Background Congenital cytomegalovirus (cCMV) is the most common non-genetic cause of sensorineural hearing loss (SNHL) in children. Ganciclovir has been shown to prevent the continued deterioration in hearing of children with symptomatic cCMV, but some children with cCMV-related SNHL are unidentified in the neonatal treatment period. Neonatal cCMV screening provides an opportunity to identify infants with cCMV-related SNHL who might benefit from early treatment.
Objectives To assess the feasibility (ability to take samples before 3 weeks of age and clinical assessment by 30 days of age) and acceptability (maternal anxiety) of targeted CMV testing of infants who are ‘referred’ for further audiological testing after routine newborn hearing screening programme (NHSP).
Methods Parents of infants who have ‘no clear responses’ on routine NHSP before 22 days of life in London and North East England were approached. Salivary and urine samples were tested by CMV PCR. At recruitment and 3 months, the short form Spielberger State-Trait Anxiety Inventory measured maternal anxiety.
Results 411 infants were recruited. 99% (407/411) returned a sample; 98% (404/411) successfully yielded a CMV result, 6 had cCMV, all diagnosed on salivary samples taken <22 days of age (1.5%; 95% CI 0.6% to 3.2%). Only 50% returned urine samples compared with 99% returning salivary samples (p<0.001). Using saliva swabs 98% were successfully screened for CMV within 3 weeks. All positive screening CMV results were known by day 23, and 5/6 infants with cCMV were assessed within 31 days. Anxiety was not increased in mothers of infants screened for cCMV.
Conclusions Targeted salivary screening for cCMV within the NHSP is feasible, acceptable and detects infants with cCMV-related SNHL who could benefit from early treatment.
- Congenital cytomegalovirus
- sensorineural hearing loss
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What is already known on this topic
Congenital cytomegalovirus (cCMV) is the commonest non-genetic cause of sensorineural hearing loss (SNHL).
In infants with cCMV, antiviral treatment started in the first month of life improves audiological outcome.
The majority of infants with cCMV-related SNHL are ‘asymptomatic’ at birth.
What this study adds
Targeted salivary screening for cCMV within the established newborn hearing screening programme (NHSP) in England is feasible and acceptable to mothers.
Urine samples are not a feasible or preferred way of large-scale screening for cCMV.
cCMV is identified in 0.7% of infants referred from NHSP, and 12.5% of children with newborn identified SNHL in England.
Congenital cytomegalovirus (cCMV) is the commonest congenital infection in the UK. Although case ascertainment is difficult, estimates suggest around 0.3% livebirths are affected.1 ,2 Around 90% of cCMV-infected infants are ‘asymptomatic’ at birth (have no clinically detectable features),3 of whom 6–23% have, or develop, sensorineural hearing loss (SNHL) of which approximately half is detectable at birth.4 cCMV is the most common non-genetic cause of SNHL in children.5 SNHL has a lifelong impact on the individual, significantly impairs quality of life and adversely affects future life outcomes. The estimated burden of cCMV-related SNHL in England is shown as online supplemental data.
To distinguish from postnatally acquired infection, cCMV is diagnosed when CMV is detected from samples taken within the first 21 days of life. Intravenous ganciclovir, if commenced by 1 month of life, appears to improve the audiological6 and neurodevelopmental7 outcomes in cCMV with central nervous system features (microcephaly, intracranial calcifications, abnormal CSF, chorioretinitis or hearing deficits).
In the absence of screening for cCMV, testing in otherwise asymptomatic infants only occurs after hearing loss is confirmed, typically too late to distinguish perinatal from cCMV, or offer treatment within the timescale of the randomised controlled trial.6 The improved hearing outcomes gained from early treatment, the recent availability of valganciclovir (an oral alternative8), emerging evidence about the enhanced audiological benefit of prolonged courses (6 months compared with 6 weeks) of valganciclovir in cCMV (https://idsa.confex.com/idsa/2013/webprogram/Paper43178.html, accessed 5 December 2013) and reliable CMV detection make consideration of screening options imperative.9 ,10 Screening for CMV is possible by using PCR on urine, saliva or dried blood spots (DBS). DBS are routinely collected by 7 days, but have poor sensitivity for detection of CMV. Saliva11 and urine12 are more sensitive alternatives, but protocols for collection are not established.
The newborn hearing screening program (NHSP) aims to detect hearing loss of over 40 dB (moderate or greater) and tests over 98.9% of all newborns in the UK (http://hearing.screening.nhs.uk). However, more than two-thirds of children are >1 month old at their first diagnostic audiological assessment after screening (personal correspondence). Targeted cCMV screening embedded into NHSP (at the initial hearing screen) could identify infants with cCMV-related SNHL13 for whom treatment benefit exists.
The Benefits of Extended Screening Testing (BEST) study aimed to obtain saliva and urine samples for targeted cCMV screening of infants referred for additional audiological testing after NHSP in England, and examine and compare their feasibility (ability to obtain samples before 22 days and clinically assess infants with positive screening before 31 days), and acceptability (determined by maternal anxiety).
Setting and participants
Eligible infants were <22 days old ‘referred’ for further audiological tests after NHSP in North East of England (NE) and South London (SL) between August 2010 and October 2012, with informed consent. Known cCMV cases were excluded. Seven NHS sites (three NE and four SL) participated, all with hospital-based NHSP.
Standard NHSP procedures applied: oto-acoustic emissions testing (OAE), proceeding to automated auditory brainstem response (AABR), if ‘no clear response’ was elicited on OAE. After >48 h in neonatal intensive care units (NICU), both tests are used. The NHSP screeners approached the parents of infants with no clear responses from one or both ears after AABR to gather verbal agreement to be contacted by a researcher involved in a study of ‘a cause of hearing loss’. If verbal consent was given for contact, the research team then approached the parents, preferentially in hospital or by telephone after discharge. Participating parents received information leaflets, consent form, urine collection pack, salivary swab and questionnaires. Receipt of signed consent was considered recruitment. Demographic and clinical data were obtained from medical notes. Samples were obtained by NHS staff or parents. Saliva was collected using a Copan FLOQSwab (sterile neonatal swab in dry tube) placed on the inner surface of the cheek for 1 min, at least 1 h after the last feed. Urine was collected using a pad.14 Samples were sent by post to the Royal Free Hospital for CMV DNA testing using a real-time TaqMan PCR assay as previously described.15 Where CMV was detected on screening, or an infant had SNHL, the DBS was also tested for CMV using PCR and standard diagnostic protocols in use in the Royal Free Hospital.16
Urine and salivary samples were requested from each participant between August 2010 and September 2011. The trial steering committee identified in September 2011 at a planned ad hoc analysis that only 50.6% (89/176) returned urine samples compared with 98.9% (174/176, p<0.001) saliva. Of the completed parental questionnaires at this stage, 97% (76/78) felt the salivary swab was easier to collect than urine and 96% (72/75) indicated their preference for saliva over urine collection. It was therefore deemed that urine collection was not a practical screening method and recommended that saliva swabs only be collected. An ethically approved protocol amendment occurred in December 2011.
Positive results were telephoned to the research team who communicated with parents and local national health service (NHS) Paediatric Infectious Diseases (PID) teams for confirmation and assessment, according to local procedures. Negative results were communicated to the local team weekly by email, and then parents and general practitioners by letter. Infants with cCMV and normal hearing were offered audiological follow-up.
SNHL was suspected when bone conduction ABR thresholds were >30 dBeHL at 4 kHz, and further testing was carried out according to NHSP guidelines.17 If SNHL was confirmed, severity of hearing loss was graded as per the British Society of Audiology recommendations.18 Results of audiological assessments were extracted from the NHSP database (with permissions).
Maternal state anxiety was assessed at recruitment and 3 months by short form Spielberger State-Trait Anxiety Inventory (STAI). Scores range from 20 to 80, ‘normal’ being <36 and clinical anxiety >49.19 Existing STAI data (mothers of infants with unilateral (one-sided) hearing referrals and no CMV screening) were used as ‘control’ anxiety data.20 Maternal views on ‘targeted’ newborn screening for cCMV were also sought.
Wilcoxon signed rank and Mann–Whitney tests were used to compare the STAI scores within groups and were compared with published data using one-sample t test as only mean scores were available. Categorical data were compared using the χ2 test or Fisher exact where appropriate. A p value of <0.05 was considered significant. We determined that with 330 completed STAI scores and an 80% power we would be able to detect a change in STAI of 2.6, although there are no good data to suggest the clinical implications of small differences of STAI score; scores above 49 indicate clinical anxiety.
From 46 242 completed NHSP screens, there were 1133 (2.5%) ‘referrals’ for further audiological testing. In total, 708 families agreed to be approached by study teams and 411 (58%) were recruited (figure 1). Two-thirds were first approached face-to-face (258/411; 64%); such recruitment was more successful than if first contact was by telephone (221/258; 86% compared with 190/450; 42% p<0.001). Methods of approach, recruitment, demographics and details of hearing referral are shown in table 1. More study participants were recorded as White-British than the proportion of NHSP ‘referrals’ from NE/SL recorded as White-British in 2011 (82% vs 58%; p<0.001).
A total of 99% (407/411) of participants returned any sample for CMV testing; 98% (404/411) successfully gave a CMV result. Of 105 urine and 407 saliva samples collected, 21 (4%) did not generate a CMV result: 17/105 (16%) urine samples leaked, 2/407 (0.5%) salivary swabs were received unlabelled and in 2/407 (0.5%) salivary swabs DNA extraction failed. The date of sampling was known in 98.2% (503/512) cases with median age of 4 days (range 0–30 days); 4/512 (0.8%) samples were taken after 21 days. Using saliva 97.6% (401/411) were successfully screened for CMV within 21 days. For the 398 infants with a negative CMV PCR result, the median day of life that parents were informed was day 16 (IQR 11–23), only 6.0% (24) were after 30 days of age. Also, 94.8% (274/289) parents said they found saliva collection fairly or very easy compared with only 41.3% (52/126) for urine collection (p<0.001).
Six children with cCMV were identified (6/404, 1.5%: 95% CI 0.2% to 2.1%), all with CMV PCR positive saliva samples taken <22 days of age. Three of these had cCMV-related SNHL; all three were treated with valganciclovir for 6 weeks (table 2). No difference in the rate of cCMV was identified between NE and SL (NE 5/295, 1.7%; 95% CI 0.6% to 3.9% and SL 1/110, 0.9%; 95% CI 0% to 5.0% p=0.686). Summary screening and diagnostic results for the six positive cases are given in table 2.
Positive results were available on day 4–23 of age (median 9 days) and the first appointment with PID specialists was on day 8–43 of age (median 12 days). Formal ABRs on these infants were available on day 4–28 of age (median 14 days). A decision regarding treatment occurred between day 20 and 43 of life (median 25 days). Only one participant was seen by a PID specialist after 30 days of age; this was a telephone recruit ‘referred’ from NHSP on day 2, with saliva taken on day 14 and the result known on day 23. Specialist follow-up was not possible until day 43 of life, by which time hearing was known to be normal and treatment was not offered.
STAI scores were available on 84% (347/411) participants at recruitment and 52% (212/411) at 3 months. Compared with controls, there was no significant difference in anxiety at recruitment (table 3). At 3 months, STAI was lower than at recruitment (mean difference −3.2, 95% CI difference −5.3 to −1.0, p=0.004) and lower than controls (table 3). No significant relationship was identified between anxiety and infant age or days since NHSP and STAI. Statistically significant differences in STAI existed between regions, ethnicity and type of hearing referral (unilateral, one ear or bilateral, both ears), but these differences were small and no groups reached clinically significant anxiety levels (table 4); these differences between groups did not remain at follow-up. Neither CMV result nor hearing outcome result influenced STAI at follow-up (p>0.05). In total, 89% (193/216) of mothers said they were glad their baby had been screened for cCMV and 97% (217/223) thought that extended screening tests (for cCMV) in babies who are referred after NHSP was a ‘good idea’.
Hearing outcome was known in 96% (393/411) of participants; 348 were satisfactory, 18 had conductive loss, 3 had auditory neuropathy spectrum disorder (all CMV PCR-negative on saliva and DBS) and 24 had SNHL. SNHL was bilateral in 71% (17/24) cases and severe-profound in 38% (9/24). Of the 21 infants with SNHL who were saliva CMV PCR-negative, all were also CMV PCR-negative on DBS. cCMV was thus identified in 3/24 (12.5%) of the children with neonatal SNHL identified through NHSP. cCMV-related SNHL was identified in 3/411, 0.7% (95% CI 0.2% to 2.1%) of referrals from NHSP.
This is the first published study to examine the feasibility and acceptability of a cCMV screening programme integrated into a NHSP. We have shown that a targeted cCMV screening programme nested within a NHSP is feasible and acceptable to mothers. Samples can be taken and processed to allow infants with cCMV to be identified and reviewed within the currently defined treatment window. The optimal sample for testing is saliva. Targeted cCMV screening within NHSP does not appear to increase maternal anxiety and is supported by most mothers. Screening programmes must be cost-effectively determined in part by disease burden. Relevant calculations can be informed by our findings: ∼1.5% (95% CI 0.6% to 3.2%) of NHSP referrals had cCMV, 0.7% (95% CI 0.2% to 2.1%) had cCMV-related newborn SNHL and 12.5% of infants with SNHL had cCMV.
Only 40% of total referrals from NHSP participated in this study. Losses were due to research procedures and 11% of NHSP referrals were ineligible as >21 days at screening. NHSP data suggest ∼20% of referrals annually are >21 days age, mostly the NICU population. cCMV may be more prevalent in this population21 ,22 with additional risk factors for hearing loss,23 but separate consideration of suitable screening in this high-risk population is needed. In addition, as there is considerable regional variation in NHSPs, virology and PID services, the ability to complete this screen and assess positive children might vary in real life (away from a research study setting); this would need to be examined if national roll out were considered.
Thirty per cent of the eligible hearing referrals either declined any contact from the study team or were not contactable by them. An additional 25% agreed to receive a study pack but did not return consent or samples. Neither of these reasons for non-participation are likely to exert an effect where cCMV screening is part of national screening procedures. We noted our participants who were not ‘White-British’ infants was proportionally less than expected; this has been found in other screening24 and research studies,25 suggesting participants in research differ from the general population; however, when a ‘research screen’ becomes ‘routine practice’, uptake becomes almost universal.24 Under-representation of ethnic minorities may mean we have underestimated true UK cCMV rates26 or may have affected anxiety scores.27
We chose to compare maternal anxiety with previously published control data collected from 23 NHSP pilot sites, with timing of STAI at 3–4 weeks postpartum and unilateral referrals.20 Other studies have failed to show a significant change of STAI score between 3 days and 6 weeks postpartum.28 Mothers of bilateral NHSP referrals were found to have higher STAI scores than unilateral referrals in our study and the control study (although only our data reached statistical significance). Therefore, inclusion of both unilateral and bilateral NHSP referrals in our study is likely to have over rather than under-reported anxiety, and we therefore do not consider that we will have missed important clinical maternal anxiety with this comparison.
Although we did not detect additional maternal anxiety and found screening to be supported by most mothers, this differs from a study in the USA where 20% of respondents to a public health questionnaire were ‘opposed’ to universal cCMV screening.29 This difference may be explained by our targeted approach or to the self-selection of study participants who support the idea of additional screening. This is the first study to evaluate this important aspect of screening criteria and suggests that targeted cCMV screening will not cause increased parental anxiety.
Of NHSP referrals, we identified cCMV in 1.5% and cCMV-related newborn SNHL in 0.7% (95% CI 0% to 1.5%). The rate of cCMV-related SNHL is about half that identified in two previous US studies,13 ,30 although the CIs overlap. Considering that the latest data from NHSP suggest that the referral rate from NHSP is 2.3% (15 506/675 861), our approach is expected to identify 113 (31–326) infants with cCMV-related SNHL each year within England. This is consistent with the expected burden of cCMV-related newborn SNHL in otherwise asymptomatic infants in England, derived from available data (see online supplemental data). Although the proportion of infants with SNHL identified to have cCMV is within the proportions attributed to CMV by others,31 other coincidental contributory causes are possible. GJB2 mutations (the most common genetic cause of childhood SNHL) coexist with cCMV in up to 21% neonatal SNHL.32–34 Currently, UK recommendations suggest testing for both,35 ,36 but this is not consistent37 and, if retrospective on DBS, is insufficiently sensitive.38
Since the NE and SL have hospital-based NHSP screening sites, we have only demonstrated feasibility in this setting. Nationally, 20% of screening is community based. The methodology used could be applied to the community setting, but the time target for community NHSP screenings would need reducing from the current 5 weeks.
In conclusion, we have shown targeted salivary cCMV screening within the established UK NHSP and NHS services in England is feasible, acceptable and can identify infants with cCMV-related SNHL who could benefit from early treatment. A health economic analysis of this proposed programme is also important to policymakers, and our group is preparing to address this within a separate publication. Screening uptake remains to be determined, but once integrated within the standard NHSP diagnostic pathway, with salivary swabs being taken by the screeners at the time of ‘referral’, it is likely to be high. With appropriate training we would not expect there to be any important negative impact for the parents or the screeners providing information on cCMV and taking salivary samples, but these issues are currently being examined within ‘BEST2’ (Benefits of Extended Screening Testing 2) study (details available at http://public.ukcrn.org.uk/search/StudyDetail.aspx?StudyID=15119). Raising awareness of cCMV alone may also impact on incidence,39–41 giving a secondary public health benefit from screening.
We would like to thank the families who participated in this study and to the members of CMV Action UK (http://cmvaction.org.uk) who supported the development of this study. We would also like to acknowledge Dr Gillian Colville, St Georges Hospital, for her review of the acceptability data and its interpretation. We would also like to thank the NHSP hearing screeners in the North East and South London for their support and involvement in this study. We are grateful to Dr Mike Vincent, Dr Wendy Albuquerque and Dr Nuria Martinez-Alier as principal investigators of study sites, as well as The Newcastle Hospitals NHS Trust, Northumbria NHS Trust, St Georges Healthcare NHS Trust, Kingston Hospital NHS Trust, Epsom and St Helier Hospitals NHS Trust and Guys and St Thomas’ NHS Trust. We would also like to thank Lynda Shah and paediatric CLRN nursing staff at Newcastle Hospitals and Northumbria NHS Trusts and the neonatal medical staff at Newcastle Hospitals for support in recruiting, and to the diagnostic virology team at the Royal Free Hospital Virology Department for performing the PCR tests.
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Files in this Data Supplement:
- Data supplement 1 - Online supplement
Contributors The idea for this study was conceived by JEC and MS. The protocol was drafted by SW and EJW, and all authors contributed to its final design. Patients were recruited by EJW, SK, NDE and JEB. CA was the lead for the diagnostic services at the Royal Free Hospital. EJW and PJ analysed the data. EJW, JEC and JEB wrote the first draft manuscript, and all authors have revised subsequent drafts and approved the final version.
Funding This study was funded by Sparks, the children's medical research charity (http://www.sparks.org.uk). COPAN donated 200 swabs at the start of this study but played no role in the conception, design or analysis of the study. Sparks grant reference 09NGH01.
Competing interests None.
Ethics approval The Sunderland Research Ethics Committee approved the study (10/H0904/25 in June 2010).
Provenance and peer review Not commissioned; externally peer reviewed.