DISCUSSION
NOE presents a challenge both in terms of diagnosis and treatment. It is
an uncommon condition which makes large studies difficult to conduct
and, as such, management options remain poorly defined. Most clinicians
agree that intravenous antibiotics and meticulous glycaemic control are
essential, but the role of surgical intervention, amongst other factors,
remains controversial. Indeed, a survey of over 200 UK otolaryngologists
reveals surprising disparities in management (5).
Evidence from orthopaedic literature concerning osteomyelitis at
subsites other than the external auditory canal has suggested that short
courses of antimicrobial therapy may be suitable for particular patient
groups (4). Short course may offer distinct advantages over long course
antimicrobial therapy; such as fewer drug side effects, lower financial
cost, shorter length of hospital admission, and is more convenient for
patients. There are also advantages to limited surgical debridement,
including de-bulking microbial load, facilitating microbiological
testing, and permit histological analysis for exclusion of malignancy.
Indeed other groups have suggested that deep tissue cultures may be more
useful than superficial swabs (6).
To our knowledge this has not been investigated in NOE until the present
study. In this series allocation to short course +/- surgery vs long
course antimicrobial therapy was determined based on a historical
database of outcomes in NOE treated with a standard long course of
antimicrobial therapy at SRH. We previously identified (unpublished)
positive prognostic factors, and where these are present the patients
were allocated to short course antimicrobial therapy +/- surgery (see
methods). All other patients were allocated to long course antimicrobial
therapy.
Most patients in this series were elderly and most were male. The
majority had extensive comorbidities - as measured by the Charleston
comorbidity index; in particular diabetes mellitus, which was often
poorly controlled; predisposing them to infection. Interestingly,
despite the classical association with NOE, recent data suggests that
diabetes mellitus is not an independent risk factor for 30-day
readmission, prolonged length of stay, or discharge to a rehabilitation
facility (7). Many patients in this series grew bacteria typical for
NOE, such as P. Aeruginosa (8). Few demonstrated no bacterial
growth, which may be a function of having received treatment prior to
microbiological analysis.
Most patients in this series presented with advanced disease, as
measured by otoscopy and CT findings. To be able to compare findings
between patients it is important to have a scoring system to objectively
describe extent of disease. We therefore developed a simple and
intuitive distinct grading system for each, as outlined in methods,
which offer a common language to clinicians that is currently missing in
NOE practice.
Although most patients receiving short course antimicrobial therapy +/-
surgery had positive outcomes, this series is small and not
statistically powered to definitely compare treatment arms. Importantly,
however, we identified that all but one patient in this series survived
and had good outcomes. The patient who did not survive died of related
comorbidities, rather than from complications of NOE. This suggests a
larger trial comparing short course antimicrobial therapy +/- surgery
versus long course antimicrobial therapy for non-inferiority would be
feasible and may well offer distinct advantages for selected patients.