Congenital Cytomegalovirus Severity Definitions and Treatment Decisions around the World: A Systematic Scoping Review of the Literature

Congenital cytomegalovirus (cCMV) is the most common cause of congenital infection and the leading cause of non-genetic sensorineural hearing loss in childhood. While treatment trials have been conducted in symptomatic children, defining asymptomatic infection can be complex. We performed a scoping review to understand how infection severity is defined and treated globally, as well as the various indications for initiating treatment. We conducted an electronic search of MEDLINE, EMBASE, Scopus, and the Cochrane Library, using combinations of the following terms: "newborn", "baby", "child", "ganciclovir", "valganciclovir", and "cytomegalovirus" or "CMV". We included eligible prospective and retrospective studies, case series, and randomized clinical trials (RCTs) published up to May 2024. A total of 26 studies were included, of which only 5 were RCTs. There was significant heterogeneity between studies. The most commonly considered criteria for symptomatic infection were microcephaly (23/24 studies), abnormal neuroimaging (22/24 studies), chorioretinitis/ocular impairment (21/24 studies), and hearing impairment (20/24 studies). Two studies also included asymptomatic newborns in their treatment protocols. Outcome measures varied widely, focusing either on different hearing assessments or neurocognitive issues. Our literature analysis revealed significant variability and heterogeneity in the definition of symptomatic cCMV infection and, consequently, in treatment approaches. A consensus on core outcomes and well-conducted RCTs are needed to establish treatment protocols for specific groups of newborns with varying manifestations of cCMV.