The Value Of Detecting Serum PCT Level During The Perioperative Period Of Primary Hip And Knee Arthroplasty

ObjectivePostoperative infections associated with implants are one of the most challenging complications after arthroplasty.Any type of infection,including pneumonia,urinary tract infections(UTI)and superficial surgical site infections(SSI)should be cured during the perioperative period of arthroplasty and may lead to periprosthetic joint infection.Biomarkers,such as white blood cell count(WBC),interleukin-6(IL-6)and C-reactive protein(CRP)may be used to aid in the diagnosis,therapeutic monitoring and risk stratification.However,these blood parameters lack sensitivity and specificity in discriminating inflammation due to a bacterial infection from that of a surgical injury response.Previous studies have reported that due to its high specificity,procalcitonin(PCT)is comparatively more useful for diagnosing bacterial infections.PCT has been shown to be a more accurate marker in detection of early postoperative infection.PCT typically increases 2 to 4 hours following an appropriate exposure such as sepsis;it reaches its peak after 6 hours and has a half-life of 25-30 hours.The present research included prospective and retrospective methods.We aimed to characterize the baseline of serum PCT levels in patients undergoing arthroplasty and to determine the cut-off value that may represent perioperative pneumonia,urinary infections and superficial surgical site infections.Secondary objectives included looking the specificity and the sensitivity at the characteristics of PCT in diagnosing infections during the perioperative period of arthroplasty.MethodsRetrospective study:The present retrospective study included a total of 500 patients treated between July 2014 and August 2015.The case group contained 25 patients with perioperative infections(4 pneumonia,7 urinary and 14 superficial surgical site infections),and the control group contained 25 patients without any post-surgical complications.Serum levels of PCT and WBC were measured.And the sensitivity,specificity and predictive value of these parameters were assessed.Prospective study:This observational study included 73 patients undergoing primary hip and knee arthroplasty.Infection was diagnosed in 9(12.33%)of 73 patients and involved the pneumonia(one),urinary(two)and superficial surgical site infection(six).Serum PCT,and IL-6 were measured.The sensitivity,specificity and predictive values of PCT and IL-6 were assessed.Statistical analysisDescriptive data analyses were carried out with Statistical Package for Social Sciences software,version 19.0 for Windows.A box plot was used to display the distribution range of PCT levels.Using the Receiver-Operator-Characteristics(ROC)curves to measure the best cut-off values and calculated individual specificity and sensitivity of PCT.ResultsRetrospective study:In the control group,the PCT levels at D4(0.062±0.020 ng/ml)were 2-fold of the mean baseline value,followed by a decrease until D6(0.051±0.019 ng/ml)and a return close to the normal range by D8(0.032±0.015 ng/ml).The PCT levels in the case group had rapidly increased on D4(0.510±1.208 ng/ml).They continuously increased on D6(0.527±1.360 ng/ml)and D8(0.686±1.117 ng/ml).From a clinical point of view,infection events were indicated in these patients during post-operative follow-up.For PCT,the area under the receiver operating characteristic curve(AUC)was 0.978[95%confidence interval(CI),0.933-1.022],and for WBC,the AUC was 0.562(95%CI,0.398-0.0.726).For PCT,the cut-off point of 0.0995 ng/ml was associated with a sensitivity of 96%and a specificity of 100%.Prospective study:The level of PCT(0.086 ± 0.078ng/ml)increased rapidly on the fourth day(nearly 2-fold higher than baseline mean values).However,it dropped rapidly on the sixth day(0.061 ± 0.035 ng/ml)as returning close to the height of normal range.The level of PC in group 2 increased constantly on the sixth day.From the clinical point of view,the infection events can be found in these patients during postoperative follow-up.For PCT,the AUC was 0.967(95%CI,0.934-1.000),for IL-6 the AUC was 0.806(95%CI,0.754-0.859).For PCT,the cut-off point of 0.1385 ng/ml had a sensitivity of 93.3%and a specificity of 97.3%.Conclusion1.The serum concentrations of PCT peaked rapidly early post arthroplasty.Surgical trauma may have been the cause of the transient elevation of PCT.If no infection occurs,it willdrop rapidly to normal levels.The PCT trend may be used as a marker for possible infection in the early postoperative period.2.Based on the characterize of perioperative period infection and the variation of PCT,we proposed that detecting PCT on day 4 and day 6 may be more valuable in the diagnosis asepsis pathological changes in the preoperative period.It means that any significant elevations of PCT at day 6 may suggest an occurrence of infection or other inflammation.3.The aseptic pathological changes in hip and knee did not cause any significant increases in PCT,but cause a high-level IL-6 course.Detecting PCT may be more valuable than using IL-6 in the diagnosis sepsis pathological changes in the perioperative period.The sensitivity and the specificity of PCT in diagnosis of infection are higher than that of IL-6 and WBC diagnosis of septic pathological changes in the perioperative period.