Since the first human liver transplant in 1963 [1] orthotopic liver transplantation (OLT) is now established as the only definitive treatment for patients with end-stage liver disease (ESLD). In the US and Western Europe liver cirrhosis due to viral hepatitis B or C, alcohol abuse, hepatocellular carcinoma or genetic disorders like hemochromatosis are the main indications for OLT [2].

According to the United Network for Organ Sharing (UNOS), the 1-year and 5-year survival rates of patients undergoing OLT are 85% and 75%, respectively [3]. However, the 1-year survival rate after liver transplantation is only about 60% for those who are critically ill at the time of the surgery. A significant increase in survival rates after OLT could be achieved by the introduction of novel immunosuppressive drugs like calcineurin inhibitors, mycophenolate mofetile and mTOR inhibitors and the overall more experience with the procedure [4].

The highest mortality rate is observed within the first year after OLT due to early graft failure due to preexisting disease of the donated organ or technical complications during surgery such as revascularization [5]. Another major clinical problem after OLT is infection: infections are one of the leading causes of morbidity and mortality in liver transplant recipients [6]. More than two-thirds of liver transplant recipients have infections in the first year after transplantation, and in up to one-third of organ transplant recipients infections are the leading cause of death [6,7]. In addition, release of cytokines during the infection may have other indirect and negative effects, including allograft injury, opportunistic superinfection, and malignancy [7].

C-reactive protein (CRP) is a protein, which is synthesized by the liver in response to cytokines released by macrophages and adipocytes [8]. Procalcitonin is a peptide precursor of calcitonin. It is produced by parafollicular cells also called C cells of the thyroid gland and by neuroendocrine cells of the lung and the intestine. In contrast to CRP, PCT is produced independently from the liver function. PCT is a marker for severe bacterial sepsis [9].

We here investigated whether different parameters of infection including the inflammatory markers CRP, PCT and WBC predict post-OLT mortality, graft loss and rate of acute rejection.

In this single-center analysis we retrospectively reviewed 102 adult patients who underwent OLT between January 2011 and December 2012 at the Hannover Medical School, Germany. All patients under 18 were excluded. All adult patients were stratified by i) patient survival, ii) graft survival and iii) episode of rejection(s) and were followed from OLT for one year. Laboratory data including CRP, PCT and WBC of the peri transplant period (0-4 days after OLT) were analysed.

Patient demographics were collected from the electronic medical records of the Hannover Medical School. LabMELD was calculated as previously described directly before OLT.

Patient and graft survival as well as episodes of rejection and other severe adverse events as well as primary graft non-function were recorded. Other recorded clinical outcomes included the need for re-transplantation, the duration of time spent on intensive care unit (ICU) and in hospital.

The primary clinical outcomes included graft and patient survival one year after OLT and duration of stay on ICU and in hospital.

Ethical aspects

This study was based on hospital databases and patient medical histories and was performed in accordance with the principles stated in the Declaration of Helsinki. The study had been approved by the ethics committee of Hannover Medical School, Germany.

Software and statistical analyses

Data were analyzed using Excel (MS Office 2010, Microsoft Corp., Redmond, WA, USA). Unpaired two-sided student’s t-test was performed accordingly to determine significance. A p-value of less than 0.05 was considered to indicate statistical significance.

Clinical characteristics

Between January 2011 and December 2012, a total of 102 adult patients underwent OLT. The clinical characteristics of these patients are shown in Table 1. Mean age at the time of OLT was 49 years (range 20-73 years). 45 out of 102 patients were female (44%) and 94 patients were Caucasian (92%). The main indication for liver transplantation was cirrhosis due to viral hepatitis B or C (21.6%) followed by primary sclerosing cholangitis (19.6%). Overall, 22 patients had hepatocellular carcinoma (HCC). Median labMELD score at time of OLT was 20 (range 6-40).

Table 1: The clinical characteristics of the patients.

Clinical outcome

54 out of 102 patients showed no signs of an acute rejection episode within one year after OLT (52.94%) (Table 2). 48 had at least a mild rejection and were treated with steroid bolus therapy or a change in the immunosuppressive regimen. There was no significant difference in age (51.1 versus 49.6 years), sex (44.4% versus 43.75% female) and labMELD (20 versus 19.3) at time of OLT the group of patients with an acute rejection episode in comparison to patients without any rejection (Table 3). Patients with a CsA-based immunosuppression had at least a slightly higher rate of acute rejection than patients with a tacrolimus-based immunosuppression: 75% of all patients who developed an acute rejection were treated with CsA while only 66% of patients who did not develop an acute rejection were treated with CsA. Interestingly, addition of steroids to the immunosuppressive regimen had no influence on the rate of rejection: 18.75% of patients with at least one episode of an acute rejection were not treated with steroids, while 25.6% in the group of patients without rejection had a steroid-free immunosuppressive regimen (Table 3).

Table 2: Clinical outcome of patients.

Table 3: comparison of acute rejection in to without any rejection patients.

At least in our cohort, patients with an acute liver failure seems to have a slightly higher risk to develop an acute rejection within the first year after OLT (64% develop an acute rejection), while other underlying liver diseases such as viral hepatitis and autoimmune hepatitis or primary sclerosing cholangitis do not have any influence on the rejection rate. Only 25% of patients with polycystic liver disease had an acute rejection.

16 out of 102 patients die within one year after OLT (15.6%) (Table 2). The main reason for death was severe infection leading to sepsis and multiorgan failure (87.5%): while 3 patients suffered from cholangiosepis, one patient died due to CMV encephalitis. Two patients developed aspergillosis of the lung (Table 4). Eight patients died due to bacterial sepsis. Two patients died due to severe intracerebral bleeding. As expected, patients who did not survive the first year after OLT were significant older than patients, who survived (53.9 years versus 48.2 years, p<0.05). Interestingly, labMELD at time of OLT was no risk factor for one-year patients survival in our cohort (22.1 versus 19.3 points, p=0.34). In addition, we were not able to detect any correlation between the underlying liver disease and rate of one-year survival of the patients as well as type of immunosuppressive regimen (Table 4). However, there was a trend that patients with alcoholic liver cirrhosis have a lower survival rate after one year since 31.3% of the deceased patients were former alcohol addicted. Six patients needed a re-transplantation within one year (5.88%) and out of these patients four died afterwards.

Table 4: correlation between the underlying liver disease and rate of one-year survival of the patients.

Next, we evaluated the overall one-year graft survival in our cohort. 20 out of 106 patients lost their graft within one year after OLT (18.86%) (Table 2). Six patients had to undergo re-OLT due to initial non-function of the graft (5.9%). Out of these patients, only four survived for more than one year.

Overall, the median stay at the hospital was 45.77 days and median stay on the intensive care unit (ICU) was 30.6 days. The median stay at hospital and ICU was significantly longer in the group of patients who died within one year after OLT (p< 0.001 for both terms).

Most of the patients in our cohort died due to severe viral, fungal or bacterial infections and its complications within one year after OLT. We therefore wanted to investigate the role of inflammatory markers like CRP, PCT and elevated WBC of more than 20.000/µl early after OLT that are associated with infection (Table 5). We were not able to detect any significant differences in CRP or PCT levels in the early phase after OLT in the group of patients that died or lost the graft within one year after OLT (p=0.3 or p=0.8 respectively). Interestingly, WBC early after OLT was significant higher in patients that died within the first year after OLT (p=0.019) and also in patients who lost their graft within one year after OLT (p=0.03). There was no correlation between the amount of WBC and the rate of rejections episodes. White blood cell count > 20.000/µl within the first four days after OLT was associated with a higher patient mortality and rate of graft loss. Patient mortality was 30% (WBC >20.000/µl) in comparison to 13% (WBC <20.000/µl). No correlation of WBC with the underlying liver disease or type of immunosuppressive regimen was determined (Table 5).

Table 5: factors associated with graft and patient survival.

In this retrospective single-center study we reported the one-year graft and patient survival after OLT. Overall, 84.4% of the patients survived for more than one year. The main reason for death within the first year after OLT was bacterial, viral or fungal infection leading to sepsis and multiorgan failure. Interestingly, an increase of WBC factors of more than 20.000/µl within the first four days after OLT was a significant risk factor for patient and graft loss, while an increase of CRP and PCT was no marker of survival.

WBC are important components in protecting us against infections. They are produced from hematopoetic stem cells in the bone marrow. Leukocytosis is a typical finding in patients with acute or chronic infection, but also after stress, convulsions or after anesthesia or epinephrine administration [10]. In contrast, immunosuppressive therapy based on calcineurin inhibition and/or mycophenolate mofetil often result in the decline of WBC [11]. Here we observed that an increase of WBC of more than 20.000/µl early after OLT was associated with patient and graft loss. One possible explanation for this observation might be that these patients develop signs of infection already in the very early phase after OLT, which is leading to their worse prognosis. Another possible explanation might be that elevated WBC can also be detected after stress. However, in our study all patients underwent the same procedure and duration of OLT was not significantly different within both patient groups. Importantly, in our cohort survival did not correlate with labMELD score at time of OLT. Last but not least also steroid administration can elevate WBC, however, we could not observe any correlation between use of steroids as part of immunosuppressive regimen and rate of survival. Therefore we do not believe that leucocytosis is here in these cases mainly associated with stress or trauma. Also such a high increase of WBC due to anesthesia administration seems to be an unlikely explanation. We therefore believe that the early increase of WBC is an early and cheap marker for an early onset of severe infections after OLT. If an early antibiotic therapy or the escalation of antibiotic therapy in patients with more than 20.000 leukocytes/µl within the first four days after OLT might have a positive influence on patient and graft survival should be part of a prospective controlled study.

Interestingly, CRP and PCT elevation within the first four days after OLT did not correlate with patient survival and/or graft loss. One possible explanation might be that CRP is in general produced in the liver and that CRP production can be delayed in the graft, especially when the graft shows delayed or primary non-function. In contrast, PCT is produced in C cells of the thyroid gland and by neuroendocrine cells of the lung and the intestine [12,13]. However, PCT is more a marker for bacterial than for viral infections [14-16]. Furthermore, it is possible that we here did not detect any statistical significance because the maximal increase of PCT might be at a later than fours days after OLT.

We also observed several cases of death due to cholangiosepsis. A possible explanation might be that in our center PSC was one of the leading indications for OLT. Patients with PSC have in general more frequently problems with bacterial infection of the bile ducts than patients with other underlying liver diseases [17,18]. If it might be useful to take samples of the bile duct for microbiological tests during OLT should be investigated in further studies.

Interestingly, it has been shown by several other studies that lymphopenia is a prognostic marker for survival after trauma [19] or in patients with advanced carcinomas; sarcomas [20], differential blood counts were not available from our patients since it does not belong to a routine testing on our transplant intensive care unit. In addition, Fernandez-Ruiz et al. found out that pre transplant lymphocyte count can predict the incidence of infection during the first two years after OLT. Unfortunately, perioperatively differential blood counts were not available from our patients since it does not belong to a routine testing on our transplant intensive care unit. However, in our cohort absolute leukocyte count was associated with overall patient mortality.

The present study has some limitations: the size of the study cohort, the inhomogenous distribution and the retrospective design. However, this is the first single center study investigating WBC early after OLT in a real world setting. Indeed, the influence of WBC count on survival early after OLT should be restudied by multicenter studies. Future investigations should also include differential blood counts early after OLT. This might help to further characterize our finding an to confirm that bacterial, viral and/or fungal infection are responsible for the increased mortality after OLT.

In summary, these data demonstrate that white blood cell counts >20.000/µl early after OLT might be a cheap and simple prognostic marker for patient and graft survival, while elevated PCT and CRP early after OLT showed no significant correlation.