Training VHWs to screen hearing using DPOAE and assist in tele-diagnostic ABR testing
The personnel who conduct hearing screenings are vital for successful implementation of these programs. Hearing screening programs have routinely trained nurses to conduct OAE and/or ABR screening in hospital-based programs in Western countries. In India, it is often the audiologist who conducts the screening [9, 11, 12, 20]. Under the NPPCD program, grassroots level workers are trained to provide hearing screenings using a high risk checklist and behavioural observation [14]. The limitations of screening hearings using checklists and subjective measures are well documented [17, 21], whereas objective screenings using OAE/AABR are known to have higher sensitivity and specificity [22,23,24].
In this program, VHWs conducted objective hearing screenings after receiving systematic training and repeated evaluations. Some programs have trained grassroots workers [25, 26] but little is described about the content or manner of training [27, 28]. In this program, VHWs underwent a five-day training program where material was taught on ear anatomy, hearing phsysiology, early identification and hearing loss interventions. Training included demonstrations and hands-on training in DPOAE screening and ABR assistance. Knowledge and skill retention was assessed periodically post-training. Regular training and supervision is recommended to improve health workers’ ability to successfully screen [29], as such regular review of manual, videos and troubleshooting procedures were encouraged. Monthly meetings were used as additional opportunities to review screening protocols, information to be disseminated in the community, documentation, and equipment maintenance. Such refresher training was useful in retention of information and skill, and reflected in the performance of VHWs in the periodic evaluations conducted.
Outcomes of community-based hearing screening
Hospital-based hearing screening programs for infants are evaluated using the benchmarks given by the Joint Committee on Infant Hearing (JCIH). In developing countries, due to lack of infrastructure and manpower, progress has been made towards community-based hearing screening programs for early identification and intervention as an alternative to ignoring the considerable need for hearing health service delivery across India. Since the perspectives and processes of a community-based approach are unique to each community, it is preferable to formulate guidelines specific to such programs. However, in the absence of appropriate guidelines, JCIH, 2007 was used as a reference to discuss the findings of this program [30].
Hansen et al. (2008) suggests that community health worker-based programs increase the coverage and equity of health service delivery. In this community-based program, the coverage rate (77%) was found to be less than the recommended coverage for hospital-based programs (95%). Information on new births must be accurate for better coverage, and this is possible with information from the Government Primary Health Centers. However, such a collaboration could not be achieved. Since new birth information was obtained from the community’s pre-school teachers, it is possible that some infants were missed. VHWs also had challenges in accessing some localities in the community due to geographical barriers resulting in poor commuting options.
Hospital-based programs have the opportunity to screen a child’s hearing before the child is discharged, which is not relevant to door-to-door screening in the community. However, coverage achieved in this program demonstrates the success in screening infants and young children who would otherwise not have received screening services.
In another community-based hearing screening model, the coverage rate achieved by nurses in a community clinic-based screening in South Africa was 32.4%. Multiple responsibilities shouldered by nurses along with hearing screening was reported to be one of the major reasons for poor coverage [25, 31]. As a result, the researchers recommended appointing dedicated screening personnel as opposed to sharing existing manpower [25]. In this program, dedicated personnel were recruited to conduct screening; this could explain the higher rate of coverage.
The average time required for screening was eighteen minutes. Testing time included settling time as well as time required to complete documentation. Since screening was conducted in the homes of patients, the environment had to be prepared in addition to readying the child for screening. Therefore, it is reasonable to expect the time taken for screening to be more than that of a hospital-based screening. Notably, time taken for screening by VHWs in this program is similar to that reported in studies conducted by health home visits in communities in the UK, where 20 min [32] and 12.2 min were reported [26].
Follow-up rate for 2nd screening
Hearing screening programs have ensured higher participation in initial screenings but a major challenge remains in ensuring subsequent follow-up [33,34,35,36]. The follow-up rate for 2nd screening in this program is better than those reported in hospital-based hearing screening programs in India [12]. Even in community-based hearing screening programs, the loss to follow-up for 2nd screening was reported to be 52% despite free transportation and no fees [37]. One community clinic-based program in South Africa reports a follow-up rate of 85%, ranging between 50 and 100% across eight community clinics [31]. The results of this study are similar. Better follow-up for 2nd screening in this community-based program can be attributed to the door-to-door screening protocol, where the onus was on the VHW to complete 2nd screenings. It can be surmised from the above studies that when the onus of follow-up is on the parents, follow-up is poorer.
Refer rate
It is noteworthy that, in this community-based screening program, the 2nd screening refer rates were very low, except in four to five-year-old age group. The refer rate was lower than the reported refer rate (3 to 19.4%) in other community-based programs from the African region [31, 37]. In these programs, two-step screenings using TEOAE/AABR and DPOAE/DPOAE were conducted in immunization clinics with higher noise levels.
In this program, refer rates increased with age. High refer rates of 6.3% were noted only among four to five-year-old children. Acquired permanent conductive hearing loss was ruled out as children identified with hearing loss in this age group had asymmetrical sensorineural hearing loss. Therefore, the higher refer rate can be attributed to older children’s resistance to being tested and transient middle ear conditions that are more common in this age group. A similar trend was reported with TEOAE screening conducted by auxiliary nurses in a community-based program in Nigeria [37].
VHWs were trained to recognize the “noisy” message that appears in the screener when the environment is not conducive to adequate screening and knew to pause screening. In addition, having dedicated personnel for screenings provided sufficient time to make multiple attempts during 2nd screenings to ensure that the “refer” was not due to ambient noise.
As per JCIH 2007, the “refer” percentage of all infants who fail an initial screening and fail any subsequent rescreening before a comprehensive audiological evaluation should be less than 4%.This suggests that the community-based screening program was successful in meeting the standards set by JCIH (2007) for hospital-based programs. The validity of the screening conducted by VHWs was previously evaluated and the negative and positive predictive values were 98.8 and 27.2% respectively [38]. These findings supplement the success of the program.
Follow-up for in-person versus tele-ABR diagnostic testing
The advantage, if any, of a tele- ABR diagnostic testing was studied by comparing it to the traditional in-person ABR follow-up rates. As per JCIH standards for hospital-based programs, 90% of infants requiring diagnostic evaluation should be assessed. The rate of follow-up for tele-ABR nearly achieved this benchmark.
All over the world, achieving 100% follow-up for diagnostics is a challenge. Some hospital-based programs in the US, France, and Malaysia showed higher follow-up rates, between 81 to 91% [39, 40]. Other programs in the US reported follow-up rates as low as 11% [35]. In one hearing screening program in the US conducted on four-year-old children, the follow-up rate was only 10% [41]. All hospital-based programs in India have reported 12 and 21% follow-up for 2nd screening and diagnostic assessment respectively [9, 12]. Though there are very few rural community-based studies, it is noteworthy that community clinic-based studies have shown high (91%) follow-up rates [31, 42], due to shorter travel.
The follow-up rate obtained in this program, irrespective of in-person or tele-ABR follow-up, is better than previous reports of follow-up rates in India, and is comparable to the high follow-up rates obtained in community clinic-based programs around the world. This suggests that in general, community-based programs have had greater success with follow-up. In this program, the improved follow-up compliance maybe attributed to the VHWs efforts in mobilizing and monitoring follow-up and therefore strongly supports a community-based model of hearing screening. Improved follow-up for tele-ABR in this program is comparable to the community clinic-based tele-diagnostic testing conducted in the Californian tele-audiology program [43].
The median number of days taken between 2nd screening and tele-ABR follow-ups were 30 days (10–189 days), and for in-person ABR follow-ups were 31 (30–36 days). The range for tele-ABR follow-up was wider. Tele-ABR was conducted once a month in the community, therefore, it was possible to achieve follow-ups as early as 10 days from the time of 2nd screening. Only one child was brought for tele-ABR after 6 months of 2nd screening, when the mother returned from her maternal home. Despite the minimal difference in the median time between the two follow-up methods, it was possible to achieve much earlier follow-ups for tele-ABR. In a mobile ear-screening service, the time between screening and tele-ENT evaluation consistently diminished over three years of the program. This suggests that with time, the tele- follow-up may show significant time gain [44].
According to Thompson et al., 2001, in the US, quality studies demonstrate that if 2041–2794 low-risk and 86–208 high-risk newborns were screened, then one case of moderate-to-profound permanent hearing loss was found. Though this program included children up to five years of age, four out of the 2815 screened were identified with moderate to profound hearing loss between three to five years of age and were recommended to partake in a hearing aid trial. Even though return rate for diagnostics were good, only two parents followed up for hearing aid trials and fitting. Poor follow-up for intervention can be attributed to a lack of awareness about the consequences of hearing loss, financial constraints in undertaking travel to the hospital to access rehabilitation services, and potential wage loss. Spivak et al., 2009, reported similar non-compliance rates for hearing aid fittings, particularly in infants with unilateral hearing loss.
