A screening program to detect aminoglycoside- induced ototoxicity

To the Editor: We note Ahmed and colleagues’ extensive case series of patients with severe vestibulopathy due to aminoglycosides.1 We attempted to develop a hospital-based screening program to detect vestibulopathy in inpatients that may be informative for others considering similar programs.

We established a pilot project involving student pharmacists. Patients who received more than a single dose of any aminoglycoside antibiotic were identified by therapeutic drug monitoring and by ward pharmacists. We intended that the clinical pharmacist would screen all patients using the dynamic visual acuity test2 soon after they commenced treatment with aminoglycosides and twice a week for each week of treatment. For the purpose of this pilot, we excluded patients who had received previous multiple courses of aminoglycosides as treatment for cystic fibrosis or following lung transplantation, who had all taken part in a previous (unpublished) study.

We identified 82 eligible patients who received aminoglycosides over a 12-week period. Clinical testing was not possible in 47 patients during their treatment course: 16 patients had communication difficulties that precluded testing, 15 were in intensive care, six had an impaired conscious state or were uncooperative, two were unable to move their necks, three had already been discharged, and five patients were deceased. Clinical screening was only performed on 35 patients, three of whom had clinical evidence of possible ototoxicity and were referred for further evaluation. None of the patients was diagnosed with aminoglycoside-induced ototoxicity after formal otovestibular testing.

As Ahmed and colleagues note, vestibular toxicity is often only apparent when patients become ambulatory and is almost certainly under-recognised.1 Our experience, where clinical screening was not possible in most patients, shows some of the difficulties in detecting vestibular toxicity in hospital inpatients. Because of these problems, we reinforce that the risks and benefits of gentamicin need to be carefully considered where clinical assessment is difficult, and that gentamicin is relatively contraindicated in patients with pre-existing balance or mobility problems. For most patients receiving short courses of aminoglycosides, post-discharge telephone contact is probably more feasible for identifying patients with vestibular toxicity who may require rehabilitation.