Table 3.
Characteristics of the included studies.
| Study | Year | Country | Sample size | Mean age | Sex(male/Female) | Smoking status |
Reversibility test |
Treat with | COPD status |
NOS | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Case | Control | Case | Control | Steroids | ||||||||
| Calikoglu9 | 2004 | Turkey | 41 | 62.18 ± 2.50 | 54.73 ± 2.23 | NR | NR | NR | No | NR | Exacerbated | 6 |
| Agusti10 | 2012 | Spain | 2409 | 63.5 ± 7.1 | 53.0 ± 8.6 | 1160/1004 | 76/169 | NR | Yes | NR | NR | 6 |
| Once11 | 2010 | Turkey | 73 | 62.8 ± 5.5 | 61.8 ± 7.4 | 38/2 | 31/2 | Ex-smokers | No | No | NR | 7 |
| Kleniewska12 | 2016 | Poland | 42 | 59.8 ± 6.7 | 43.7 ± 14.4 | 20/0 | 15/7 | NR | Yes | No | Stable | 6 |
| Rovina13 | 2007 | Greece | 30 | 54 ± 9 | 46 ± 11 | NR | NR | Current-smokers | Yes | No | NR | 8 |
| Gagnon14 | 2014 | Canada | 56 | 65 ± 6 | 62 ± 8 | 25/12 | 13/6 | Ex-smokers | No | NR | Mild | 8 |
| Ben Anes15 | 2017 | Tunisia | 285 | 61.58 ± 1.75 | 58.15 ± 0.7 | 50/6 | 203/26 | Ex-smokers | Yes | NR | Exacerbated | 8 |
| Perez-deLiano16 | 2017 | Spain | 109 | 65.6 ± 10.1 | 59.8 ± 10.5 | 18/26 | 53/12 | NR | Yes | NR | NR | 5 |
| FoschinoBarbaro17 | 2007 | UK | 42 | NR | NR | 24/3 | 12/3 | Ex-smokers | Yes | No | Stable | 8 |
| Barreiro18 | 2013 | Spain | 21 | 59 ± 8 | 58 ± 14 | 9 | 12 | Ex-smokers | No | No | NR | 8 |
| Beeh19 | 2003 | Germany | 26 | 59 ± 9.25 | 31 ± 8.75 | 8/4 | 8/6 | Ex-smokers | Yes | No | Stable | 7 |
| Di Stefano20 | 2018 | Italy | 41 | NR | NR | 19/4 | 8/10 | Ex-smokers | Yes | No | Exacerbated | 5 |
| Breyer21 | 2011 | Netherlands | 127 | NR | NR | NR | NR | Ex-smokers | No | No | Exacerbated | 4 |
| Zhang22 | 2016 | China | 89 | 61.14 ± 10.21 | 60.92 ± 9.62 | 30/20 | 23/16 | NR | Yes | No | Moderate | 8 |
| Dima23 | 2010 | Greece | 38 | 58.4 ± 2.0 | 41.5 ± 3.5 | NR | NR | Ex-smokers | Yes | No | NR | 4 |
| Kawayama24 | 2016 | UK | 20 | 62.2 ± 6.6 | 64.2 ± 6.6 | 7/3 | 5/5 | Ex-smokers | No | Inhaled | NR | 6 |
| Gaki25 | 2011 | Greece | 354 | 63 ± 1.86 | 60 ± 1.71 | 169/53 | 97/35 | Ex-smokers | No | Inhaled | Stable | 9 |
| Godoy26 | 2003 | Brazi | 24 | 62 ± 2.25 | 54 ± 1.5 | 14/0 | 5/5 | NR | No | No | NR | 5 |
| Hacievliyagil27 | 2012 | Turkey | 40 | 61.2 ± 1.7 | 59.1 ± 5.4 | 17/3 | 14/6 | NR | Yes | Oral | Stable | 6 |
| Huertas28 | 2010 | Italy | 33 | 69 ± 8 | 63 ± 7 | NR | NR | NR | No | No | Stable | 6 |
| Ju29 | 2011 | China | 130 | 65.17 ± 6.79 | 63.98 ± 5.77 | 54/16 | 21/39 | Ex-smokers | Yes | No | Stable | 9 |
| Karadag30 | 2007 | Turkey | 125 | 63.5 ± 7.59 | 61.10 ± 7.68 | NR | NR | NR | Yes | Inhaled | Stable | 7 |
| Karadag31 | 2008 | Turkey | 65 | 65.6 ± 7.8 | 63.2 ± 7.6 | NR | NR | Ex-smokers | Yes | No | Stable | 7 |
| Shin32 | 2007 | Korea | 105 | 63.6 ± 7.4 | 66.5 ± 8.9 | NR | NR | NR | No | No | Stable | 6 |
| Kythreotis33 | 2008 | Greece | 77 | 65.8 ± 8.3 | 65.9 ± 9.6 | 43/9 | 19/6 | Ex-smokers | No | No | Exacerbation | 9 |
| Liu34 | 2009 | China | 63 | 70 ± 7 | 70 ± 7 | NR | NR | No-smoker | No | No | Stable | 7 |
| Huang35 | 2016 | China | 67 | 60.2 ± 10.1 | 55.7 ± 10.3 | 21/11 | 19/16 | NR | Yes | NR | NR | 7 |
| Moermans36 | 2011 | Belgium | 128 | 62 ± 12 | 40 ± 12 | 73/21 | 24/10 | Ex-smokers | Yes | Yes | Stable | 9 |
| Piehl-Aulin37 | 2008 | Sweden | 40 | 64 ± 8.7 | 61.9 ± 7.9 | 11/15 | 7/7 | Ex-smokers | No | Stable | 9 | |
| Tan38 | 2016 | China | 20 | 65 ± 3 | 50 ± 5 | 6/4 | 4/6 | Ex-smokers | Yes | Yes | Stable | 7 |
| Guiot39 | 2017 | Belgium | 62 | 63 ± 9 | 55 ± 9 | 24/8 | 11/19 | NR | No | NR | NR | 5 |
| Sarioglu40 | 2015 | Turkey | 175 | 64.0 ± 8.9 | 61.5 ± 9.2 | 100/10 | 55/10 | Ex-smokers | Yes | No | Stable | 9 |
| Uzum 41 | 2013 | Turkey | 49 | 65.9 ± 10.0 | 50.2 ± 8.4 | NR | NR | No-smoker | No | No | Stable | 7 |
| Kosacka42 | 2015 | Poland | 210 | 62.2 ± 9.37 | 49.48 ± 13.68 | 121/60 | 18/11 | Ex-smokers | No | NR | Stable | 9 |
| Cheng43 | 2008 | China | 343 | 71.9 ± 8.0 | 74.7 ± 3.7 | 152/32 | 129/30 | Ex-smokers | Yes | NR | NR | 6 |
| Valipour44 | 2008 | Austria | 60 | 62 ± 9 | 59 ± 8 | 23/7 | 23/7 | NR | Yes | No | Exacerbation | 8 |
| Zhang45 | 2010 | China | 65 | 70.93 ± 5.58 | 69.16 ± 7.43 | 38/8 | 13/6 | Ex-smokers | Yes | No | Stable | 9 |
| Soler46 | 1999 | Spain | 21 | 68 ± 9 | 51 ± 11 | 13/0 | 5/3 | Ex-smokers | No | No | Stable | 7 |
| Vera47 | 1996 | UK | 30 | 62.5 ± 3.2 | 39.4 ± 3.1 | NR | NR | Ex-smokers | No | No | NR | 6 |
| De Godoy48 | 1996 | US | 23 | 67.0 ± 4.9 | 63.5 ± 5.8 | 6/4 | 11/2 | NR | No | No | NR | 6 |
COPD, chronic obstructive pulmonary disease; NOS, Newcastle-Ottawa Quality Assessment Scale; NR, not recorded