中文摘要：

目的分析老年下呼吸道细菌性感染患者血清降钙素原（PCT）水平检测的诊断、预后判断价值，为指导临床治疗、评估疗效提供依据。方法选取医院2010年8月一2013年8月收治的371例老年患者，观察其下呼吸道细菌性感染发生情况，并分为感染组及非感染组，按照感染组患者预后分为良好组及较差组，比较各组患者血清PCT水平差异。结果371例老年患者有69例发生下呼吸道细菌性感染，感染率18．6％；69例患者经治疗后预后良好31例占44．9％，较差38例占55．1％；感染组血清PCT水平显著高于非感染组（P〈0．05）；预后良好组人院1、8d血清PCT水平均显著低于预后较差组（P〈0．05）；血清PCT对感染诊断的灵敏度为72．3％、特异度为68．5％，对预后判断的灵敏度为96．4％、特异度为97．0％；相关性分析显示，血清PCT水平与患者APACHEⅡ评分呈显著正相关（r=0．366，P〈0．05）。结论血清PCT在老年下呼吸道细菌性感染的诊断和预后判断中均具有良好的指导意义，值得临床广泛推广采用。

英文摘要：

OBJECTIVE To analyze the value of serum procalcitonin （PCT） testing in diagnosis of lower respiratory tract bacterial infections in the elderly patients and in evaluation of prognosis so as to provide guidance for clinical treatment and evaluation of effectiveness. METHODS A total of 371 elderly patients who were treated in the hospital from Aug 2010 to Aug 2013 were enrolled in the study, then the incidence of lower respiratory tract bacterial infections was observed, the subjects were divided into the infection group and the non-infection group and divided into the good prognosis group and the poor prognosis groups the serum PCT levels were observed and compared. RESULTS Of the 371 elderly patients, the lower respiratory tract bacterial infections occurred in 69 cases with the infection rate of 18.6%. Among the 69 patients, 31 cases had good prognosis, accounting for 44, 9%, and 38 cases had poor prognosis, accounting for 55.1% ; the serum PCT level of the infection group was significantly higher than that of the noninfection group （P〈0.05）. The serum PCT levels at day 1 and 8 admission to the hospital were significantly lower in the good prognosis group than in the poor prognosis group （P〈0.05）. The sensitivity of serum PCT in diagnosis of infections was 72.3%, the specificity 68. 5%2 the sensitivity in determination of prognosis was 96.4%, the specificity 97.0%. The correlative analysis indicated that the serum PCT level was positively correlated with APACHE Ⅱ score （r= 0. 366,P〈0.05）. CONCLUSION The serum PCT testing has great significance in diagnosis of lower respiratory tract infections in the elderly patients and in determination of prognosis, and it is worthy to be promoted in the clinical practice.