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Predictive models play a pivotal role in the provision of accurate and useful probabilistic assessments of clinical outcomes in chronic diseases. This study was aimed to develop a dedicated prognostic index for quantifying progression risk in chronic obstructive pulmonary disease (COPD). Data were collected prospectively from 75 COPD patients during a three years period. A predictive model of progression risk of COPD was developed using Bayesian logistic regression analysis by Markov chain Monte Carlo method. One-year cycles were used for the disease progression in this model. Primary end points for progression were impairment in basal dyspne index (BDI) score, FEV(1) decline, and exacerbation frequency in last three years. Time-varying covariates age, smoking, body mass index (BMI), severity of disease according to GOLD, PaO2, PaCO(2), IC, RV/TLC, DLCO were used under the study. The mean age was 57.1 + or - 8.1. BDI were strongly correlated with exacerbation frequency (p= 0.001) but not with FEV(1) decline. BMI was found to be a predictor factor for impairment in BDI (p= 0.03). The following independent risk factors were significant to predict exacerbation frequency: GOLD staging (OR for GOLD I vs. II and III = 2.3 and 4.0), hypoxemia (OR for mild vs moderate and severe = 2.1 and 5.1) and hyperinflation (OR= 1.6). PaO2 (p= 0.026), IC (p= 0.02) and RV/TLC (p= 0.03) were found to be predictive factors for FEV(1) decline. The model estimated BDI, lung function and exacerbation frequency at the last time point by testing initial data of three years with 95% reliability (p0.001). Accordingly, this model was evaluated as confident of 95% for assessing the future status of COPD patients. Using Bayesian predictive models, it was possible to develop a risk-stratification index that accurately predicted progression of COPD. This model can provide decision-making about future in COPD patients with high reliability looking clinical data of beginning.

Summary Rationale To evaluate bacterial colonization and the airway inflammatory response, and its relationship to the frequency of exacerbation in patients with stable chronic obstructive pulmonary disease (COPD). Methods Quantitative bacteriologic cultures, neutrophil elastase, myeloperoxidase (MPO), tumor necrosis factor alpha (TNF- α ) and interleukin (IL)-8 were measured in bronchoalveoler lavage (BAL) in 39 patients with stable COPD [19 with frequent exacerbation (⩾3/year), and 20 with infrequent] and in 18 healthy controls (10 smokers and 8 non-smokers). Results BAL revealed the microorganisms with potential pathogenicity above the established threshold (⩾10 3 cfu/ml) in 68.4% of patients with frequent exacerbation, 55% of infrequent exacerbation, 40% of smokers and 12.5% of non-smokers controls ( P = 0.05 ). BAL MPO, IL-8 and TNF- α levels were found to be significantly higher in COPD as compared to controls ( P = 0.001 ). However, only IL-8 level was significantly higher in COPD patients with frequent exacerbation as compared to infrequent ( P = 0.001 ). Airway bacterial load correlated with levels of airway inflammation markers in COPD ( P 0.05 ). Conclusion The bacterial load and airway inflammation contributes to each other in stable COPD. However, there is a link only between interleukine (IL)-8 and frequent exacerbations. Clearly, the relationship between bacterial colonization, airway inflammation and frequent exacerbations is of major importance in understanding of the COPD pathogenesis.