TABLE 2.
Description of the studies included
| Author and year | Type of study and country | Sample size | No. of never‐smokers (%)/no. of COPD never‐smokers (%) | No. of women (%) | COPD diagnosis | Risk factor analysed | Variable analysed | % increased risk of COPD/risk observed | Score |
|---|---|---|---|---|---|---|---|---|---|
| Orozco‐Levi et al, 20 2006 |
Case–control (hospital) Spain |
120 | 94 (78.3%)/42 (70%) | 120 (100%) | FEV1/FVC < 70% postBD | Biomass | Wood and charcoal | OR 4.5 (95%CI 1.4–14.2; p = 0.01) | 5 |
| Ekici et al, 21 2005 |
Case–control (population) Turkey |
596 | 596 (100%)/140 (100%) | 596 (100%) | FEV1/FVC < 70% preBD | Biomass |
No. of hours cooking × no. of years: ‐Group A: 68.8 h‐years ‐Group B: 68.8–152.4 h‐years ‐Group C: >152.4 h‐years |
23.1% (95% CI 13.4–33.2) ‐Group A: OR 1.7 (95%CI 1.0–3.1; p = 0.04) ‐Group B: OR 2.5 (95%CI 1.4–4.4; p = 0.001) ‐Group C: OR 3.3 (95%CI 1.9–5.7; p = 0.0001) |
5 |
| Regalado et al, 22 2006 |
Cross‐sectional Mexico |
841 | 841 (100%)/111 (100%) | 841 (100%) | FEV1/FVC < 70% preBD | Biomass | PM10 particulate concentration measured by nephelometer for 1 h while cooking |
OR FEV1/FVC < 70% + FEV1 < 80%: 3.9 (95%CI 0.94–16.3; p = 0.06) OR FEV1/FVC < 70%: 1.3 (95%CI 0.7–2.4; p = 0.32) FEV1 decrease 81 mL or 4.7% of that predicted with PM10 > 2.6 mg/m3 |
4 |
| Menezes et al, 19 2005 |
Cross‐sectional Brazil |
999 | 428 (42.9%) never‐smokers/not registered | 558 (55.8%) | FEV1/FVC < 70% postBD |
Occupation Biomass |
Occupation >10 years Exhibition charcoal stove for heating/cooking |
Occupation increases COPD risk 36% (p = 0.08) Coal stove exposure increases COPD risk 40% (p = 0.08) |
4 |
| Tuner et al, 32 2012 |
Cohorts USA |
811 961 | 375 087 (46.21%)/1797 deceased COPD never‐smokers | 449 361 (54.5%) | COPD medical diagnosis | Radon | Radon measurement >100 Bq/m3 | Mortality from COPD 1.03 (95%CI 0.86–1.25) | 6 |
| Lamprecht et al, 31 2011 |
Cross‐sectional China, Turkey, Austria, South Africa, Iceland, Germany, Poland, Norway, Canada, USA, Philippines, Australia, England, Sweden |
10 000 | 4291 (42.9%)/523 (12.2%) | 5231 (52.31%) | FEV1/FVC postBD <70% |
Respiratory infections in childhood Occupation Asthma |
Documented infections in childhood Occupation: Organic powder at least 10 years Asthma |
Infections in childhood: OR females 2.21 (95%CI 0.89–5.47 p = 0.087) and OR males 2.82 (95%CI 0.94–8.51; p = 0.065) Occupation: OR females 1.96 (95%CI 1.2–3.2; p = 0.007), OR males 2.18 (95%CI 0.99–4.8; p = 0.054) Asthma: OR females 4.62 (95%CI 3.04–7.02; p < 0.001) and OR males 4.12 (95%CI 2.06–8.26; p < 0.001) |
7 |
| Perez‐Padilla et al, 29 2012 |
Cross‐sectional Latin America: Chile, Uruguay, Brazil, Venezuela, Mexico |
5315 | 2278 (42.3%)/240 (10.5%) | 3211 (60.41%) | FEV1/FVC < 70% postBD |
Tuberculosis (TBC) Asthma |
Previous diagnosis of tuberculosis or asthma |
TBC: OR 3.66 (95%CI 1.4–9.55; p = 0.01) Asthma: OR 4.24 (95%CI 2.47–7.28; p < 0.001) |
6 |
| Lee et al, 30 2015 |
Cross‐sectional Korea |
5784 | 3473 (57.7%)/258 (31.7%) | 3053 (52.78%) | FEV1/FVC < 70% preBD |
Occupation Tuberculosis |
Occupation: manual labour: construction, mining Previous diagnosis of tuberculosis |
7.6% Occupation: OR 2.6 (95%CI 1.3–5.3; p = 0.007) TBC: OR 4.5 (95%CI 2.3–8.7; p < 0.0001) |
5 |
| Yin et al, 24 2007 |
Cohorts China |
6497 | 6497 (100%)/342 | 5957 (89.6%) | FEV1/FVC < 70% preBD | Passive smoking (home and workplace) | Density and duration (40 h/weeks for >5 years) |
OR home: 1.60 (95%CI 1.23–2.10) OR workplace: 1.50 (95%CI 1.14–1.97; p = 0.002) OR home + workplace: 1.48 (95%CI 1.18–1.85 p = 0.001) |
8 |
| Zhou et al, 25 2009 |
Cross‐sectional China |
20 245 | 12 471 (66.6%)/644 (38.6%) | 10 236 (88.7%) | FEV1/FC < 70% postBD |
Biomass Passive smoking |
Exposure to biomass if used for cooking/heating more than 1 hour Passive smoking: exposure to tobacco at home/workplace |
Biomass cooking: OR 1.31 (95%CI 1.08–1.58; p = 0.006) Biomass heating: OR 1.48 (95%CI 1.07–2.05; p = 0.017) Passive smoking: OR 1.31 (95%CI 1.06–1.61; p = 0.014) |
8 |
| Jordan, 26 2011 |
Cross‐sectional England |
21 104 | 8859 (42%)/not registered | 11 257 (53.3%) | FEV1/FVC < 70% preBD | Passive smoking | Exposure in hours/weeks | OR 1.98 (95%CI 1.03–3.79) if exposure greater than 20 h/week | 5 |
| Hagstad et al, 27 2014 |
Cross‐sectional Sweden |
2118 | 2118 (100%)/140 (6.65%) | 1251 (59.1%) | FEV1/FVC < 70% preBD | Passive smoking | Questionnaire on exposure to tobacco at home and in the workplace |
OR previous home: 2.03 (95%CI 1.23–3.34; p = 0.005) OR all homes: 1.98 (95%CI 1.23–3.18; p = 0.005) OR previous workplace: 2.06 (95%CI 1.30–3.27; p = 0.002) OR all homes and workplaces 3.94 (95%CI 1.41–11; p = 0.009) |
5 |
| Hnizdo, 13 2002 |
Cross‐sectional USA |
9823 | 4369 (44.47%)/106 (15.29%) | 5166 (52.59%) |
FEV1/FVC < 70% preBD+FEV1 < 80% |
Occupation | Occupation: industry and time | COPD fraction attributed to occupation in non‐smokers 31.1% | 5 |
| Blanc et al, 14 2009 |
Cohorts USA |
1504 | 323 (21.47%)/165 (13%) | 876 (58.29%) | FEV1/FVC < 70% preBD | Occupation | Exposure to VGDF and JEM | OR 2 (95%CI 1.28–3.18) | 7 |
| Mehta et al, 15 2012 |
Cohorts Switzerland |
4267 | 1940 (45%)/253 (43.84%) | 2121 (49.7%) | FEV1/FVC < 70% preBD | Occupation |
Biological powder Mineral powder Gases/vapours VGDF |
IRR biological powder: 3.14 (95%CI 0.88–11.24) IRR mineral powder: 3.22 (95%CI 0.84–12.36) IRR gases/vapours: 3.94 (95%CI 1.23–12.58) IRR VGDF: 3.28 (95%CI 1.03–10.41) |
7 |
| Mahmood et al, 23 2017 |
Cross‐sectional India |
200 | 113 (56.5%)/113 (56.5%) | Not registered | FEV1/FVC < 70% postBD |
Biomass Tuberculosis Asthma |
Questionnaire |
Biomass: 53.98%, p = 0.0001 Tuberculosis: 32.74%, p = 0.0001 Asthma: 14.16%; p = 0.003 |
3 |
| Hagstad et al, 16 2015 |
Cross‐sectional Sweden |
1839 | 967 (52.6%)/74 (7.7%) | 870 (47.3%) | FEV1/FVC < 70% postBD | Occupation | Exposure to gas, dust or vapours | OR 1.85 (95%CI 1.03–3‐33) | 5 |
| Tan et al, 28 2015 |
Cross‐sectional Canada |
4893 | 2295 (47%)/147 (6.43%) | 2797 (57.16%) | FEV1/FVC < 70% postBD |
Asthma Childhood infections Passive smoking |
Record of asthma or history of hospitalisation in childhood Passive smoking: partner of a smoker in the preceding 2 weeks |
Asthma: OR 2.23 (1.36–3.66) for mild COPD, OR 4.94 (2.94–8.30) moderate–severe COPD Childhood infections: OR 4.80 (95%CI 2.43–9.46) for COPD moderate–severe Passive smoking: OR 2.60 (1.05–6.43) for mild COPD women |
6 |
| Ramadan, 17 2012 |
Cross‐sectional Egypt |
300 | 120 (40%)/120 (40%) | 70 (23.34%) | FEV1/FVC < 70% postBD |
Occupation Biomass |
Occupation: risk occupation more than 3 months Biomass: cooking exposure/heating for at least 6 months |
Occupation: OR 1.09 (95%CI 0.41–0.78; p < 0.05) Biomass: OR 1.26 (95%CI 0.38–0.82; p < 0.05) |
5 |
| Denguezli et al, 18 2016 | Cross‐sectional. Tunisia | 661 | 485 (73.4%)/28 (4.7%) | 352 (67.2%) | FEV1/FVC < 70% postBD |
Occupation Biomass Asthma Childhood hospitalisation |
Occupation: risk occupation at least 3 months Biomass: exposure at least 6 months Asthma diagnosis Childhood hospitalisation record |
Occupation >10 years: OR 1.87 (95%CI 1140–12.863; p = 0.015) Biomass ≥ 10 years kitchen: OR 1.479 (95%CI 0.3–5.855; p = 0.578) Asthma: OR 10.621 (95%CI 2.897–38.937; p < 0.01) Childhood hospitalisation: OR 3.075 (95%CI 0.35–27.017; p = 0.311) |
4 |
Abbreviations: JEM, job‐exposure matrices; postBD, post‐bronchodilator; preBD, pre‐bronchodilator; TBC, tuberculosis; VGDF, occupational exposure to vapours, gases, dust or fumes.