C-reactive protein (CRP) and otorrhoea as prognosticate markers for necrotising otitis externa treatment response: based on a retrospective cohort study of 62 patients.

Background: Recurrence rate of necrotising otitis externa (NOE) after treatment is 15-20%. This is mainly due to a lack of reliable clinical indicator for the resolution of disease.

Aims: We aim to assess the predictability of the otalgia, otorrhoea and C-reactive protein (CRP) levels in a large cohort of sixty-two patients for treatment outcome.

Methods: Consecutive patients treated for NOE in our Nottingham tertiary ENT referral unit were retrospectively reviewed from January 2017 to June 2020. Diagnoses were made based on clinical findings and imaging. Good response to treatment was defined as those who required treatment of not longer than the standard six weeks of systemic antibiotics.

Results: Average age at presentation was 78.4 years. 75.8% of patients were male. 62.9% had diabetes. Ten patients received more than the standard six weeks of systemic antibiotics. Complications from disease progression included cranial nerve neuropathies (14.5%), meningitis (3.2%), and sigmoid sinus thrombosis (3.2%). Two patients had recurrent or persistent NOE and died while on treatment. Delays in normalization of CRP (p = 0.015) and resolution of otorrhoea (p = 0.014) were associated with an increased need for prolonged antibiotic treatment.

Conclusion: Normalisation of CRP and resolution of otorrhea can assist in identifying patients who will likely benefit from a prolonged course of systemic antibiotics.