Baseline information on individual studies assessing biomarkers levels in chronic obstructive pulmonary disease(COPD) patients
| First author [ref.] | Participants n | Plasma/serum biomarkers | Main findings |
| Takabatake [38] | 35 patients 22 controls | IFN-γ sIL-2R Neopterin sICAM-1 | Impaired systemic cell-mediated immunity is present in COPD patients and is associated with an increased susceptibility to acute respiratory tract infections. Neopterin levels are increased in stable COPD patients in comparison to the control subjects. |
| Phua [53] | 43 patients# 62 controls | sTREM-1 | Serum levels of the sTREM-1 are significantly higher in COPD patients than in the control group. Anthonisen type 1 exacerbations had higher levels than types 2 and 3 and might also have a higher airway bacterial load. |
| Hurst [36] | 90 patients | 36 analytes | Levels of CRP, IL-6 and sICAM-1 levels are increased during exacerbations in comparison to the stable state. CRP concentration and the presence of a major exacerbation symptom are useful in confirming COPD exacerbation. Systemic biomarkers were not useful for predicting severity. |
| Pinto-Plata [71] | 88 patients | CRP | CRP may be a systemic marker of the underlying inflammatory process seen in stable COPD. CRP levels are raised independently of tobacco consumption, and reduced in patients using inhaled corticosteroids. |
| Man [69] | 4803 patients | CRP | For patients with mild-to-moderate COPD, CRP may accurately detect patients at high risk mortality. |
| Weis [50] | 166 patients | CRP | CRP values are in the normal range in ∼50% of patients admitted with COPD exacerbation. Patients with increased sputum purulence had higher CRP levels. CRP may be used as a marker of significant bacterial infection in exacerbation episodes. |
| de Torres [68] | 130 patients | CRP | CRP levels in stable COPD patients are strongly associated with arterial oxygen tension and 6-min walk distance. Levels correlated independently with FEV1, GOLD stage and BODE index. |
| Muller [26] | 60 patients# 50 controls | Pro-ANP | Levels of pro-ANP were higher in the group of patients with exacerbation in comparison to the control group. There was no difference in pro-ANP levels according to the Anthonisen criteria and the severity of COPD. |
| Hurst [34] | 41 patients | IL-6 CRP | The systemic inflammatory response observed during an exacerbation is proportional to the inflammation present in the lower airways, and is greater in the presence of a bacterial pathogen in the sputum. |
| Pinto-Plata [64] | 48 patients 48 controls | 143 analytes | Some of the biomarkers analysed are associated with clinical variables, such as degree of airflow limitation, lung transfer factor, BODE index and exacerbation frequency. |
| Dahl [67] | 1302 patients | CRP | CRP levels in the stable state are a strong long-term predictor of future outcomes in COPD patients, independent of smoking and lung function. |
| Stolz [47] | 208 patients | PCT | PCT guidance for acute exacerbations offers an advantage over standard therapy in reducing antibiotic use without negative consequences for patient recovery. |
| Stolz [51] | 167 patients | Copeptin CRP PCT | Copeptin might be a better prognostic factor than CRP and PCT for short- and long-term prognosis in patients undergoing exacerbations requiring hospitalisation. |
| Radsak [39] | 12 patients 10 controls | sTREM-1 | Serum concentrations of sTREM-1 are increased in patients with COPD, compared with levels in the control group. Levels of sTREM-1 during the stable state showed a significant negative correlation with lung function impairment. |
| Muller [25] | 60 patients# 50 controls | Copeptin | Levels of copeptin were higher in the group of patients with exacerbation in comparison to the control group. There was no difference in copeptin levels according to the Anthonisen criteria and the severity of COPD. |
| Perera [37] | 73 patients | IL-6 CRP | Non-recovery of symptoms at exacerbation is associated with persistently increased systemic inflammation. The time course of systemic inflammation following the exacerbation episode is different between frequent and infrequent exacerbators. |
| Pinto-Plata [35] | 20 patients | IL-6 IL-8 LTB4 TNF-α SLPI | Patients admitted to the hospital because of an exacerbation experience significant changes in systemic cytokine levels that correlate with symptoms and lung function. During the episode there is a worsening of the airflow obstruction and an increased systemic demand. |
| Prat [27] | 135 patients# | Pro-ANP | Levels of pro-ANP are increased in COPD patients with pneumonia, and its levels correlate with PSI. |
| Bircan [52] | 113 patients 30 controls | CRP | A high level of serum CRP may indicate infectious exacerbation origin in COPD patients and correlates with sputum purulence and increased serum WBC counts. |
| de Torres [70] | 218 patients | CRP | For patients with moderate-to-very severe COPD, CRP levels measured during clinical stability are not associated with survival and do not add information to the risk assessment provided by the BODE index. |
| Stolz [65] | 208 patients | BNP | BNP levels predicted independently the need for intensive care, but failed to adequately predict short- and long-term prognosis in patients admitted with acute exacerbation. |
| Stolz [66] | 167 patients | Pro-ADM Pro-ET1 | Levels of pro-ADM, but not pro-ET1, on admission because of an acute exacerbation, independently predicted 2-yr survival, suggesting it could be useful for predicting prognosis. |
IFN: interferon; sIL-2R: soluble interleukin-2 receptor; sICAM: soluble intercellular adhesion molecule; sTREM: soluble triggering receptor expressed on myeloid cells; CRP: C-reactive protein; IL: interleukin; FEV1: forced expiratory volume in 1 s; GOLD: Global Initiative for Chronic Obstructive Lung Disease; BODE: body mass index, airway obstruction, dyspnoea and exercise capacity; pro-ANP: pro-atrial natriuretic peptide; PCT: procalcitonin; LTB4: leukotriene B4; TNF: tumour necrosis factor; SLPI: secretory leukocyte protease inhibitor; PSI: pneumonia severity index; WBC: white blood cells; BNP: brain natriuretic peptide; pro-ADM: pro-adrenomedullin; pro-ET1: pro-endothelin-1. #: the total population included a subgroup of COPD patients.