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

Purpose 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. Methods 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. Results 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). Conclusion 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. 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. 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. 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). 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.