Comment on: Outcome of a newborn hearing screening program in a tertiary hospital in Malaysia: the first five years. Ann Saudi Med 2011; 31: 24-8.

To the Editor: Despite the fact that the low prevalence of hearing impairment (HI) (0.09%) reported by Ahmad et al1 is apparently pleasing, I presume that the actual prevalence is underestimated. Apart from the high default rate in the Ahmad et al's study1 (33.9% and 40.7% in the second and third screening, respectively), the following considerations must not be overlooked. The techniques used within the newborn hearing screening (NHS) in the Ahmad et al's study,1 notably transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem response (AABR) have limitations in HI detection. The protocols used in the NHS might have various specificities and false positive rates and, hence, alter the prevalence of HI. In a recent Brazilian study,2 the specificity and the false positive rate were assessed in three protocols of NHS: protocol 1, NHS was carried out in 2 steps using TEOAE; protocol 2, NHS was carried out in 2 steps using AABR; and protocol 3, NHS was carried out in 1 step, using the 2 procedures, testing with TEOAE followed by a retest with AABR for all the newborns who did not pass the TEOAE testing. The study showed that the false positive rate and consequently specificity were better for the protocol using AABR, followed respectively by the protocol using TEOAE and using both TEOAE and AABR. Additionally, a semi-automated multiple auditory steady state responses (MSSR) screening system has recently shown promising advantages. The diagnostic sensibility and the positive predictive values of the MSSR semi-automatic screening system were found to be 100% and 96%, respectively, with a specificity of 96% and negative predictive values of 100%.3 Therefore, it could be suggested as a better alternative than TEOAE and AABR for NHS. Additionally, HI might be hereditary and several hundred genes are implicated in its causation. A Malaysian study has shown that 25% of deaf children had a mutation in their GJB2 gene and 62% of these children demonstrated V37I missense mutation.4 It is currently believed that combined audiological and molecular genetic screening might be helpful for the early detection of deafness, including those with only slightly manifest hearing loss at birth.5 Considering the aforementioned remarks it is critical to better highlight the actual prevalence of HI and, consequently, allow institution of suitable early rehabilitation treatment or surgical intervention.