Adulteration of urine drug testing: Case report and review

Abstract

To study the value of slow vertex response (SVR) in the evaluation of hearing loss by comparing the hearing thresholds acquired with SVR and pure tone audiometry (PTA). Twenty-five subjects (40 ears) with sensorineural hearing loss were tested by PTA and SVR. According to the thresholds of PTA, these ears were subdivided into mild, moderate and severe hearing loss groups, and rank sum test was performed on the thresholds of SVR and PTA for all the hearing loss groups. Then, the correlation between PTA thresholds and SVR thresholds was analyzed and the mathematical models were established for predicting behavioral thresholds by the thresholds of SVR. At four test frequencies (0.5, 1, 2 and 4kHz), the thresholds of SVR had high correlations with thresholds of PTA. Four liner regression equations were established, and the correlation coefficient(r) were 0.971, 0.976, 0.957 and 0.928, respectively (P < 0.05). Back substitution test showed that the liner regression equations would be an easy method for estimating the behavior thresholds. The behavioral threshold can be well judged and evaluated by the liner regression equations established with SVR thresholds.