Assessment of some inflammatory biomarkers as predictors of outcome of acute respiratory failure on top of chronic obstructive pulmonary disease and evaluation of the role of bacteria

The Significance of Serum Interleukin-8 in Acute Exacerbations of Chronic Obstructive Pulmonary Disease

BACKGROUNDS

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is closely related to disease mortality. Systemic inflammation is considered to be involved in the pathogenesis of AECOPD. The current study aimed to investigate the clinical significance of the classic chemokine interleukin (IL)-8 in serum during AECOPD.

MATERIALS AND METHODS

In this current cross sectional, observational study, 50 patients with AECOPD, 25 patients with stable COPD and 25 healthy nonsmokers as the control group were selected. Clinical characteristics and spirometry data were collected. All patients were classified as grade 1-4 based on forced expiratory volume in 1 second (FEV1) after bronchodilation according to the GOLD severity classification and were divided into frequent exacerbation (FE) group (≥2 times/year) and non-frequent exacerbation (NFE) group (<1 time/year) according to acute exacerbation (AE) times in the previous 12 months before the visit. The serum IL-8, IL-6, tumor necrosis factor (TNF)-α, and superoxide dismutase levels were measured by the enzyme-linked immunosorbent assay technique.

RESULTS

Serum IL-8 levels increased sequentially from controls [9.45 pg/mL (ranged: 6.85-38.4)], to stable [51.60 pg/mL (ranged: 22.4-131.1)], and exacerbation stage [129 pg/mL (ranged: 57.7-374)]. The level of serum IL-8 was significant higher in patients with FE than that of patients with NFE (209.0 pg/mL (ranged: 115-472) vs 65.6 pg/mL (ranged: 11.2-149.3), P=0.008). A receiver operating characteristics curve (ROC) generated to evaluate IL-8, IL-6, and TNF-α levels to discriminate between patients with and without exacerbation showed that the total area under the curve (AUC) was 0.71 (95% confidence interval (CI): 0.5764-0.8381; P=0.003), 0.54 (95%CI: 0.4048-0.6943; P=0.54), and 0.52 (95%CI: 0.3912-0.6656; P= 0.7).

CONCLUSION

Serum IL-8 is a sensitive, easy-to-measure, and inexpensive biomarker to give an indication of the course of COPD during exacerbation, and is a target to be explored further as a predictor to distinguish the patients prone to exacerbation.

IL-8 predicts early mortality in patients with acute hypercapnic respiratory failure treated with noninvasive positive pressure ventilation

Background

Patients with Acute Hypercapnic Respiratory Failure (AHRF) who are unresponsive to appropriate medical treatment, are often treated with Noninvasive Positive Pressure Ventilation (NPPV). Clinical predictors of the outcome of this treatment are scarce. Therefore, we evaluated the role of the biomarkers IL-8 and GDF-15 in predicting 28-day mortality in patients with AHRF who receive treatment with NPPV.

Methods

The study population were 46 patients treated with NPPV for AHRF. Clinical and background data was registered and blood samples taken for analysis of inflammatory biomarkers. IL-8 and GDF-15 were selected for analysis, and related to risk of 28-day mortality (primary endpoint) using Cox proportional hazard models adjusted for gender, age and various clinical parameters.

Results

Of the 46 patients, there were 3 subgroup in regards to primary diagnosis: Acute Exacerbation of COPD (AECOPD, n = 34), Acute Heart Failure (AHF, n = 8) and Acute Exacerbation in Obesity Hypoventilation Syndrome (AEOHS, n = 4). There was significant difference in the basic characteristic of the subgroups, but not in the clinical parameters that were used in treatment decisions. 13 patients died within 28 days of admission (28%). The Hazard Ratio for 28-days mortality per 1-SD increment of IL-8 was 3.88 (95% CI 1.86–8.06, p < 0.001). When IL-8 values were divided into tertiles, the highest tertile had a significant association with 28 days mortality, HR 10.02 (95% CI 1.24–80.77, p for trend 0.03), compared with the lowest tertile. This correlation was maintained when the largest subgroup with AECOPD was analyzed. GDF-15 was correlated in the same way, but when put into the same model as IL-8, the significance disappeared.

Conclusion

IL-8 is a target to explore further as a predictor of 28 days mortality, in patients with AHRF treated with NPPV.