Nephrotoxicity and
ototoxicity have historically been documented as relatively rare complications of
vancomycin monotherapy. Recent reports have linked aggressive
vancomycin dosing strategies to significant risks of nephrotoxicity. We evaluated the rate of
high-frequency hearing loss detected by audiometry for patients on
vancomycin therapy. For this purpose, we used retrospective case-control analysis of audiometry results for patients on
vancomycin therapy for whom baseline and follow-up exams were available. Analysis of 89 patients for whom audiograms were performed after an average of 27 days of
vancomycin therapy showed a 12% rate of
high-frequency hearing loss, with a trend in univariate analysis toward a higher rate with advanced age. The mean of the highest
vancomycin trough levels for both patients with worsening audiograms and those without worsening audiograms was 19 mg/liter. Regression tree modeling demonstrated that for patients <53 years old, the rate of
high-frequency hearing loss detected by audiogram was 0%, while for patients >53 years old, the incidence was 19% (P = 0.008). We conclude that a significant rate of
high-frequency hearing loss in older patients receiving
vancomycin monotherapy was detected by audiometry. While these data urge caution against continued indiscriminate
vancomycin dose escalation to treat
infections caused by Staphylococcus aureus strains for which
vancomycin MICs are 2 mg/liter, further prospective studies are needed to determine the clinical significance and reversibility of these effects.