Significance Of Dynamic Monitoring PCT In Patients With Bacterial Hospital Acquired Pneumonia

BACKGROUND AND AIM:Hospital acquired pneumonia is a nosocomial infection, whose main pathogenic bacterias are Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Acinetobacter. The incidence rate of HAP is up to1.3%-3.4%in our country, which is ranking frist in world(Accounted for29.5%), while the mortality rate is also high. At present, how to solve the problem of the bacterial drug resistance is a hot topic, of which the most important is the reasonable use of antibiotics and the control of nosocomial infection. The America Thoracic Society emphasized appropriate antimicrobial drugs and sufficient dose in the early treatment on HAP’s guideline in2005in order to reduce the use of antibiotics and the genernation of resistant bacteria. However, the diagnostic gold standard and method of predicting prognosis for HAP should still be further clarified.Pugin proposed a clinical scoring systems,called "clinical pulmonary infection score ",to stratify patient with HAP, but its sensitivity and specificity of this system is low and the prognostic value of HAP is not high.It has been reported that the AUC of CPIS to predict VAP is0.581. Therefore, it is important and necessary to find a high specificity biomarker for bacterial infection to guide the application of antibiotics. Although, CRP is also thought to be a biomarker of inflammatory reaction, its clinical use is limited due to its low specificity and can be affected by many infection or non-infection factors.Nowadays, it is believed that procalcitonin (PCT) is a more sensitive and more specific markers of inflammation than CRP. PCT is one of the calcitonin precursors, transformed from PPCT in calcitonin thyroid C cells. Under normal physiological conditions, the level of PCT which can be detected in blood is very low. But in the case of infection, especially in bacterial infection, serum PCT concentration would increased significantly. Currently, PCT is mainly used to distingish bacterial and non bacterial infection and to guide antibiotic therapy. One of the most studies is the value of PCT in the diagnosis and treatment of respiratory tract infections. Some foreign researchers believed that the level of PCT in patients with bacterial lower respiratory tract infection was significantly higher than that of in non-infected patients, and its level depends on the severity and prognosis of disease. Furthermore, some studies even thought that PCT is closely related to the severity of VAP patients. However, most of those studies were focusing on community acquired pneumonia or just ventilator-associated pneumonia patients admitted to ICU.Therefore, wether the level of serum PCT and its change after treatment are relate to HAP needs further study. In this study, taking patients with HAP(including severe and non severe) as the research object, we evaluated the relationship between the dynamic changes of PCT and the prognosis of patients with bacterial HAP by retrospective analysis.Methods:l.ObjectivesPatients with hospital acquired pneumonia and non infected patients were enrolled during hospitalization in the Department of respiration of Zhuhai People’s Hospital from Jan2012to Jan2013, two kinds of method for diagnosing criteria were recommended by the USA Thoracic Society recommendations in the new guidelines, namely clinical diagnosis method and microbiological diagnosis method.Exclusion criteria:patients with myocardial infarction, cardiac arrest, acute pancreatitis, endocarditis, meningitis, arthritis, trauma and operation history or Legionella, mycoplasma, viral, fungal infection in the recent were excluded.2.Case collectionWe checked the electronic medical records to collecte patient datas. According to the guideline of the USA Thoracic Society recommendations, patients with hospital acquired pneumonia were selected as HAP group, and non infected patients were selected as control group. According to patients’survival situation in one year, patients with hospital acquired pneumonia were divided into non-survival group and survival group; On the other hand, according to the PCT’s decline, patients were divided into "decline of PCT value≥80%" and the "decline of PCT<80%or the continuing hold or even rise" groups.There were113patients in HAP group, with the average age of69.5years old,85male. In the non-survival group, there were64patients, with the average age of72years old,52male,the average hospital stay was57days,59patients with ventilator, and56patients had basic diseases,for example COPD; in the survival group,there were49patients, with the average age of67years old,33male,the average hospital stay was59days,25patients with ventilator, and38patients had basic diseases; In the control group,there were68patients, with the average age of66years old,46male,the average hospital stay was12days, no patient with ventilator, and39patients had basic diseases.The age and sex of HAP group and control group had no significant difference, the P values were0.11and0.27. There were no significant difference between the non-survival group and survival group in age and body temperature, white blood cell count, neutrophil percentage.3. The diagnosis standard of hospital acquired pneumoniaClinical diagnosis method:Patients with new or progressive exudative shadow of Chest X-ray and at least two clinical infection symptoms (fever for more than38℃or less than35.5℃temperature does not rise, leucocyte increase or decrease, purulent secretions), can be considered as a HAP.Microbiological diagnosis method:The lower respiratory tract secretion was collected to culture. After cultivation, if the bacteria concentration was above the threshold, HAP would be diagnosised. Otherwise, it was considered as a parasitic or bacterial contamination.(Diagnostic reference value of ETA is≥105～6cfu/ml. Diagnostic reference value of BAL is104或105cfu/ml. Diagnostic reference value of PSB is103cfu/ml or more.)4. Procalcitonin measurementsProcalcitonin measurements were obtained the day when HAP was diagnosised (DO) and seventh days after treatment(D7), collecting4ml venous blood for PCT testing respectively.DO was the initial value. While in the control group patients’ blood was collectd on the day of admission. The serum PCT value was detected by micro sandwich immunoassay quantitative detection.5. Statistical analysisData were analyzed with SPSS13.0software. We compared the initial value of PCT from the HAP group and control group by Wilcoxon rank sum test method. The diagnostic value of initial PCT value to predict HAP was determined through the construction of the corresponding receiver operating characteristic (ROC) curve. The relationship between the initial PCT value and hospital stay and the use of ventilator days were analysis by Pearson correlation analysis. We compared the initial value of non-survival group and survival group by Wilcoxon rank sum test method.The diagnostic value of initial PCT value to predict mortality of HAP patients was determined through the construction of the corresponding receiver operating characteristic (ROC) curve. The relationships between the difference PCT decreased after treatment and the length of hospital stay and the use of ventilator days were analysised through Mann-Whitney U analysis. The relationships between the decline proportion of PCT after treatment and the length of hospital stay and the use of ventilator days were analysised through Mann-Whitney U analysis. To compare the survival rate between the "decline of PCT value=80%"group and the "decline of PCT<80%"group, we drew the survival curves of this two groups. The month survival rates of these two groups were compared with Log-rank test. The two groups and WBC, neutrophil percentage, gender, age, body temperature were screened and predictive by COX proportional hazards model.Results:1.Comparision of the initial PCT value with HAP group and normal control group P=0.034, P<0.05, it can be considered that the initial PCT of HAP group were significantly higher than that in the control group.2. Receiver operating characteristic (ROC) curve of initial PCT value to predict the occurrence of HAP.A cut-off value of0.009ug/L provides sensitivity and specificity of87.6%and75%, respectively, the area under the curve was0.887.3.Comparision of the initial PCT value with the non-survival group and survival groupP=0.001, P<0.05, it can be considered mat the initial PCT of non-survival group were significantly higher than that in the survival group.4.The relationship between the initial PCT value and the length of hospital stay and the use of ventilator days The Pearson correlation coefficient was-0.113and-0.089, P value was0.235and0.350, suggesting that there was no significant correlation between initial PCT value and the length of hospital stay and and the use of ventilator days.5.Receiver operating characteristic (ROC) curve of initial PCT value to predict mortality of HAP patientsA cut-off value of0.735ug/L provides sensitivity and specificity of66%and70%, respectively, the area under the curve was0.714,suggesting that there was litte value of initial PCT to predict mortality of HAP patients in one year.6.The relationships between the difference PCT decreased after treatment and the length of hospital stay and the use of ventilator daysThe Pearson correlation coefficient was-0.046and-0.052, P value was0.629and0.583, suggesting that there was no significant correlation between the difference PCT decreased after treatment and the length of hospital stay and and the use of ventilator days.7.The relationships between the decline proportion of PCT after treatment and the length of hospital stayP=0.235,suggesting that there was no significant correlation between the decline proportion of PCT after treatment and the length of hospital stay.8.The relationships between the decline proportion of PCT after treatment and the use of ventilator days.P=0.000,suggesting that the use of ventilator days between the "decline of PCT value≥80%"group and the "decline of PCT<80%"group were significantly different,the days of the former group patients uesing ventilator were longer.9.The comparision of1years survival rate between the"decline of PCT value≥80%"group and the "decline of PCT<80%" group.We drew the Kaplan-Meier survival curve of the two groups,and use Log-rank test to compare. P value<0.01, suggesting that the survival rate of the two groups were significantly different, the survival rate of "PCT decreased more than80%" group was higher.10.Multivariate COX regression analysisThe two groups and WBC, neutrophil percentage, gender, age, body temperature were screened and predictive by COX proportional hazards model. PCT decreased≥80%after treatment were the independent protective factors of HAP patients with death outcome in1years.