Table 1.
Characteristics of included studies.
| Author, Year of publication | Country | Study centers and design** | Population (recruitment period and inclusion criteria) | Timing of sample collection | Reference standard (microbiological culture obtained from) | Index tests (cut-off value) | Sample size (bacterial %) | |
|---|---|---|---|---|---|---|---|---|
| Tanriverdi et al. (17) | Turkey | Single centerProspective cohort | Jan 01–Mar 31 2014 | Hospitalized AECOPD patients | On-admission | Tracheal aspirate or sputum |
CRP (91.5 mg/l) PCT (0.4 ng/ml) N/L ratio (11.5) |
77 (36) |
| Dev et al. (18) | United Kingdom | Prospective cohort | Not reported | Hospitalized AECOPD patients | On-admission | Sputum | CRP (10 mg/l) | 50 (58) |
| Peng et al. (19) | China | Single centerProspective cohort | Not reported | Hospitalized AECOPD patients | On-admission | Sputum | CRP (19.65 mg/l) | 81 (68) |
| Clark et al. (20) | United Kingdom | Single centerRetrospective analysis | Between Sept 2005 and May 2008 | Hospitalized AECOPD* patients | On-admission | Blood, sputum, urine and nasopharyngeal swab |
CRP (10 mg/l) | 264 (25) |
| Xiong et al. (21) | China | Single centerProspective cohort | Jan 2014–Jan 2016 | Hospitalized AECOPD patients | On-admission | Sputum | CRP (31.68 mg/l) PCT (0.76 ng/ml) SAA (31.28 mg/l) |
78 (49) |
| Sethi et al. (15) | USA | Single centerProspective cohort | Jan 01 1999–Dec 31 2000 | COPD outpatients, followed monthly and at exacerbations | At each clinic visit, at exacerbation |
Sputum | CRP (2.37 mg/l) Sputum NE (0.76 nM) Sputum IL-8 (1.39 ng/ml) Sputum TNFa (320 pg/ml) |
150 exacerbations from 46 patients (26) |
| Bathoorn et al. (22) | Netherlands | Single center prospective cohort | Not reported | COPD outpatients experiencing an exacerbation | At each clinic visit, at exacerbation |
Sputum | CRP (2 mg/l) Sputum TNFa (30 pg/ml) Sputum MPO (12 ug/ml) |
37(22) |
| Numbere et al. (23) | United Kingdom | Single center retrospective analysis (congress abstract) | Not reported | Hospitalized AECOPD* patients | Within 24 h of admission | Sputum | CRP (50 mg/l) | 122 (55) |
| Bafadhel et al. (24) | United Kingdom | Single centerProspective cohort | Not reported | COPD outpatients with >1 exacerbations in the preceding 12 months | At each visit | Sputum | CRP (10 mg/l) Sputum IL-1b (125 pg/ml) |
148 exacerbations (75 patients) (53) |
| Nseir et al. (25) | France | Single centerProspective cohort | Dec 2004–June 2006 | Hospitalized AECOPD patients, requiring mechanical ventilation | ICU admission, before AB therapy |
Endotracheal aspirate | PCT (0.5 ng/ml) | 98 (41) |
| Ergan et al. (26) | Turkey | Single centerProspective cohort | May 01 2007- July 31 2009 | Hospitalized AECOPD patients, requiring ICU admission | ICU admission | Sputum or endotracheal aspirate or bronchoalveolar | PCT (0.25 ng/ml) | 52 (31) |
| Falsey et al. (9) | USA | Single centerprospective cohort | Between Nov 01 and May 30 2008–2009 and 2009–2010 | Hospitalized AECOPD patients | At enrollment | Blood culture, sputum Gram stain and culture, nose and throat swabs |
PCT (0.25 ng/ml) | 184 (17) |
| Chang et al. (27) | Taiwan | Single centerProspective cohort | Aug 2009–Aug 2010 | COPD patients who visited ED with acute exacerbation | At Emergency Department visit | Sputum | PCT (0.5 ng/ml) | 72 (42) |
| Chang et al. (28) | China | Single centerProspective cohort | Not reported | AECOPD* outpatients | At presentation of exacerbation | Sputum | PCT (0,155 ng/ml) | 45 (33) |
| Daubin et al. (29) | France | Single centerProspective cohort | Sept 2005–Sept 2006 | Hospitalized AECOPD patients | At ICU admission | Sputum or tracheal aspirate |
PCT (0,1 ng/ml) | 35 (14) |
| Choi et al. (30) | Korea | Single centerRetrospective analysis | Jan 2011–May 2017 | Hospitalized AECOPD patients | On-admission | Blood, sputum, and urine | Eosinophil (2%) | 736 (42) |
| Qian et al. (31) | China | Single centerRandomized controlled trial | Jan–Dec 2014 | Hospitalized AECOPD patients | On-admission | Sputum | CD64 index (2,5) | 150 (55) |
| Soler et al. (32) | Spain | Single centerRandomized controlled trial | Jan 2007–May 200 | Hospitalized AECOPD patients | At enrollment | Sputum | Sputum color (purulent) |
41 (34) |
| Burley et al. (33) | United Kingdom | Multicenter prospective cohort | Nov 1999–Feb 2003 | Adult patients with AECOPD | At enrollment | Sputum | Sputum color (purulent) |
97 (60) |
| Stockley et al. (34) | United Kingdom | Single centerProspective cohort | Not reported | AECOPD outpatients | On-admission | Sputum | Sputum color (purulent) |
121 (71) |
| Dal Negro et al. (35) | Italy | Single centerProspective cohort | Not reported | Hospitalized AECOPD patients | On-admission | Sputum | Sputum TNFa+IL-8+IL-1b (492 pg/ml, 4,811 ng/ml, 2,818 pg/ml) |
124 (39) |
These studies did not identify COPD according to the GOLD (3) criteria, and AECOPD according to Anthonisen criteria (5) (Populations in studies not marked with * were defined by GOLD criteria and Anthonisen criteria). One article (15) defined AECOPD according to the guidelines of the American Thoracic Society (36). The differences in these definitions can be considered negligible in clinical practice. The included abstracts (22, 27) did not provide information on by which definition AECOPD was defined.
Study designs are shown according to full text articles, however in this network meta-analysis we interpreted only admission findings, therefore we considered the studies as cross sectional studies.
AECOPD, acute exacerbation of chronic obstructive pulmonary disease; CRP, C-reactive protein; ED, Emergency Department; ICU, intensive care unit; IL-1b, interleukin one beta; IL-8, interleukin eight; MPO, myeloperoxidase; NE, neutrophil elastase; N/L, neutrophil-lymphocyte ratio; PCT, procalcitonin; SAA, serum amyloid A; TNFa, tumor necrosis factor alfa.