Obstructive Lung Diseases: COPD Exacerbations |

Application of Parametric Model in Mortality Risk Analysis of Patients with Severe COPD in ICU FREE TO VIEW

Ying Sun; Hangyong He, MD; Qingyuan Zhan, MD
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Chian Meitan General Hospital, Beijing, China

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;149(4_S):A360. doi:10.1016/j.chest.2016.02.375
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SESSION TYPE: Original Investigation Poster

PRESENTED ON: Saturday, April 16, 2016 at 11:45 AM - 12:45 PM

PURPOSE: To evaluate the mortality risk factor of patients with severe COPD in ICU by utilizing the parametric model in survival analysis and to estimate patients' prognosis based on the risk function and survival function generated by the model.

METHODS: The clinical data and outcomes of COPD patients admitted into respiratory intensive care units (RICUs) at Beijing Chaoyang Hospital from January 2009 to June 2014 were retrospectively collected. According to the clinical outcomes, these patients were divided into improvement group and death group. A univariate analysis was conducted to screen out statistically significant variables. According to the distribution characteristics of these data, residual plots were prepared for the exponential model, Weibull model and Gamma model. It was found that Gamma model was the best fitted one for these data. Thus, using Gamma model as the analytical tool, those variables with differences obtained from the univariate analysis were plugged into Gamma model to work out the mortality risk factor of patients. Moreover, the risk function and survival function were generated according to the parametric model.

RESULTS: A total of 160 patients (111 were improved and 49 died) were collected according to the inclusion and exclusion criteria. The univariate analysis showed that compared with the improvement group, the death group had higher CCI score, body temperature, white blood cell count, proportion of neutrophil, serum creatinine level and pH level, lower resting carbon dioxide pressure (PCO2), and more concurrent invasive pulmonary aspergillosis (IPA). A further analysis by including the Gamma model revealed that concurrent or unconcurrent IPA, white blood cell count, pH level and PCO2 were associated with patients' mortality risk, and that the predicative value (PV) of patients' mortality risk = 2.8655-0.4070×IPA-0.0048×WBC-0.0049×pH+0.0097×PCO2. Moreover, the survival function formula was obtained according to the Gamma model: S(x) = 1-I (0.7507 x, -3.3773), where I was an incomplete gamma function.

CONCLUSIONS: Concurrent IPA is an important risk factor for patients with severe COPD in ICU, while increased white blood cell count, higher pH level and lower PCO2 level are also the risk factors for the death of patients with severe COPD.

CLINICAL IMPLICATIONS: This is good for clinical staffs to determine therapeutic regimen and perform prognosis assessment for the purpose of lowering the mortality rate of COPD patients.

DISCLOSURE: The following authors have nothing to disclose: Ying Sun, Hangyong He, Qingyuan Zhan

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