Absolute Lymphocyte Count as a Prognostic Factor for Cytomegalovirus Infection After Heart Transplantation

Abstract

<h3>Purpose</h3> Previous studies have suggested a correlation between reduced absolute lymphocyte count (ALC) & cytomegalovirus (CMV) infection and have therefore highlighted the potential of ALC as a simple tool to predict CMV infection in transplant patients. This study aims to examine the prognostic value of ALC on CMV infection in heart transplant patients. <h3>Methods</h3> Clinical information and ALC data of all adult patients who received orthotopic heart transplantation between January 2004 and May 2019 were collected. We performed a multivariable Cox regression model that incorporates repeated measurements of ALC as a time-varying continuous prognostic factor in two ways, first as binary variable with a threshold of 610 cells/μL and secondly as a continuous variable. Furthermore, landmark analyses to evaluate the mean ALC level of the preceding month, at 1, 3 & 6 months were performed. <h3>Results</h3> 549 patients received heart transplantation during this study period. 407 patients met the inclusion criteria for the primary endpoint investigation. An ALC ≥610 cells/μL was associated with a significantly lower risk of CMV infection (HR 0.57; CI 0.40-0.83; p=0.003). The continuous approach showed similar results with a significantly reduced risk of infection in patients with higher ALC (HR[2-fold increase] 0.78; CI 0.66-0.91; p=0.002). Landmark analyses of mean ALC levels at month 1 & 3, respectively, after transplantation showed a significantly decreased risk of infection in patients with a higher mean ALC (HR[2-fold increase] 0.81; CI 0.65-0.99; p=0.043 & HR 0.46; CI 0.29-0.74; p=0.001). <h3>Conclusion</h3> Absolute lymphocyte count is strongly associated with CMV infection after heart transplantation. ALC value monitoring could serve as an additional tool to predict and minimize the risk of CMV infection.