Evaluation Study Of Platelet Counts Change In Prognosis Of Severe Pneumonia

Objective:To investigate the value of platelets change in the prognosis of patients with severe pneumonia?SP?.Methods:A case-control study was conducted to retrospectively analyze adult SP patients admitted to Sichuan Provincial People's Hospital from October 2014 to October 2018.Demographic data,basic diseases,laboratory tests,treatment measures,pathogenic bacteria and other relevant clinical data were collected.Divided into survival and death groups by outcome during hospitalization,t test,the Mann-Whitney U test,?²test were used to compare the differences between the two groups of clinical features,platelets changes in the first 10 days after admission were compared also.Then,independent risk factors of death were analyzed by binary logistic regression.The area under curve was obtained by drawing ROC curve,maximum Youden index was calculated and the cut-off value with the highest prediction rate was obtained.Results:301 patients with SP were enrolled,including 191 patients in the survival group and 110 patients in the death group?36.54%?.The average age was 71.43±12.39 years.The main basic disease was chronic lung diseases with a proportion of 65.78%.There was no significant difference in platelet counts between the death group and the survival group at admission.Comparison groups,white blood cell?WBC?,?PC?PC on discharge minus PC on admission,C-reactive protein?CRP?,Procalcitonin?PCT?,brea nitrogen?BUN?,Lactate?Lac?,invasive mechanical ventilation?IMV?,CURB-65 score,pneumonia severity index?PSI?,and APACHE II score were higher in the death group than those in survival group,The platelet counts and Alb in the death group was significantly lower than that in the survival group.and the difference was statistically significant?P<0.05?.Gram-negative bacteria were the main pathogens in SP patients.The top three pathogens were acinetobacter baumannii?21.77%?,pseudomonas aeruginosa?15.50%?and klebsiella pneumoniae?14.39%?.The detection rate of acinetobacter baumannii in the death group was significantly higher than that in the survival group.Base on logistic regression analysis,it showed that the APACHE II score?OR=1.18;95%IC=1.109?1.259???PC[OR?For each 50x 10 ⁹/L increment?=OR=1.98;95%IC=1.505?2.604?]and invasive mechanical ventilation?OR=4.525;95%IC=2.392?8.559?are independent risk factors affecting the prognosis of SP patients?P<0.05?.The ROC curve analysis revealed that,the area under the curve?AUC?of APACHEII score,?PC,invasive mechanical ventilation,APACHE II score+?PC+invasive mechanica ventilation were 0.789?95%IC=0.739?0.840??0.766?95%IC=0.708?0.825??0.717?95%IC=0.656?0.779??0.866?95%IC=0.822?0.910?respectively.The cut-off value of the APACHE II score was 18 points.The sensitivity and specificity of death were 82.7%and 64.4%,respectively.the positive predictive value and negative predictive value were 86.6%and57.2%,respectively.The cut-off value of platelet decrease compared with admission was 51×10⁹/L,the sensitivity and specificity of death were 61.8%and 86.4%,respectively,the positive predictive value and negative predictive value were 79.7%and 72.3%respectively.59 patients had platelet counts during the first 10 consecutive 10 days after admission.By comparing the death group and the survival group,it was found that there was a significant difference in PC between the two groups from the 7th day after admission,and the death group had a lower PC than that in survival group.160 patients had platelet counts on the day of admission and the third day after admission.The rate of platelets change on day 3 was calculated,?PC₃%=?PC on the day of admission–PC on the third day after admission?/PC on the day of admission,By comparing the two groups,It was found that the rate of early platelet decline in the death group was significantly higher than that in the survival group?P<0.05?.Conclusions:1.Platelet counts decline was more predictive of risk for severe pneumonia than baseline platelet counts level.Platelet counts decline is an independent risk factor for in-hospital death in SP patients,platelet counts decline indicated a poor prognosis in patients with severe pneumonia.2.Platelet counts decreased to 51×10⁹/L compared with admission can be used as the best cut-off value to evaluate the death of SP patients.Monitoring on platelet should be strengthened during hospitalization.Combined with invasive mechanical ventilation and APACHE II score,the mortality rate prediction was increased.