Management of chronic suppurative otitis media

In reply: Dugdale correctly refers to the natural history of chronic suppurative otitis media (CSOM), and the spectrum of endpoints. The primary endpoint chosen in our trial after ototopical treatment was a dry ear1 (commonly referred to as a “clinical cure” by other trials2), an outcome to be expected after short-term follow-up. Surgical closure of the tympanic membrane (TM) has also been defined as “curing” CSOM. Attaining a dry ear is essential to TM healing, and is therefore a functionally important outcome.

Brewster seems to confuse intention-to-treat (ITT) analysis with sensitivity analysis. Patients for whom there is no data after random allocation to study groups fall into the “missing” category, and may be included as “failures” in a sensitivity analysis. This may reveal additional information if missing data occurred differentially (ie, in some way associated with the treatments). However, in an ITT analysis, patients (with recorded data) are analysed in the group to which they were randomly allocated, irrespective of the actual treatment they received.3 Our analysis followed this principle and included all children, irrespective of the completeness of their treatment regimen.1 A sensitivity analysis revealed no new information, which was not surprising as the missing data were lost for (ascertained) reasons exclusively unrelated to the treatment, and double-blinding excluded any differential follow-up efforts by the healthcare workers. Consequently, the missing values occurred randomly and our analysis not only follows the ITT principle but is also unbiased (ie, valid with respect to “missing” patients).

We are surprised that our treatment regimen is not feasible in the Northern Territory given that it has been used for years in remote Aboriginal communities in Western Australia. We also confirmed the effectiveness of twice-daily use of ototopical medications, which is simpler than current four-times daily schedules.

In 1996, the World Health Organization recommended that topical aminoglycosides (AG) not be used for CSOM because of ototoxicity.4 Such use is also contraindicated by manufacturers.1 Given the availability of a safer alternative, healthcare professionals face potential medicolegal challenges if they choose ototopical AG to treat CSOM.

The relative superiority of ototopical fluoroquinolones (FQ) over AGs in effecting a dry ear is likely to persist with repeated treatments, as the risk of bacterial resistance generated in CSOM pathogens appears to be very small,5 and is far outweighed by the risks of resistance found with oral or parenteral FQs. In our trial, bacterial resistance to ciprofloxacin in ear isolates was not demonstrated in the short term. Systemic absorption of FQ through ototopical use is also negligible.5 In Japan, ototopical ofloxacin has been used as treatment for CSOM since 1992. Based on repeated nationwide surveys from 1995, increased FQ resistance attributed to ototopical use has not been seen in chronic otitis media isolates (Professor K Suzuki, Department of Otolaryngology, The Second Hospital, Fujita Health University School of Medicine, personal communication).6

Whether antibiotics can affect the interval between purulent episodes of CSOM is predicated on host and environmental factors, as well as the duration of effective drug therapy.

A multifaceted approach to the problem of CSOM, requiring the political will to improve the living conditions of Aboriginal families, access to appropriate primary healthcare, ototopical FQs, and surgery will see a reduction in the rate of this disabling disease.