Reliable methods to screen newborns for congenital cytomegalovirus (CMV) infection are needed for identification of infants at increased risk for hearing loss. Since dried blood spots (DBS) are routinely collected for metabolic screening from all newborns in the United States, there has been interest in using DBS polymerase chain reaction (PCR)-based methods for newborn CMV screening.
To determine the diagnostic accuracy of DBS real-time PCR assays for newborn CMV screening
Design, Setting, and Participants
Between March 2007 and May 2008, infants born at seven medical centers in the U.S. were enrolled in the CMV and Hearing Multicenter Screening (CHIMES) study. Newborn saliva specimens were tested for the detection of early antigen fluorescent foci (DEAFF). Results of saliva DEAFF were compared with a single-primer (from 03/07 to 12/07) and a two-primer (from 01/08 to 05/08) DBS real-time PCR. Infants positive by screening DEAFF or PCR were enrolled in follow-up to confirm congenital infection by the reference standard method, DEAFF on saliva or urine.
Main Outcome Measures
Sensitivity, specificity and positive and negative likelihood ratios (LRs) of single-primer and two-primer DBS real-time PCR assays for identifying infants with confirmed congenital CMV infection.
Congenital CMV infection was confirmed in 92 of 20,448 (0.45%; 95% CI, 0.36–0.55) infants. Ninety-one of 92 infants were saliva DEAFF positive on screening. Of the 11,422 infants screened using the single-primer DBS PCR, 17 of 60 (28%) infants were positive with this assay, whereas, among the 9,026 infants screened using the two-primer DBS PCR, 11 of 32 (34%) infants were positive. The single-primer DBS PCR identified congenital CMV infection with a sensitivity of 28.3% (95% CI, 17.4–41.4%), specificity, 99.9% (95% CI, 99.9–100%), positive LR, 803.7 (95% CI, 278.7–2317.9), and negative LR, 0.7 (95% CI, 0.6–0.8). The positive and negative predictive values of the single-primer DBS PCR were 80.9% (95% CI, 58.1–94.5%) and 99.6% (95% CI, 99.5–99.7%), respectively. The two-primer DBS PCR assay identified infants with congenital CMV infection with a sensitivity of 34.4% (95% CI, 18.6–53.2%), specificity, 99.9% (95% CI, 99.9–100%), positive LR, 3088.9 (95% CI, 410.8–23226.7), and negative LR, 0.7 (95% CI, 0.5–0.8). The positive and negative predictive values of the two-primer DBS PCR were 91.7% (95% CI, 61.5–99.8%) and 99.8% (95% CI, 99.6–99.9%), respectively.
Among newborns, CMV testing with DBS real-time PCR compared with saliva rapid culture had low sensitivity, limiting its value as a screening test.