Background: Low level CMV viremia is common, and may either progress to higher viral loads that require therapy, or may spontaneously resolve. The clinical predictors of progression and spontaneous viral clearance are not well defined.

Methods: We performed a retrospective cohort study of solid organ transplant recipients who had the onset of low-level CMV viremia (between 138 and 999 IU/mL) from January 2010-December 2016. Progression was defined as a rise in viral load ≥ 1000 IU/ml or development of symptoms. Spontaneous clearance was defined as a decline in viral load below the assay threshold without antiviral treatment. Clinical and laboratory parameters were assessed for their predictive value. Patients were followed for 8 weeks from the onset of viremia.

Results: A total of 233 patients were identified as follows: lung (n=104), liver (n=89), kidney (n=23), other (n=17); median age was 60 years (range 24-80). Median CMV viral load at onset was 367 IU/ml at a median of 5 months (range 1-241) post-transplant. Of these, 90/233 (38.6%) patients progressed to a high viral load, 103/233 (44.2%) cleared viremia spontaneously, and 40/223 (17.9%) had persistent low level viremia at the end of follow-up. A subset of patients also developed CMV disease (syndrome or tissue-invasive disease) at low level viremia (18/223; 8.0%). In multivariate analysis, lung transplantation was significantly associated with progression to high viral load (p=0.001; OR 2.89 (95%CI 1.56, 5.35)). However, prior treated CMV infection anytime post-transplant was protective against progression (p<0.001; OR 0.09 (95%CI 0.04, 0.22)). Other factors such as creatinine clearance or immunosuppression were not associated with progression.

Conclusion: Our study finds that previous CMV infection significantly decreased the likelihood of low level viremia progression suggesting that CMV immunity plays a role in progression. On the other hand, lung transplantation was the significant predictor of progression to high viral load. Therefore, the first episode of low-level CMV viremia warrants close follow-up and possibly earlier initiation of treatment, especially in lung transplant recipients.

CITATION INFORMATION: Natori Y., Humar A., Alghamdi A., Kumar D. Evaluation of Risk Factors for Progression of Low Level CMV Viremia in Solid Organ Transplant Recipients Am J Transplant. 2017;17 (suppl 3).

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