Background: CMV infection is a common complication in allogeneic hematopoietic stem cell transplantation (HSCT). We investigated the association of clinically significant CMV (CS-CMV) infection with clinical outcomes and healthcare resource utilization in allogeneic HSCT patients in Finland.

Methods: This retrospective study included adult patients who received their first allogeneic HSCT between January 1, 2013, and December 31, 2018, at the Turku University Hospital. Data were collected from the hospital data lake. Clinical and healthcare outcomes were investigated at one year and mortality up to three years.

Results: The study included 251 patients. CMV seroprevalence was 69.7%. CS-CMV infection occurred in 59.0% of the patients, and of those, 14.2% had >= 2 infections. The median time to CS-CMV infection was 34.5 days (Q(1)-Q(3) 27.0-45.0). Recipient and donor seropositivity, and lymphoproliferative diseases were associated with higher, and HLA identical sibling donors with lower CS-CMV infection risk. CS-CMV infection was not associated with mortality in three years of follow-up. One hundred thirty-three (89.8%) and 75 (72.8%) patients with and without CS-CMV infection, respectively, were readmitted to the hospital. Patients with CS-CMV infection had more hospital readmissions (incidence rate ratio [IRR] 1.38, 95% confidence interval [CI] 1.10-1.73, p = .005) and patients with one CS-CMV infection (IRR 1.48, 95% CI 1.12-1.94, p = .005) or >= 2 infections had longer length of hospital stay (IRR 2.71, 95% CI 1.76-4.35, p < .001).

Conclusion: CMV seroprevalence is relatively high among Finnish allogeneic HSCT patients. CS-CMV infection was common and associated with a higher readmission rate and longer length of hospital stay.