The distraction test: The last word?

Abstract

Universal Newborn Hearing Screening (UNHS) programmes have been widely implemented, but their costs, benefits and long-term logistics remain to be clearly defined. There are few rigorous evaluations of alternative strategies. In this paper, we evaluate the performance of the distraction test component of the two-tiered Victorian Infant Hearing Screening Program (VIHSP). All babies born in the State of Victoria, Australia in 1993 who survived the neonatal period were screened for the presence of risk factors for hearing loss. Those at-risk were referred for Auditory Brainstem Evoked Response (ABR) screening by a professional audiologist. All others were screened by modified distraction test at age 7-9 months. This birth cohort was followed through age 6 for diagnoses of congenital hearing loss resulting in fitting of hearing aids. Estimates of false-positives, false-negatives, sensitivity, specificity and positive predictive values were determined for the distraction test as a population screen. Ages at diagnosis and aid fitting for screen failures with hearing loss were compared with current goals. For targeted (moderate or greater-aided) losses, the distraction test yielded eight (0.02%) documented false-negatives (one severe and seven moderate) and an estimated 4265 (99%) false-positives. Distraction test sensitivity was 65%, specificity 91% and PPV 0.3%. Mean age at diagnosis for distraction test failures across all severities, including mild losses, was 23 (SD 18) months with a mean age at aid fitting of 26 (SD 20) months. The distraction test screen generated large numbers of false-positives and a significant number of false-negatives, performing particularly poorly with moderate losses. Ages at diagnosis and aid fitting for screen failures were far older than currently accepted goals. There is little evidence that the distraction test can be made to work acceptably as a population-based screen.