model 3d Asthma Parental respiratory disease history 1.83 (1.18–2.83)* 1.54 (0.96–2.47) 1.53 (0.96–2.45) 1.62 (1.03–2.55)** Childhood asthma 2.17 (1.74–2.70)*** 1.30 (1.02–1.67)** Adulthood asthma 6.12 (4.89–7.64)*** 5.59 (4.39–7.11)*** Cumulative asthma 0 (never) 1.00 (ref.) 1 2.53 (1.98–3.24)*** 2 (persistent) 7.22 (5.44–9.59)*** Total indirect effects estimates (se) 0.041 (0.024) 0.180 (0.052)** 0.185 (0.053)*** 0.150 (0.048)** Model 4a Model 4b Model 4c Model 4d Others Parental respiratory disease history 1.88 (1.21–2.91)* 1.90 (1.22–2.94)** 1.87 (1.20–2.90)* 1.85 (1.19–2.87)* Low birth weight 1.34 (0.87–2.05) Pneumonia (childhood) 1.79 (1.16–2.77)* 1.78 (1.15–2.75)* Occupational exposure 1.39 (1.11–1.76)* 1.39 (1.10–1.75)* Total indirect effects estimates (se) 0.016 (0.014) 0.008 (0.010) 0.021 (0.014) 0.029 (0.017) Data are presented as OR (95% CI) unless otherwise stated. All models were adjusted for sex and recent chest infection (past 3 weeks prior to when spirometry was performed at age 45 years). SC: social class (SC1: professional/managerial; SC2: unskilled nonmanual; SC3: skilled manual; SC4: unskilled manual). *: p<0.05; **: p<0.005; ***: p<0.001.
- TABLE 4
Associations between parental respiratory disease history, combined life-course factors and symptomatic airflow obstruction (outcome)
Model 5a Model 5b Parental respiratory disease history 1.29 (0.80–2.09) 1.34 (0.84–2.14) Childhood passive smoke exposure 1.18 (0.91–1.52) Adulthood smoking Ever-smoker 1.71 (1.27–2.31)*** Persistent smoker 5.42 (4.19–7.01)*** SC at 42 years of age SC1 1.00 (ref) SC2 1.20 (0.87–1.67) SC3 1.29 (0.92–1.81) SC4 1.41 (1.00–1.99) Asthma Childhood 1.33 (1.02–1.72)* Adulthood 6.44 (5.01–8.27)*** Pneumonia (childhood) 1.33 (0.82–2.16) 1.13 (0.71–1.79) Occupational exposure 1.00 (0.76–1.30) 1.09 (0.84–1.40) Cumulative SC 1.03 (0.98–1.08) Cumulative smoking exposure 0 (never) 1.00 (ref.) 1 0.98 (0.63–1.52) 2 1.07 (0.68–1.67) 3 2.38 (1.55–3.64)*** 4 (persistent) 5.39 (3.51–8.27)*** Cumulative asthma 0 (never) 1.00 (ref.) 1 2.51 (1.95–3.23)*** 2 (persistent) 8.13 (5.98–11.07)*** Total effects estimate (se) 0.614 (0.258)** 0.603 (0.250)** Total indirect effects estimate (se) 0.359 (0.082)*** 0.308 (0.075)*** Model fit AIC 57 978.796 68 436.130 BIC 58 295.306 68 718.968 Data are presented as OR (95% CI) unless otherwise stated. All models were adjusted for sex and recent chest infection (past 3 weeks prior to when spirometry was performed at age 45 years). SC: social class (SC1: professional/managerial; SC2: unskilled nonmanual; SC3: skilled manual; SC4: unskilled manual); AIC: Akaike information criterion; BIC: Bayesian information criterion. *: p<0.05; **: p<0.005; ***: p<0.001.
Supplementary Material
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Supplementary material 00343-2019.SUPPLEMENT
