Study of Factors Affecting Platelet Count Following Liver Transplantation

Abstract

Patients with advanced liver cirrhosis have a complex hemostatic disturbance. Thrombocytopenia is one of the common features of this derangement. The pathogenesis of thrombocytopenia is complex; splenic pooling, increased platelet consumption and/or impaired production have been variably suggested to contribute as etiologic factors (Zwicker and Drews, 2007). Liver transplantation is the only treatment for end stage liver disease, but even after transplantation thrombocytopenia is frequent, and during the first post-operative week a moderate reduction in platelet count (20,000–50,000/mcl) occurs in about half of the patients, and counts below 20,000/mcl are reported in about 8% of patients. Spontaneous resolution usually begins during the second week, and by the third week platelet count reaches or exceeds the levels measured before liver transplantation (Richards et al., 1997). Persistence of thrombocytopenia complicates the postoperative course by causing an increased bleeding tendency, infection, and a higher incidence of morbidity after liver transplant (Ben Hamida et al., 2003) , and therefore worsens the prognosis of the transplanted patients (McCaughan et al., 1992). Furthermore, the platelet count is one of the crucial determinants for discontinuation of interferon therapy used preemptively or as treatment for recurrent hepatitis C virus (Shergill et al., 2005 and Gordon et al., 2009).

The aim of this study was to monitor changes in platelets count following liver transplantation, identify possible factors contributing to persistence of thrombocytopenia. The study was conducted on patients with end stage liver disease who are listed for LDLT in Ain Shams Center of Organ Transplantation (ASCOT). Adult patients who underwent LDLT surgery in the period from January 2012 to December 2012 were included and followed up for one year. Study Design:

All patients had their preoperative platelet count recorded. Following transplant, platelets count was recorded daily for the first two weeks, then at one month, 3 months, 6 months and 12 months. Splenic size and portal venous blood flow were measured at the same intervals by doppler ultrasound. Thrombopoietin (TPO) was measured for all patients included in the study before surgery then at 2 weeks (early) and 6 months (late) following transplantation. Thrombocytopenia was defined as a platelet count of less than 150 x 109/L, persistent thrombocytopenia was defined as thrombocytopenia at 1 year post-transplantation. At the end of the study, patients were divided into two groups: • Group I: patients with persistent thrombocytopenia at 1 year. These were 20 patients (56%). • Group II: patients with no thrombocytopenia at 1 year. These were 16 patients (44%).

Factors that showed significant correlation with postoperative thrombocytopenia were: Preoperative portal vein flow velocity, duration of the operation, preoperative platelet count, GRWR, preoperative spleen size, preoperative AST and preoperative WBC. All statistically significant data obtained by univariate analysis were compared on ROC curve to obtain their sensitivity and specificity as predictors of post-transplant thrombocytopenia. Highest sensitivity was found for preoperative portal flow velocity and highest specificity was to GRWR. The curve also showed that preoperative platelet count, operative duration and GRWR have highest positive predictive values. Multivariate analysis was done to obtain the predictors of post-transplant persistant thrombocytopenia which revealed that preoperative platelet count, operative time, preoperative AST level, and preoperative PV flow velocity were independent predictors of postoperative persistent thrombocytopenia.