Otoacoustic emissions versus audiometry in monitoring hearing loss after long-term noise exposure - a systematic review

Objectives The objective of this systematic review was to compare otoacoustic emissions (OAE) with audiometry in their effectiveness to monitor effects of long-term noise exposure on hearing. Methods We conducted a systematic search of MEDLINE, Embase and the non-MEDLINE subset of PubMed up to March 2016 to identify longitudinal studies on effects of noise exposure on hearing as determined by both audiometry and OAE. Results This review comprised 13 articles, with 30-350 subjects in the longitudinal analysis. A meta-analysis could not be performed because the studies were very heterogeneous in terms of measurement paradigms, follow-up time, age of included subjects, inclusion of data points, outcome parameters and method of analysis. Overall there seemed to be small changes in both audiometry and OAE over time. Individual shifts were detected by both methods but a congruent pattern could not be observed. Some studies found that initial abnormal or low-level emissions might predict future hearing loss but at the cost of low specificity due to a high number of false positives. Other studies could not find such predictive value. Conclusions The reported heterogeneity in the studies calls for more uniformity in including, reporting and analyzing longitudinal data for audiometry and OAE. For the overall results, both methods showed small changes from baseline towards a deterioration in hearing. OAE could not reliably detect threshold shifts at individual level. With respect to the predictive value of OAE, the evidence was not conclusive and studies were not in agreement. The reported predictors had low specificity.